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NAME

| gm - GraphicsMagick command-line utilities to create, edit, or convert images

Contents

Synopsis
Description
Files and Formats
Options
Environment
Configuration Files
Authors
Copyright

Synopsis

gm animate [ options ... ] file [ [ options ... ] file ... ]

gm composite [ options ... ] change-image base-image [ mask-image ] output-image

gm conjure [ options ] script.msl [ [ options ] script.msl ]

gm convert [ [ options ... ] [ input-file ... ] ... [ output-file ] ]

gm display [ options ... ] file ... [ [options ... ]file ... ]

gm identify file [ file ... ]

gm import [ options ... ] file

gm mogrify [ options ... ] file ...

gm montage [ options ... ] file [ [ options ... ] file ... ] output-file

Description

GraphicsMagick's gm provides a suite of command-line utilities for creating, converting, editing, and displaying images:

Gm display is a machine architecture independent image processing and display facility. It can display an image on any workstation display running an X server.

Gm import reads an image from any visible window on an X server and outputs it as an image file. You can capture a single window, the entire screen, or any rectangular portion of the screen.

Gm montage creates a composite by combining several separate images. The images are tiled on the composite image with the name of the image optionally appearing just below the individual tile.

Gm convert converts an input file using one image format to an output file with the same or differing image format while applying an arbitrary number of image transformations.

Gm mogrify transforms an image or a sequence of images. These transforms include image scaling, image rotation, color reduction, and others. The transmogrified image overwrites the original image.

Gm identify describes the format and characteristics of one or more image files. It will also report if an image is incomplete or corrupt.

Gm composite composites images (blends or merges images together) to create new images.

Gm conjure interprets and executes scripts in the Magick Scripting Language (MSL).

The GraphicsMagick utilities recognize the following image formats:

Name | Mode | Description

  8BIM

*rw-

Photoshop resource format

  AFM

*r--

TrueType font

  APP1

*rw-

Photoshop resource format

  ART

*r--

PF1: 1st Publisher

  AVI

*r--

Audio/Visual Interleaved

  AVS

*rw+

AVS X image

  BIE

*rw-

Joint Bi-level Image experts Group

|  | interchange format

  BMP

*rw+

Microsoft Windows bitmap image

  CAPTION

*r+

Caption (requires separate size info)

  CMYK

*rw-

Raw cyan, magenta, yellow, and black

|  | samples (8 or 16 bits, depending on
|  | the image depth)

  CMYKA

*rw-

Raw cyan, magenta, yellow, black, and

|  | matte samples (8 or 16 bits, depending
|  | on the image depth)

  CUT

*r--

DR Halo

  DCM

*r--

Digital Imaging and Communications in

|  | Medicine image

  DCX

*rw+

ZSoft IBM PC multi-page Paintbrush

  DIB

*rw+

Microsoft Windows bitmap image

  DPS

*r--

Display PostScript

  DPX

*r--

Digital Moving Picture Exchange

  EPDF

*rw-

Encapsulated Portable Document Format

  EPI

*rw-

Adobe Encapsulated PostScript

|  | Interchange format

  EPS

*rw-

Adobe Encapsulated PostScript

  EPS2

*-w-

Adobe Level II Encapsulated PostScript

  EPS3

*-w-

Adobe Level III Encapsulated PostScript

  EPSF

*rw-

Adobe Encapsulated PostScript

  EPSI

*rw-

Adobe Encapsulated PostScript

|  | Interchange format

  EPT

*rw-

Adobe Encapsulated PostScript with TIFF

|  | preview

  FAX

*rw+

Group 3 FAX

  FILE

*r--

Uniform Resource Locator

  FITS

*rw-

Flexible Image Transport System

  FPX

*rw-

FlashPix Format

  FTP

*r--

Uniform Resource Locator

  G3

*rw-

Group 3 FAX

  GIF

*rw+

CompuServe graphics interchange format

  GIF87

*rw-

CompuServe graphics interchange format

|  | (version 87a)

  GRADIENT

*r--

Gradual passing from one shade to

|  | another

  GRANITE

*r--

Granite texture

  GRAY

*rw+

Raw gray samples (8 or 16 bits,

|  | depending on the image depth)

  H

*rw-

Internal format

  HDF

-rw+

Hierarchical Data Format

  HISTOGRAM

*-w-

Histogram of the image

  HTM

*-w-

Hypertext Markup Language and a

|  | client-side image map

  HTML

*-w-

Hypertext Markup Language and a

|  | client-side image map

  HTTP

*r--

Uniform Resource Locator

  ICB

*rw+

Truevision Targa image

  ICM

*rw-

ICC Color Profile

  ICO

*r--

Microsoft icon

  ICON

*r--

Microsoft icon

  IPTC

*rw-

IPTC Newsphoto

  JBG

*rw+

Joint Bi-level Image experts Group

|  | interchange format

  JBIG

*rw+

Joint Bi-level Image experts Group

|  | interchange format

  JP2

*rw-

JPEG-2000 JP2 File Format Syntax

  JPC

*rw-

JPEG-2000 Code Stream Syntax

  JPEG

*rw-

Joint Photographic Experts Group

|  | JFIF format

  JPG

*rw-

Joint Photographic Experts Group

|  | JFIF format

  LABEL

*r--

Text image format

  LOGO

*rw-

GraphicsMagick Logo

  M2V

*rw+

MPEG-2 Video Stream

  MAP

*rw-

Colormap intensities (8 or 16 bits,

|  | depending on the image depth) and
|  | indices (8 or 16 bits, depending
|  | on whether colors exceeds 256).

  MAT

*-w+

MATLAB image format

  MATTE

*-w+

MATTE format

  MIFF

*rw+

Magick image format

  MNG

*rw+

Multiple-image Network Graphics

  MONO

*rw-

Bi-level bitmap in least-significant-

|  | -byte-first order

  MPC

-rw-

Magick Persistent Cache image format

  MPEG

*rw+

MPEG-1 Video Stream

  MPG

*rw+

MPEG-1 Video Stream

  MPR

*r--

Magick Persistent Registry

  MSL

*r--

Magick Scripting Language

  MTV

*rw+

MTV Raytracing image format

  MVG

*rw-

Magick Vector Graphics

  NETSCAPE

*r--

Netscape 216 color cube

  NULL

*r--

Constant image of uniform color

  OTB

*rw-

On-the-air bitmap

  P7

*rw+

Xv thumbnail format

  PAL

*rw-

16bit/pixel interleaved YUV

  PALM

*rw-

Palm Pixmap format

  PBM

*rw+

Portable bitmap format (black and white)

  PCD

*rw-

Photo CD

  PCDS

*rw-

Photo CD

  PCL

*-w-

Page Control Language

  PCT

*rw-

Apple Macintosh QuickDraw/PICT

  PCX

*rw-

ZSoft IBM PC Paintbrush

  PDB

*r--

Pilot Image Format

  PDF

*rw+

Portable Document Format

  PFA

*r--

TrueType font

  PFB

*r--

TrueType font

  PFM

*r--

TrueType font

  PGM

*rw+

Portable graymap format (gray scale)

  PICON

*rw-

Personal Icon

  PICT

*rw-

Apple Macintosh QuickDraw/PICT

  PIX

*r--

Alias/Wavefront RLE image format

  PLASMA

*r--

Plasma fractal image

  PM

*rw-

X Windows system pixmap (color)

  PNG

*rw-

Portable Network Graphics

  PNM

*rw+

Portable anymap

  PPM

*rw+

Portable pixmap format (color)

  PREVIEW

*-w-

Show a preview an image enhancement,

|  | effect, or f/x

  PS

*rw+

Adobe PostScript

  PS2

*-w+

Adobe Level II PostScript

  PS3

*-w+

Adobe Level III PostScript

  PSD

*rw-

Adobe Photoshop bitmap

  PTIF

*rw-

Pyramid encoded TIFF

  PWP

*r--

Seattle Film Works

  RAS

*rw+

SUN Rasterfile

  RGB

*rw+

Raw red, green, and blue samples (8 or

|  | 16 bits, depending on the image depth)

  RGBA

*rw+

Raw red, green, blue, and matte samples

|  | (8 or 16 bits, depending on the image
|  | depth)

  RLA

*r--

Alias/Wavefront image

  RLE

*r--

Utah Run length encoded image

  ROSE

*rw-

70x46 Truecolor test image

  SCT

*r--

Scitex HandShake

  SFW

*r--

Seattle Film Works

  SGI

*rw+

Irix RGB image

  SHTML

*-w-

Hypertext Markup Language and a

|  | client-side image map

  STEGANO

*r--

Steganographic image

  SUN

*rw+

SUN Rasterfile

  SVG

*rw+

Scalable Vector Gaphics

  TEXT

*rw+

Raw text

  TGA

*rw+

Truevision Targa image

  TIF

*rw+

Tagged Image File Format

  TIFF

*rw+

Tagged Image File Format

  TILE

*r--

Tile image with a texture

  TIM

*r--

PSX TIM

  TTF

*r--

TrueType font

  TXT

*rw+

Raw text

  UIL

*-w-

X-Motif UIL table

  UYVY

*rw-

16bit/pixel interleaved YUV

  VDA

*rw+

Truevision Targa image

  VICAR

*rw-

VICAR rasterfile format

  VID

*rw+

Visual Image Directory

  VIFF

*rw+

Khoros Visualization image

  VST

*rw+

Truevision Targa image

  WBMP

*rw-

Wireless Bitmap (level 0) image

  WMF

*r--

Windows Metafile

  WPG

*r--

Word Perfect Graphics

  X

*rw-

X Image

  XBM

*rw-

X Windows system bitmap (black

|  | and white)

  XC

*r--

Constant image uniform color

  XCF

*r--

GIMP image

  XML

*r--

Scalable Vector Gaphics

  XPM

*rw-

X Windows system pixmap (color)

  XV

*rw+

Khoros Visualization image

  XWD

*rw-

X Windows system window dump (color)

  YUV

*rw-

CCIR 601 4:1:1

Modes: |  |
| * | Native blob support
| r | Read
| w | Write
| + | Multi-image

Support for some of these formats require additional programs or libraries. README tells where to find this software.

Note, a format delineated with `+` means that if more than one image is specified, it is composited into a single multi-image file. Use +adjoin if you want a single image produced for each frame.

Your installation might not support all of the formats in the list. To get an up-to-date listing of the formats supported by your particular configuration, run `"convert -list format"`.

Raw images are expected to have one byte per pixel unless gm is compiled in 16-bit mode or in 32-bit mode. Here, the raw data is expected to be stored two or four bytes per pixel, respectively, in most-significant-byte-first order. You can tell if gm was compiled in 16-bit mode by typing "gm version" without any options, and looking for "Q:16" in the first line of output.

Back to Contents

Files and Formats

By default, the image format is determined by its magic number, i.e., the first few bytes of the file. To specify a particular image format, precede the filename with an image format name and a colon (i.e.ps:image) or specify the image type as the filename suffix. The magic number takes precedence over the filename suffix and the prefix takes precedence over the magic number and the suffix in input files. The prefix takes precedence over the filename suffix in output files. To read the "built-in" formats (GRANITE, H, LOGO, NETSCAPE, PLASMA, and ROSE) use a prefix (including the colon) without a filename or suffix. To read the XC format, follow the colon with a color specification. To read the CAPTION format, follow the colon with a text string or with a filename prefixed with the at symbol (@).

When you specify X as your image type, the filename has special meaning. It specifies an X window by id, name, or root. If no filename is specified, the window is selected by clicking the mouse in the desired window.

Specify input_file as - for standard input, output_file as - for standard output. If input_file has the extension .Z or .gz, the file is uncompressed with uncompress or gunzip respectively. If output_file has the extension .Z or .gz, the file is compressed using with compress or gzip respectively.

Finally, when running on platforms that allow it, precede the image file name with | to pipe to or from a system command (this feature is not available on VMS, Win32 and Macintosh platforms). Use a backslash or quotation marks to prevent your shell from interpreting the |.

Use an optional index enclosed in brackets after an input file name to specify a desired subimage of a multi-resolution image format like Photo CD (e.g. `"img0001.pcd[4]"`) or a range for MPEG images (e.g. `"video.mpg[50-75]"`). A subimage specification can be disjoint (e.g. `"image.tiff[2,7,4]"`). For raw images, specify a subimage with a geometry (e.g. `-size 640x512` `"image.rgb[320x256+50+50]"`). Surround the image name with quotation marks to prevent your shell from interpreting the square brackets.

Single images are written with the filename you specify. However, multi-part images (e.g., a multi-page PostScript document with +adjoin specified) are written with the filename followed by a period (.) and the scene number. You can change this behavior by embedding a `%d, %0Nd, %o, %0No, %x,` or `%0Nx` printf format specification in the file name. For example,

        image%02d.miff

writes files image00.miff, image01.miff, etc.

When running a commandline utility, you can prepend an at sign `@` to a filename to read a list of image filenames from that file. This is convenient in the event you have too many image filenames to fit on the command line.

Back to Contents

Options

Options are processed in command line order. Any option you specify on the command line remains in effect for the set of images that follows, until the set is terminated by the appearance of any option or -noop. Some options only affect the decoding of images and others only the encoding. The latter can appear after the final group of input images.

This is a combined list of the commandline options used by the GraphicsMagick utilities (animate, composite, convert, display, identify, import, mogrify and montage).

In this document, angle brackets ("<>") enclose variables and curly brackets ("{}") enclose optional parameters. For example, "-fuzz <distance>{%}" means you can use the option `"-fuzz 10"` or `"-fuzz 2%"`.

| -adjoin

| join images into a single multi-image file

| By default, all images of an image sequence are stored in the same file. However, some formats (e.g. JPEG) do not support more than one image and are saved to separate files. Use +adjoin to force this behavior.

| -affine <matrix>

| drawing transform matrix

| This option provides a transform matrix `{sx,rx,ry,sy,tx,ty}` for use by subsequent -draw or -transform options.

| -antialias

| remove pixel aliasing

| By default antialiasing algorithms are used when drawing objects (e.g. lines) or rendering vector formats (e.g. WMF and Postscript). Use +antialias to disable use of antialiasing algorithms. Reasons to disable antialiasing include avoiding increasing colors in the image, or improving rendering speed.

| -append

| append a set of images

| This option creates a single image where the images in the original set are stacked top-to-bottom. If they are not of the same width, any narrow images will be expanded to fit using the background color. Use +append to stack images left-to-right. The set of images is terminated by the appearance of any option. If the -append option appears after all of the input images, all images are appended.

| -authenticate <string>

| decrypt image with this password

| Use this option to supply a password for decrypting an image or an image sequence, if it is being read from a format such as PDF that supports encryption. Encrypting images being written is not supported.

| -average

| average a set of images

| The set of images is terminated by the appearance of any option. If the -average option appears after all of the input images, all images are averaged.

| -backdrop

| display the image centered on a backdrop.

| This backdrop covers the entire workstation screen and is useful for hiding other X window activity while viewing the image. The color of the backdrop is specified as the foreground color (X11 default is black).

| Refer to X Resources for details.

| -background <color>

| the background color

| The color is specified using the format described under the -fill option.

| -blue-primary <x>,<y>

| blue chromaticity primary point

| -blur <radius>{x<sigma>}

| blur the image with a Gaussian operator

| Blur with the given radius and standard deviation (sigma).

| -border <width>x<height>

| surround the image with a border of color

| See -geometry for details about the geometry specification.

| -bordercolor <color>

| the border color

| The color is specified using the format described under the -fill option.

| -borderwidth <geometry>

| the border width

| -box <color>

| set the color of the annotation bounding box

| The color is specified using the format described under the -fill option.

| See -draw for further details.

| -cache <threshold>

| (This option has been replaced by the -limit option)

| -channel <type>

| the type of channel

| Choose from: Red, Green, Blue, Opacity, Matte, Cyan, Magenta, Yellow, or Black.

| Use this option to extract a particular channel from the image. Matte, for example, is useful for extracting the opacity values from an image.

| -charcoal <factor>

| simulate a charcoal drawing

| -chop <width>x<height>{+-}<x>{+-}<y>{%}

| remove pixels from the interior of an image

| Width and height give the number of columns and rows to remove, and x and y are offsets that give the location of the leftmost column and topmost row to remove.

The x offset normally specifies the leftmost column to remove. If the -gravity option is present with NorthEast, East, or SouthEast gravity, it gives the distance leftward from the right edge of the image to the rightmost column to remove. Similarly, the y offset normally specifies the topmost row to remove, but if the -gravity option is present with SouthWest, South, or SouthEast gravity, it specifies the distance upward from the bottom edge of the image to the bottom row to remove.

| The -chop option removes entire rows and columns, and moves the remaining corner blocks leftward and upward to close the gaps.

| -clip

| apply the clipping path, if one is present

| If a clipping path is present, it will be applied to subsequent operations.

| For example, if you type the following command:

         gm convert -clip -negate cockatoo.tif negated.tif

| only the pixels within the clipping path are negated.

| The -clip feature requires the XML library. If the XML library is not present, the option is ignored.

| -coalesce

| merge a sequence of images

| Each image N in the sequence after Image 0 is replaced with the image created by flattening images 0 through N.

| The set of images is terminated by the appearance of any option. If the -coalesce option appears after all of the input images, all images are coalesced.

| -colorize <value>

| colorize the image with the pen color

| Specify the amount of colorization as a percentage. You can apply separate colorization values to the red, green, and blue channels of the image with a colorization value list delimited with slashes (e.g. 0/0/50).

| -colormap <type>

| define the colormap type

| Choose between shared or private.

This option only applies when the default X server visual is PseudoColor or GRAYScale. Refer to -visual for more details. By default, a shared colormap is allocated. The image shares colors with other X clients. Some image colors could be approximated, therefore your image may look very different than intended. Choose Private and the image colors appear exactly as they are defined. However, other clients may go technicolor when the image colormap is installed.

| -colors <value>

| preferred number of colors in the image

The actual number of colors in the image may be less than your request, but never more. Note, this is a color reduction option. Images with less unique colors than specified with this option will have any duplicate or unused colors removed. The ordering of an existing color palette may be altered. When converting an image from color to grayscale, convert the image to the gray colorspace before reducing the number of colors since doing so is most efficient. Refer to <a href="quantize.html">quantize for more details.

| Note, options -dither, -colorspace, and -treedepth affect the color reduction algorithm.

| -colorspace <value>

| the type of colorspace

| Choices are: CMYK, GRAY, HSL, HWB, OHTA, RGB, Transparent, XYZ, YCbCr, YIQ, YPbPr, or YUV.

| Color reduction, by default, takes place in the RGB color space. Empirical evidence suggests that distances in color spaces such as YUV or YIQ correspond to perceptual color differences more closely than do distances in RGB space. These color spaces may give better results when color reducing an image. Refer to quantize for more details.

| The Transparent color space behaves uniquely in that it preserves the matte channel of the image if it exists.

| The -colors or -monochrome option, or saving to a file format which requires color reduction, is required for this option to take effect.

| -comment <string>

| annotate an image with a comment

Use this option to assign a specific comment to the image, when writing to an image format that supports comments. You can include the image filename, type, width, height, or other image attribute by embedding special format characters listed under the -format option. The comment is not drawn on the image, but is embedded in the image datastream via a "Comment" tag or similar mechanism. If you want the comment to be visible on the image itself, use the -draw option.

| For example,

         -comment "%m:%f %wx%h"

| produces an image comment of MIFF:bird.miff 512x480 for an image titled bird.miff and whose width is 512 and height is 480.

| If the first character of string is @, the image comment is read from a file titled by the remaining characters in the string.

| -compose <operator>

| the type of image composition

The description of composition uses abstract terminology in order to allow the the description to be more clear, while avoiding constant values which are specific to a particular build configuration. Each image pixel is represented by red, green, and blue levels (which are equal for a gray pixel). MaxRGB is the maximum integral value which may be stored in the red, green, or blue channels of the image. Each image pixel may also optionally (if the image matte channel is enabled) have an associated level of opacity (ranging from opaque to transparent), which may be used to determine the influence of the pixel color when compositing the pixel with another image pixel. If the image matte channel is disabled, then all pixels in the image are treated as opaque. The color of an opaque pixel is fully visible while the color of a transparent pixel color is entirely absent (pixel color is ignored).

By definition, raster images have a rectangular shape. All image rows are of equal length, and all image columns have the same number of rows. By treating the opacity channel as a visual "mask" the rectangular image may be given a "shape" by treating the opacity channel as a cookie-cutter for the image. Pixels within the shape are opaque, while pixels outside the shape are transparent. Pixels on the boundary of the shape may be between opaque and transparent in order to provide antialiasing (visually smooth edges). The description of the composition operators use this concept of image "shape" in order to make the description of the operators easier to understand. While it is convenient to describe the operators in terms of "shapes" they are by no means limited to mask-style operations since they are based on continuous floating-point mathematics rather than simple boolean operations.

| By default, the Over composite operator is used. The following composite operators are available:

         Over
         In
         Out
         Atop
         Xor
         Plus
         Minus
         Add
         Subtract
         Difference
         Multiply
         Bumpmap
         Copy
         CopyRed
         CopyGreen
         CopyBlue
         CopyOpacity

| The behavior of each operator is described below.

Over
  The result will be the union of the two image shapes, with opaque areas of change-image obscuring base-image in the region of overlap.
In
  The result is simply change-image cut by the shape of base-image. None of the image data of base-image will be in the result.
Out
  The resulting image is change-image with the shape of base-image cut out.
Atop
  The result is the same shape as base-image, with change-image obscuring base-image where the image shapes overlap. Note this differs from over because the portion of change-image outside base-image's shape does not appear in the result.
Xor
  The result is the image data from both change-image and base-image that is outside the overlap region. The overlap region will be blank.
Plus
  The result is just the sum of the image data. Output values are cropped to MaxRGB (no overflow). This operation is independent of the matte channels.
Minus
  The result of change-image - base-image, with underflow cropped to zero. The matte channel is ignored (set to opaque, full coverage).
Add
  The result of change-image + base-image, with overflow wrapping around (mod MaxRGB+1).
Subtract
  The result of change-image - base-image, with underflow wrapping around (mod MaxRGB+1). The add and subtract operators can be used to perform reversible transformations.
Difference
  The result of abs(change-image - base-image). This is useful for comparing two very similar images.
Multiply
  The result of change-image * base-image. This is useful for the creation of drop-shadows.
Bumpmap
  The result base-image shaded by change-image.
Copy
  The resulting image is base-image replaced with change-image. Here the matte information is ignored.
CopyRed
  The resulting image is the red channel in base-image replaced with the red channel in change-image. The other channels are copied untouched.
CopyGreen
  The resulting image is the green channel in base-image replaced with the green channel in change-image. The other channels are copied untouched.
CopyBlue
  The resulting image is the blue channel in base-image replaced with the blue channel in change-image. The other channels are copied untouched.
CopyOpacity
  The resulting image is the opacity channel in base-image replaced with the opacity channel in change-image. The other channels are copied untouched.

| -compress <type>

| the type of image compression

| Choices are: None, BZip, Fax, Group4, JPEG, Lossless, LZW, RLE or Zip.

| Specify +compress to store the binary image in an uncompressed format. The default is the compression type of the specified image file.

| If LZW compression is specified but LZW compression has not been enabled, the image data will be written in an uncompressed LZW format that can be read by LZW decoders. This may result in larger-than-expected GIF files.

| "Lossless" refers to lossless JPEG, which is only available if the JPEG library has been patched to support it. Use of lossless JPEG is generally not recommended.

| Use the -quality option to set the compression level to be used by JPEG, PNG, MIFF, and MPEG encoders. Use the -sampling-factor option to set the sampling factor to be used by JPEG, MPEG, and YUV encoders for downsampling the chroma channels.

| -contrast

| enhance or reduce the image contrast

| This option enhances the intensity differences between the lighter and darker elements of the image. Use -contrast to enhance the image or +contrast to reduce the image contrast.

| For a more pronounced effect you can repeat the option:

        gm convert rose: -contrast -contrast rose_c2.png

| -convolve <kernel>

| convolve image with the specified convolution kernel

| The kernel is specified as a comma-separated list of integers, ordered left-to right, starting with the top row. The order of the kernel is determined by the square root of the number of entries. Presently only square kernels are supported.

| -crop <width>x<height>{+-}<x>{+-}<y>{%}

| preferred size and location of the cropped image

| See -geometry for details about the geometry specification.

| The width and height give the size of the image that remains after cropping, and x and y are offsets that give the location of the top left corner of the cropped image with respect to the original image. To specify the amount to be removed, use -shave instead.

If the x and y offsets are present, a single image is generated, consisting of the pixels from the cropping region. The offsets specify the location of the upper left corner of the cropping region measured downward and rightward with respect to the upper left corner of the image. If the -gravity option is present with NorthEast, East, or SouthEast gravity, it gives the distance leftward from the right edge of the image to the right edge of the cropping region. Similarly, if the -gravity option is present with SouthWest, South, or SouthEast gravity, the distance is measured upward between the bottom edges.

| If the x and y offsets are omitted, a set of tiles of the specified geometry, covering the entire input image, is generated. The rightmost tiles and the bottom tiles are smaller if the specified geometry extends beyond the dimensions of the input image.

| -cycle <amount>

| displace image colormap by amount

| Amount defines the number of positions each colormap entry isshifted.

| -debug <events>

| enable debug printout

| The `events` parameter specifies which events are to be logged. It can be either `None`, `All`, or a comma-separated list consisting of one or more of the following domains: `Annotate`, `Blob`, `Cache`, `Coder`, `Configure`, `Deprecate`, `Error`, `Exception`, `Locale`, `Render`,`Resource`, `TemporaryFile`, `Transform`, `Warning`, `X11`, or `User`. For example, to log cache and blob events, use

        gm convert -debug "Cache,Blob" rose: rose.png

| The "User" domain is normally empty, but developers can log "User" events in their private copy of GraphicsMagick.

| Use the -log option to specify the format for debugging output.

| Use +debug to turn off all logging.

| An alternative to using -debug is to use the MAGICK_DEBUG environment variable. The allowed values for the MAGICK_DEBUG environment variable are the same as for the -debug option.

| -deconstruct

| break down an image sequence into constituent parts

| This option compares each image with the next in a sequence and returns the maximum bounding region of any pixel differences it discovers. This method can undo a coalesced sequence returned by the -coalesce option, and is useful for removing redundant information from a GIF or MNG animation.

| The sequence of images is terminated by the appearance of any option. If the -deconstruct option appears after all of the input images, all images are deconstructed.

| -define <key>{=<value>},...

| add coder/decoder specific options

This option creates one or more definitions for coders and decoders to use while reading and writing image data. Definitions may be passed to coders and decoders to control options that are specific to certain image formats. If value is missing for a definition, an empty-valued definition of a flag will be created with that name. This is used to control on/off options. Use `+define <key>,...` to remove definitions previously created. Use `+define "*"` to remove all existing definitions.

| The following definitions may be created:

jp2:rate=<value>
  Specify the compression factor to use while writing JPEG-2000 files. The compression factor is the reciprocal of the compression ratio. The valid range is 0.0 to 1.0, with 1.0 indicating lossless compression. If defined, this value overrides the -quality setting. The default quality setting of 75 results in a rate value of 0.06641.
jpeg:preserve-settings
  If the jpeg:preserve-settings flag is defined, the JPEG encoder will use the same "quality" and "sampling-factor" settings that were found in the input file, if the input was in JPEG format. These settings are also preserved if the input is a JPEG file and the output is a JNG file. If the colorspace of the output file differs from that of the input file, the quality setting is preserved but the sampling-factors are not.
ps:imagemask
  If the ps:imagemask flag is defined, the PS3 and EPS3 coders will create Postscript files that render bilevel images with the Postscript imagemask operator instead of the image operator.
tiff:bits-per-sample=<value>
  If the tiff:bits-per-sample key is defined to a value less than the GraphicsMagick Quantum depth, the TIFF coder will write TIFF images with the defined bits per sample, overriding any value stored in the image.
tiff:samples-per-pixel=<value>
  If the tiff:samples-per-pixel key is defined to a value, the TIFF coder will write TIFF images with the defined samples per pixel, overriding any value stored in the image.

| For example, to create a postscript file that will render only the black pixels of a bilevel image, use:

        gm convert bilevel.tif -define ps:imagemask eps3:stencil.ps

| -delay <1/100ths of a second>

| display the next image after pausing

| This option is useful for regulating the animation of image sequences Delay/100 seconds must expire before the display of the next image. The default is no delay between each showing of the image sequence. The maximum delay is 65535.

| You can specify a delay range (e.g. -delay 10-500) which sets the minimum and maximum delay.

| -density <width>x<height>

| horizontal and vertical resolution in pixels of the image

This option specifies the image resolution to store while encoding a raster image or the canvas resolution while rendering (reading) vector formats such as Postscript, PDF, WMF, and SVG into a raster image. Image resolution provides the unit of measure to apply when rendering to an output device or raster image. The default unit of measure is in dots per inch (DPI). The -units option may be used to select dots per centimeter instead.

The default resolution is 72 dots per inch, which is equivalent to one point per pixel (Macintosh and Postscript standard). Computer screens are normally 72 or 96 dots per inch while printers typically support 150, 300, 600, or 1200 dots per inch. To determine the resolution of your display, use a ruler to measure the width of your screen in inches, and divide by the number of horizontal pixels (1024 on a 1024x768 display).

| If the file format supports it, this option may be used to update the stored image resolution. Note that Photoshop stores and obtains image resolution from a proprietary embedded profile. If this profile is not stripped from the image, then Photoshop will continue to treat the image using its former resolution, ignoring the image resolution specified in the standard file header.

| The density option is an attribute and does not alter the underlying raster image. It may be used to adjust the rendered size for desktop publishing purposes by adjusting the scale applied to the pixels. To resize the image so that it is the same size at a different resolution, use the -resample option.

| -depth <value>

| depth of the image

| This is the number of bits in a color sample within a pixel. The only acceptable values are 8 or 16. Use this option to specify the depth of raw images whose depth is unknown such as GRAY, RGB, or CMYK, or to change the depth of any image after it has been read.

| -descend

| obtain image by descending window hierarchy

| -despeckle

| reduce the speckles within an image

| -displace <horizontal scale>x<vertical scale>

| shift image pixels as defined by a displacement map

With this option, composite image is used as a displacement map. Black, within the displacement map, is a maximum positive displacement. White is a maximum negative displacement and middle gray is neutral. The displacement is scaled to determine the pixel shift. By default, the displacement applies in both the horizontal and vertical directions. However, if you specify mask, composite image is the horizontal X displacement and mask the vertical Y displacement.

| -display <host:display[.screen]>

| specifies the X server to contact

| This option is used with convert for obtaining image or font from this X server. See X(1).

| -dispose <method>

| GIF disposal method

| The Disposal Method indicates the way in which the graphic is to be treated after being displayed.

| Here are the valid methods:

        Undefined       No disposal specified.
        None            Do not dispose between frames.
        Background      Overwrite the image area with
                        the background color.
        Previous        Overwrite the image area with
                        what was there prior to rendering
                        the image.

| -dissolve <percent>

| dissolve an image into another by the given percent

| The opacity of the composite image is multiplied by the given percent, then it is composited over the main image.

| -dither

| apply Floyd/Steinberg error diffusion to the image

| The basic strategy of dithering is to trade intensity resolution for spatial resolution by averaging the intensities of several neighboring pixels. Images which suffer from severe contouring when reducing colors can be improved with this option.

| The -colors or -monochrome option is required for this option to take effect.

| Use +dither to turn off dithering and to render PostScript without text or graphic aliasing. Disabling dithering often (but not always) leads to decreased processing time.

| -draw <string>

| annotate an image with one or more graphic primitives

| Use this option to annotate an image with one or more graphic primitives. The primitives include shapes, text, transformations, and pixel operations. The shape primitives are

         point           x,y
         line            x0,y0 x1,y1
         rectangle       x0,y0 x1,y1
         roundRectangle  x0,y0 x1,y1 wc,hc
         arc             x0,y0 x1,y1 a0,a1
         ellipse         x0,y0 rx,ry a0,a1
         circle          x0,y0 x1,y1
         polyline        x0,y0  ...  xn,yn
         polygon         x0,y0  ...  xn,yn
         Bezier          x0,y0  ...  xn,yn
         path            path specification
         image           operator x0,y0 w,h filename

| The text primitive is

         text            x0,y0 string

| The text gravity primitive is

         gravity         NorthWest, North, NorthEast, West, Center,
                         East, SouthWest, South, or SouthEast

| The text gravity primitive only affects the placement of text and does not interact with the other primitives. It is equivalent to using the -gravity commandline option, except that it is limited in scope to the -draw option in which it appears.

| The transformation primitives are

         rotate          degrees
         translate       dx,dy
         scale           sx,sy
         skewX           degrees
         skewY           degrees

| The pixel operation primitives are

         color           x0,y0 method
         matte           x0,y0 method

| The shape primitives are drawn in the color specified in the preceding -stroke option. Except for the line and point primitives, they are filled with the color specified in the preceding -fill option. For unfilled shapes, use `-fill none`

.

| Point requires a single coordinate.

| Line requires a start and end coordinate.

| Rectangle expects an upper left and lower right coordinate.

| RoundRectangle has the upper left and lower right coordinates and the width and height of the corners.

| Circle has a center coordinate and a coordinate for the outer edge.

| Use Arc to inscribe an elliptical arc within a rectangle. Arcs require a start and end point as well as the degree of rotation (e.g. 130,30 200,100 45,90).

| Use Ellipse to draw a partial ellipse centered at the given point with the x-axis and y-axis radius and start and end of arc in degrees (e.g. 100,100 100,150 0,360).

| Finally, polyline and polygon require three or more coordinates to define its boundaries. Coordinates are integers separated by an optional comma. For example, to define a circle centered at 100,100 that extends to 150,150 use:

         -draw 'circle 100,100 150,150'

Paths (See Paths) represent an outline of an object which is defined in terms of moveto (set a new current point), lineto (draw a straight line), curveto (draw a curve using a cubic Bezier), arc (elliptical or circular arc) and closepath (close the current shape by drawing a line to the last moveto) elements. Compound paths (i.e., a path with subpaths, each consisting of a single moveto followed by one or more line or curve operations) are possible to allow effects such as "donut holes" in objects.

| Use image to composite an image with another image. Follow the image keyword with the composite operator, image location, image size, and filename:

         -draw 'image Over 100,100 225,225 image.jpg'

| You can use 0,0 for the image size, which means to use the actual dimensions found in the image header. Otherwise, it will be scaled to the given dimensions. See -compose for a description of the composite operators.

| Use text to annotate an image with text. Follow the text coordinates with a string. If the string has embedded spaces, enclose it in single or double quotes. Optionally you can include the image filename, type, width, height, or other image attribute by embedding special format character. See -comment for details.

| For example,

         -draw 'text 100,100 "%m:%f %wx%h"'

| annotates the image with `MIFF:bird.miff 512x480` for an image titled `bird.miff` and whose width is 512 and height is 480.

| If the first character of string is @, the text is read from a file titled by the remaining characters in the string.

| Rotate rotates subsequent shape primitives and text primitives about the origin of the main image. If the -region option precedes the -draw option, the origin for transformations is the upper left corner of the region.

| Translate translates them.

| Scale scales them.

| SkewX and SkewY skew them with respect to the origin of the main image or the region.

The transformations modify the current affine matrix, which is initialized from the initial affine matrix defined by the -affine option. Transformations are cumulative within the -draw option. The initial affine matrix is not affected; that matrix is only changed by the appearance of another -affine option. If another -draw option appears, the current affine matrix is reinitialized from the initial affine matrix.

| Use color to change the color of a pixel to the fill color (see -fill). Follow the pixel coordinate with a method:

         point
         replace
         floodfill
         filltoborder
         reset

| Consider the target pixel as that specified by your coordinate. The point method recolors the target pixel. The replace method recolors any pixel that matches the color of the target pixel. Floodfill recolors any pixel that matches the color of the target pixel and is a neighbor, whereas filltoborder recolors any neighbor pixel that is not the border color. Finally, reset recolors all pixels.

Use matte to the change the pixel matte value to transparent. Follow the pixel coordinate with a method (see the color primitive for a description of methods). The point method changes the matte value of the target pixel. The replace method changes the matte value of any pixel that matches the color of the target pixel. Floodfill changes the matte value of any pixel that matches the color of the target pixel and is a neighbor, whereas filltoborder changes the matte value of any neighbor pixel that is not the border color (-bordercolor). Finally reset changes the matte value of all pixels.

| You can set the primitive color, font, and font bounding box color with -fill, -font, and -box respectively. Options are processed in command line order so be sure to use these options before the -draw option.

| -edge <radius>

| detect edges within an image

| -emboss <radius>

| emboss an image

| -encoding <type>

| specify the text encoding

| Choose from AdobeCustom, AdobeExpert, AdobeStandard, AppleRoman, BIG5, GB2312, Latin 2, None, SJIScode, Symbol, Unicode, Wansung.

| -endian <type>

| specify endianness (MSB or LSB) of output image

| Use +endian to revert to unspecified endianness.

| -enhance

| apply a digital filter to enhance a noisy image

| -equalize

| perform histogram equalization to the image

| -fill <color>

| color to use when filling a graphic primitive

| Colors are represented in GraphicsMagick in the same form used by SVG. Use "gm convert -list color" to list named colors:

        name               (named color)
        #RGB               (hex numbers, 4 bits each)
        #RRGGBB            (8 bits each)
        #RRRGGGBBB         (12 bits each)
        #RRRRGGGGBBBB      (16 bits each)
        #RGBA              (4 bits each)
        #RRGGBBAA          (8 bits each)
        #RRRGGGBBBAAA      (12 bits each)
        #RRRRGGGGBBBBAAAA  (16 bits each)
        rgb(r,g,b)         (r,g,b are decimal numbers)
        rgba(r,g,b,a)      (r,g,b,a are decimal numbers)

| Enclose the color specification in quotation marks to prevent the "#" or the parentheses from being interpreted by your shell.

| For example,

        gm convert -fill blue ...
        gm convert -fill "#ddddff" ...
        gm convert -fill "rgb(65000,65000,65535)" ...

| The shorter forms are scaled up, if necessary by replication. For example, #3af, #33aaff, and #3333aaaaffff are all equivalent.

| See -draw for further details.

| -filter <type>

| use this type of filter when resizing an image

| Use this option to affect the resizing operation of an image (see -geometry). Choose from these filters:

         Point
         Box
         Triangle
         Hermite
         Hanning
         Hamming
         Blackman
         Gaussian
         Quadratic
         Cubic
         Catrom
         Mitchell
         Lanczos
         Bessel
         Sinc

| The default filter is automatically selected to provide the best quality while consuming a reasonable amount of time. The Mitchell filter is used if the image supports a palette, supports a matte channel, or is being enlarged, otherwise the Lanczos filter is used.

| -flatten

| flatten a sequence of images

| The sequence of images is replaced by a single image created by composing each image after the first over the first image.

| The sequence of images is terminated by the appearance of any option. If the -flatten option appears after all of the input images, all images are flattened.

| -flip

| create a "mirror image"

| reflect the scanlines in the vertical direction.

| -flop

| create a "mirror image"

| reflect the scanlines in the horizontal direction.

| -font <name>

| use this font when annotating the image with text

| You can tag a font to specify whether it is a PostScript, TrueType, or OPTION1 font. For example, `Arial.ttf` is a TrueType font, `ps:helvetica` is PostScript, and `x:fixed` is OPTION1.

| -foreground <color>

| define the foreground color

| The color is specified using the format described under the -fill option.

| -format <type>

| the image format type

| When used with the mogrify utility, this option will convert any image to the image format you specify. See GraphicsMagick(1) for a list of image format types supported by GraphicsMagick, or see the output of 'gm -list format'.

| By default the file is written to its original name. However, if the filename extension matches a supported format, the extension is replaced with the image format type specified with -format. For example, if you specify tiff as the format type and the input image filename is image.gif, the output image filename becomes image.tiff.

| -format <string>

| output formatted image characteristics

| When used with the identify utility, use this option to print information about the image in a format of your choosing. You can include the image filename, type, width, height, Exif data, or other image attributes by embedding special format characters:

         %b   file size
         %c   comment
         %d   directory
         %e   filename extension
         %f   filename
         %h   height
         %i   input filename
         %k   number of unique colors
         %l   label
         %m   magick
         %n   number of scenes
         %o   output filename
         %p   page number
         %q   quantum depth
         %s   scene number
         %t   top of filename
         %u   unique temporary filename
         %w   width
         %x   x resolution
         %y   y resolution
         %#   signature
         \n   newline
         \r   carriage return

| For example,

         -format "%m:%f %wx%h"

| displays MIFF:bird.miff 512x480 for an image titled bird.miff and whose width is 512 and height is 480.

| If the first character of string is @, the format is read from a file titled by the remaining characters in the string.

| You can also use the following special formatting syntax to print Exif information contained in the file:

         %[EXIF:<tag>]

| Where "<tag>" can be one of the following:

         *  (print all Exif tags, in keyword=data format)
         !  (print all Exif tags, in tag_number data format)
         #hhhh (print data for Exif tag #hhhh)
         ImageWidth
         ImageLength
         BitsPerSample
         Compression
         PhotometricInterpretation
         FillOrder
         DocumentName
         ImageDescription
         Make
         Model
         StripOffsets
         Orientation
         SamplesPerPixel
         RowsPerStrip
         StripByteCounts
         XResolution
         YResolution
         PlanarConfiguration
         ResolutionUnit
         TransferFunction
         Software
         DateTime
         Artist
         WhitePoint
         PrimaryChromaticities
         TransferRange
         JPEGProc
         JPEGInterchangeFormat
         JPEGInterchangeFormatLength
         YCbCrCoefficients
         YCbCrSubSampling
         YCbCrPositioning
         ReferenceBlackWhite
         CFARepeatPatternDim
         CFAPattern
         BatteryLevel
         Copyright
         ExposureTime
         FNumber
         IPTC/NAA
         ExifOffset
         InterColorProfile
         ExposureProgram
         SpectralSensitivity
         GPSInfo
         ISOSpeedRatings
         OECF
         ExifVersion
         DateTimeOriginal
         DateTimeDigitized
         ComponentsConfiguration
         CompressedBitsPerPixel
         ShutterSpeedValue
         ApertureValue
         BrightnessValue
         ExposureBiasValue
         MaxApertureValue
         SubjectDistance
         MeteringMode
         LightSource
         Flash
         FocalLength
         MakerNote
         UserComment
         SubSecTime
         SubSecTimeOriginal
         SubSecTimeDigitized
         FlashPixVersion
         ColorSpace
         ExifImageWidth
         ExifImageLength
         InteroperabilityOffset
         FlashEnergy
         SpatialFrequencyResponse
         FocalPlaneXResolution
         FocalPlaneYResolution
         FocalPlaneResolutionUnit
         SubjectLocation
         ExposureIndex
         SensingMethod
         FileSource
         SceneType

| Surround the format specification with quotation marks to prevent your shell from misinterpreting any spaces and square brackets.

| -frame <width>x<height>+<outer bevel width>+<inner bevel width>

| surround the image with an ornamental border

| See -geometry for details about the geometry specification. The -frame option is not affected by the -gravity option.

| The color of the border is specified with the -mattecolor command line option.

| -frame

| include the X window frame in the imported image

| -fuzz <distance>{%}

| colors within this distance are considered equal

| A number of algorithms search for a target color. By default the color must be exact. Use this option to match colors that are close to the target color in RGB space. For example, if you want to automatically trim the edges of an image with -trim but the image was scanned and the target background color may differ by a small amount. This option can account for these differences.

| The distance can be in absolute intensity units or, by appending "%", as a percentage of the maximum possible intensity (255, 65535, or 4294967295).

| -gamma <value>

| level of gamma correction

The same color image displayed on two different workstations may look different due to differences in the display monitor. Use gamma correction to adjust for this color difference. Reasonable values extend from 0.8 to 2.3. Gamma less than 1.0 darkens the image and gamma greater than 1.0 lightens it. Large adjustments to image gamma may result in the loss of some image information if the pixel quantum size is only eight bits (quantum range 0 to 255).

| You can apply separate gamma values to the red, green, and blue channels of the image with a gamma value list delimited with slashes (e.g., 1.7/2.3/1.2).

| Use +gamma value to set the image gamma level without actually adjusting the image pixels. This option is useful if the image is of a known gamma but not set as an image attribute (e.g. PNG images).

| -Gaussian <radius>{x<sigma>}

| blur the image with a Gaussian operator

| Use the given radius and standard deviation (sigma).

| -geometry <width>x<height>{+-}<x>{+-}<y>{%}{@} {!}{<}{>}

| preferred size and location of the Image window.

| By default, the window size is the image size and the location is chosen by you when it is mapped.

| By default, the width and height are maximum values. That is, the image is expanded or contracted to fit the width and height value while maintaining the aspect ratio of the image. Append an exclamation point to the geometry to force the image size to exactly the size you specify. For example, if you specify `640x480!` the image width is set to 640 pixels and height to 480.

| If only the width is specified, the width assumes the value and the height is chosen to maintain the aspect ratio of the image. Similarly, if only the height is specified (e.g., `-geometry x256`), the width is chosen to maintain the aspect ratio.

| To specify a percentage width or height instead, append %. The image size is multiplied by the width and height percentages to obtain the final image dimensions. To increase the size of an image, use a value greater than 100 (e.g. 125%). To decrease an image's size, use a percentage less than 100.

| Use `@` to specify the maximum area in pixels of an image.

Use `>` to change the dimensions of the image only if its width or height exceeds the geometry specification. `<` resizes the image only if both of its dimensions are less than the geometry specification. For example, if you specify `'640x480>'` and the image size is 256x256, the image size does not change. However, if the image is 512x512 or 1024x1024, it is resized to 480x480. Enclose the geometry specification in quotation marks to prevent the `<` or `>` from being interpreted by your shell as a file redirection.

| When used with animate and display, offsets are handled in the same manner as in X(1) and the -gravity option is not used. If the x is negative, the offset is measured leftward from the right edge of the screen to the right edge of the image being displayed. Similarly, negative y is measured between the bottom edges. The offsets are not affected by "%"; they are always measured in pixels.

When used as a composite option, -geometry gives the dimensions of the image and its location with respect to the composite image. If the -gravity option is present with NorthEast, East, or SouthEast gravity, the x represents the distance from the right edge of the image to the right edge of the composite image. Similarly, if the -gravity option is present with SouthWest, South, or SouthEast gravity, y is measured between the bottom edges. Accordingly, a positive offset will never point in the direction outside of the image. The offsets are not affected by "%"; they are always measured in pixels. To specify the dimensions of the composite image, use the -resize option.

| When used as a convert, import or mogrify option, -geometry is synonymous with -resize and specifies the size of the output image. The offsets, if present, are ignored.

When used as a montage option, -geometry specifies the image size and border size for each tile; default is 256x256+0+0. Negative offsets (border dimensions) are meaningless. The -gravity option affects the placement of the image within the tile; the default gravity for this purpose is Center. If the "%" sign appears in the geometry specification, the tile size is the specified percentage of the original dimensions of the first tile. To specify the dimensions of the montage, use the -resize option.

| -gravity <type>

| direction primitive gravitates to when annotating the image.

| Choices are: NorthWest, North, NorthEast, West, Center, East, SouthWest, South, SouthEast.

| The direction you choose specifies where to position the text when annotating the image. For example Center gravity forces the text to be centered within the image. By default, the image gravity is NorthWest. See -draw for more details about graphic primitives. Only the text primitive is affected by the -gravity option.

| The -gravity option is also used in concert with the -geometry option and other options that take <geometry> as a parameter, such as the -crop option. See -geometry for details of how the -gravity option interacts with the <x> and <y> parameters of a geometry specification.

| When used as an option to composite, -gravity gives the direction that the image gravitates within the composite.

| When used as an option to montage, -gravity gives the direction that an image gravitates within a tile. The default gravity is Center for this purpose.

| -green-primary <x>,<y>

| green chromaticity primary point

| -help

| print usage instructions

| -iconGeometry <geometry>

| specify the icon geometry

| Offsets, if present in the geometry specification, are handled in the same manner as the -geometry option, using X11 style to handle negative offsets.

| -iconic

| iconic animation

| -immutable

| make image immutable

| -implode <factor>

| implode image pixels about the center

| -intent <type>

| use this type of rendering intent when managing the image color

| Use this option to affect the the color management operation of an image (see -profile). Choose from these intents: Absolute, Perceptual, Relative, Saturation.

| The default intent is undefined.

| -interlace <type>

| the type of interlacing scheme

| Choices are: None, Line, Plane, or Partition. The default is None.

| This option is used to specify the type of interlacing scheme for raw image formats such as RGB or YUV.

| None means do not interlace (RGBRGBRGBRGBRGBRGB...),

| Line uses scanline interlacing (RRR...GGG...BBB...RRR...GGG...BBB...), and

| Plane uses plane interlacing (RRRRRR...GGGGGG...BBBBBB...).

| Partition is like plane except the different planes are saved to individual files (e.g. image.R, image.G, and image.B).

| Use Line or Plane to create an interlaced PNG or GIF or progressive JPEG image.

| -label <name>

| assign a label to an image

Use this option to assign a specific label to the image, when writing to an image format that supports labels, such as TIFF, PNG, MIFF, or PostScript. You can include the the image filename, type, width, height, or other image attribute by embedding special format character. A label is not drawn on the image, but is embedded in the image datastream via a "Label" tag or similar mechanism. If you want the label to be visible on the image itself, use the -draw option. See -comment for details.

| For example,

         -label "%m:%f %wx%h"

| produces an image label of MIFF:bird.miff 512x480 for an image titled bird.miff and whose width is 512 and height is 480.

| If the first character of string is @, the image label is read from a file titled by the remaining characters in the string.

| When converting to PostScript, use this option to specify a header string to print above the image. Specify the label font with -font.

| When creating a montage, by default the label associated with an image is displayed with the corresponding tile in the montage. Use the +label option to suppress this behavior.

| -lat <width>x<height>{+-}<offset>{%}

| perform local adaptive thresholding

| Perform local adaptive thresholding using the specified width, height, and offset. The offset is a distance in sample space from the mean, as an absolute integer ranging from 0 to the maximum sample value or as a percentage.

| -level <black_point>{,<gamma>}{,<white_point>}{%}

| adjust the level of image contrast

Give one, two or three values delimited with commas: black-point, gamma, white-point (e.g. 10,1.0,250 or 2%,0.5,98%). The black and white points range from 0 to MaxRGB or from 0 to 100%; if the white point is omitted it is set to MaxRGB-black_point. If a "%" sign is present anywhere in the string, the black and white points are percentages of MaxRGB. Gamma is an exponent that ranges from 0.1 to 10.; if it is omitted, the default of 1.0 (no gamma correction) is assumed. This interface works similar to Photoshop's "Image->Adjustments->Levels..." "Input Levels" interface.

| -limit <type> <value>

| Disk, File, Map, or Memory resource limit

The value for File is in number of files and the values for the other resources are in Megabytes. By default the limits are 256 files, 1024MB memory, 4096MB map, and unlimited disk, but these are adjusted at startup time on platforms that can provide information about available resources. When the limit is reached, GraphicsMagick will fail in some fashion, or take compensating actions if possible. For example, `-limit memory 32 -limit map 64` limits memory When the pixel cache reaches the memory limit it uses memory mapping. When that limit is reached it goes to disk. If disk has a hard limit, the program will fail.

| Resource limits may also be set using environment variables. The environment variables MAGICK_LIMIT_DISK, MAGICK_LIMIT_FILES, MAGICK_LIMIT_MEMORY, and MAGICK_LIMIT_MAP, may be used to set the limits for disk space, open files, heap memory, and memory map size, respectively.

| You can use the option `-list resource` to find out the limits.

| -linewidth

| the line width for subsequent draw operations

| -list <type>

| the type of list

| Choices are: Color, Delegate, Format, Magic, Module, Resource, or Type. The Module option is only available if GraphicsMagick was built to support loadable modules.

| This option lists information about the GraphicsMagick configuration.

| -log <string>

| Specify format for debug log

| This option specifies the format for the log printed when the -debug option is active.

| You can display the following components by embedding special format characters:

         %d   domain
         %e   event
         %f   function
         %l   line
         %m   module
         %p   process ID
         %r   real CPU time
         %t   wall clock time
         %u   user CPU time
         %%   percent sign
         \n   newline
         \r   carriage return

| For example:

        gm convert -debug coders -log "%u %m:%l %e" in.gif out.png

| The default behavior is to print all of the components.

| -loop <iterations>

| add Netscape loop extension to your GIF animation

| A value other than zero forces the animation to repeat itself up to iterations times.

| -magnify <factor>

| magnify the image

| -map <filename>

| choose a particular set of colors from this image

| [convert or mogrify]

| By default, color reduction chooses an optimal set of colors that best represent the original image. Alternatively, you can choose a particular set of colors from an image file with this option.

| Use +map to reduce all images in the image sequence that follows to a single optimal set of colors that best represent all the images. The sequence of images is terminated by the appearance of any option. If the +map option appears after all of the input images, all images are mapped.

| -map <type>

| display image using this type.

| [animate or display]

| Choose from these Standard Colormap types:

         best
         default
         gray
         red
         green
         blue

| The X server must support the Standard Colormap you choose, otherwise an error occurs. Use list as the type and display searches the list of colormap types in top-to-bottom order until one is located. See xstdcmap(1) for one way of creating Standard Colormaps.

| -mask <filename>

| Specify a clipping mask

| The image read from the file is used as a clipping mask. It must have the same dimensions as the image being masked.

| If the mask image contains an opacity channel, the opacity of each pixel is used to define the mask. Otherwise, the intensity (gray level) of each pixel is used.

| Use +mask to remove the clipping mask.

| It is not necessary to use -clip to activate the mask; -clip is implied by -mask.

| -matte

| store matte channel if the image has one

| If the image does not have a matte channel, create an opaque one.

| Use +matte to ignore the matte channel and to avoid writing a matte channel in the output file.

| -mattecolor <color>

| specify the color to be used with the -frame option

| The color is specified using the format described under the -fill option.

| -median <radius>

| apply a median filter to the image

| -mode <value>

| mode of operation

| -modulate brightness[,saturation[,hue]]

| vary the brightness, saturation, and hue of an image

| Specify the percent change in brightness, color saturation, and hue separated by commas. Default argument values are 100 percent, resulting in no change. For example, to increase the color brightness by 20% and decrease the color saturation by 10% and leave the hue unchanged, use: -modulate 120,90.

| Hue is the percentage of absolute rotation from the current position. For example 50 results in a counter-clockwise rotation of 90 degrees, 150 results in a clockwise rotation of 90 degrees, with 0 and 200 both resulting in a rotation of 180 degrees.

| -monochrome

| transform the image to black and white

| -morph <frames>

| morphs an image sequence

| Both the image pixels and size are linearly interpolated to give the appearance of a meta-morphosis from one image to the next.

| The sequence of images is terminated by the appearance of any option. If the -morph option appears after all of the input images, all images are morphed.

| -mosaic

| create a mosaic from an image or an image sequence

| The -page option can be used to establish the dimensions of the mosaic and to locate the images within the mosaic.

| The sequence of images is terminated by the appearance of any option. If the -mosaic option appears after all of the input images, all images are included in the mosaic.

| -name

| name an image

| -negate

| replace every pixel with its complementary color

| The red, green, and blue intensities of an image are negated. White becomes black, yellow becomes blue, etc. Use +negate to only negate the grayscale pixels of the image.

| -noise <radius|type>

| add or reduce noise in an image

The principal function of noise peak elimination filter is to smooth the objects within an image without losing edge information and without creating undesired structures. The central idea of the algorithm is to replace a pixel with its next neighbor in value within a pixel window, if this pixel has been found to be noise. A pixel is defined as noise if and only if this pixel is a maximum or minimum within the pixel window.

| Use radius to specify the width of the neighborhood.

| Use +noise followed by a noise type to add noise to an image. Choose from these noise types:

         Uniform
         Gaussian
         Multiplicative
         Impulse
         Laplacian
         Poisson

| -noop

| NOOP (no option)

| The -noop option can be used to terminate a group of images and reset all options to their default values, when no other option is desired.

| -normalize

| transform image to span the full range of color values

| This is a contrast enhancement technique.

| -opaque <color>

| change this color to the pen color within the image

| The color is specified using the format described under the -fill option.

| See -fill for more details.

| -operator channel operator rvalue[%]

| apply a mathematical or bitwise operator to an image channel

| Apply a low-level mathematical or bitwise operator to a selected image channel or all image channels. Operations which result in negative results are reset to zero, and operations which overflow the available range are reset to the maximum possible value.

| Select a channel from: Red, Green, Blue, Opacity, Matte, Cyan, Magenta, Yellow, Black, or All.

| Select an operator from Add, And, Divide, LShift, Multiply, Or, RShift, Subtract, Xor.

| Rvalue may be any floating point value in the range of 0 to MaxRGB, where MaxRGB is the largest quantum value supported by the GraphicsMagick build (255, 65535, or 4294967295). If a percent (%) symbol is appended to the argument, then the argument has a range of 0 to 100 percent.

| -ordered-dither <channeltype> <NxN>

| ordered dither the image

| The channel or channels specified in the channeltype argument are reduced to binary, using an ordered dither method. The choices for channeltype are:

        all
        intensity
        opacity
        matte

| When channeltype is "all", the color samples are dithered into a graylevel and then that graylevel is stored in the three color channels. Separately, the opacity channel is dithered into a bilevel opacity value which is stored in the opacity channel.

| When channeltype is "intensity", only the color samples are dithered. When channeltype is "opacity" or "matte", only the opacity channel is dithered.

| The choices for N are 2, 3, or 4. When N is 2, the image is divided into 2x2 pixel tiles. In each tile, 0, 1, 2, 3, or 4 pixels are turned to white depending on their intensity. When N is 3, there are 3x3 tiles and 10 levels of gray can be represented. When N is 4, there are 4x4 tiles and 17 levels of gray.

| -page <width>x<height>{+-}<x>{+-}<y>{%}{!}{<}{>}

| size and location of an image canvas

| Use this option to specify the dimensions of the PostScript page in dots per inch or a TEXT page in pixels. The choices for a PostScript page are:

         11x17         792  1224
         Ledger       1224   792
         Legal         612  1008
         Letter        612   792
         LetterSmall   612   792
         ArchE        2592  3456
         ArchD        1728  2592
         ArchC        1296  1728
         ArchB         864  1296
         ArchA         648   864
         A0           2380  3368
         A1           1684  2380
         A2           1190  1684
         A3            842  1190
         A4            595   842
         A4Small       595   842
         A5            421   595
         A6            297   421
         A7            210   297
         A8            148   210
         A9            105   148
         A10            74   105
         B0           2836  4008
         B1           2004  2836
         B2           1418  2004
         B3           1002  1418
         B4            709  1002
         B5            501   709
         C0           2600  3677
         C1           1837  2600
         C2           1298  1837
         C3            918  1298
         C4            649   918
         C5            459   649
         C6            323   459
         Flsa          612   936
         Flse          612   936
         HalfLetter    396   612

| For convenience you can specify the page size by media (e.g. A4, Ledger, etc.). Otherwise, -page behaves much like -geometry (e.g. `-page letter+43+43>`).

This option is also used to place subimages when writing to a multi-image format that supports offsets, such as GIF89 and MNG. When used for this purpose the offsets are always measured from the top left corner of the canvas and are not affected by the -gravity option. To position a GIF or MNG image, use -page{+-}<x>{+-}<y> (e.g. -page +100+200). When writing to a MNG file, a -page option appearing ahead of the first image in the sequence with nonzero width and height defines the width and height values that are written in the MHDR chunk. Otherwise, the MNG width and height are computed from the bounding box that contains all images in the sequence. When writing a GIF89 file, only the bounding box method is used to determine its dimensions.

For a PostScript page, the image is sized as in -geometry and positioned relative to the lower left hand corner of the page by {+-}<x offset>{+-}<y offset>. Use `-page 612x792>`, for example, to center the image within the page. If the image size exceeds the PostScript page, it is reduced to fit the page. The default gravity for the -page option is NorthWest, i.e., positive x and y offset are measured rightward and downward from the top left corner of the page, unless the -gravity option is present with a value other than NorthWest.

| The default page dimensions for a TEXT image is 612x792.

| This option is used in concert with -density.

| Use +page to remove the page settings for an image.

| -paint <radius>

| simulate an oil painting

| Each pixel is replaced by the most frequent color in a circular neighborhood whose width is specified with radius.

| -pause <seconds>

| pause between animation loops [animate]

| Pause for the specified number of seconds before repeating the animation.

| -pause <seconds>

| pause between snapshots [import]

| Pause for the specified number of seconds before taking the next snapshot.

| -pen <color>

| (This option has been replaced by the -fill option)

| -ping

| efficiently determine image characteristics

| -pointsize <value>

| pointsize of the PostScript, OPTION1, or TrueType font

| -preview <type>

| image preview type

| Use this option to affect the preview operation of an image (e.g. `convert file.png -preview Gamma Preview:gamma.png`). Choose from these previews:

         Rotate
         Shear
         Roll
         Hue
         Saturation
         Brightness
         Gamma
         Spiff
         Dull
         Grayscale
         Quantize
         Despeckle
         ReduceNoise
         Add Noise
         Sharpen
         Blur
         Threshold
         EdgeDetect
         Spread
         Shade
         Raise
         Segment
         Solarize
         Swirl
         Implode
         Wave
         OilPaint
         CharcoalDrawing
         JPEG

| The default preview is JPEG.

| -process <command>

| process a sequence of images using a process module

| The command argument has the form module=arg1,arg2,arg3,...,argN where module is the name of the module to invoke (e.g. "analyze") and arg1,arg2,arg3,...,argN are an arbitrary number of arguments to pass to the process module.

| The sequence of images is terminated by the appearance of any option.

| If the -process option appears after all of the input images, all images are processed.

| -profile <filename>

| add ICM, IPTC, or generic profile to image

| `-profile filename` adds an ICM (ICC color management), IPTC (newswire information), or a generic profile to the image

.

| Use `+profile icm`, `+profile iptc`, or `+profile profile_name` to remove the respective profile. Use `identify -verbose` to find out what profiles are in the image file. Use `+profile "*"` to remove all profiles.

| To extract a profile, the -profile option is not used. Instead, simply write the file to an image format such as APP1, 8BIM, ICM, or IPTC.

| For example, to extract the Exif data (which is stored in JPEG files in the APP1 profile), use

        gm convert cockatoo.jpg exifdata.app1

| +progress

| disable progress monitor and busy cursor

By default, when an image is displayed, a progress monitor bar is shown in the top left corner of an existing image display window, and the current cursor is replaced with an hourglass cursor. Use +progress to disable the progress monitor and busy cursor during display operations. While the progress monitor is disabled for all operations, the busy cursor continues to be enabled for non-display operations such as image processing. This option is useful for non-interactive display operations, or when a "clean" look is desired.

| -quality <value>

| JPEG/MIFF/PNG compression level

| For the JPEG and MPEG image formats, quality is 0 (lowest image quality and highest compression) to 100 (best quality but least effective compression). The default quality is 75. Use the -sampling-factor option to specify the factors for chroma downsampling. To use the same quality value as that found by the JPEG decoder, use the `-define jpeg:preserve-settings` flag.

| For the MIFF image format, quality/10 is the zlib compression level, which is 0 (worst but fastest compression) to 9 (best but slowest). It has no effect on the image appearance, since the compression is always lossless.

| For the JPEG-2000 image format, quality is mapped using a non-linear equation to the compression ratio required by the Jasper library. This non-linear equation is intended to loosely approximate the quality provided by the JPEG v1 format. The default quality value 75 results in a request for 16:1 compression. The quality value 100 results in a request for non-lossy compression.

| For the MNG and PNG image formats, the quality value sets the zlib compression level (quality / 10) and filter-type (quality % 10). Compression levels range from 0 (fastest compression) to 100 (best but slowest). For compression level 0, the Huffman-only strategy is used, which is fastest but not necessarily the worst compression.

| If filter-type is 4 or less, the specified filter-type is used for all scanlines:

         0: none
         1: sub
         2: up
         3: average
         4: Paeth

| If filter-type is 5, adaptive filtering is used when quality is greater than 50 and the image does not have a color map, otherwise no filtering is used.

| If filter-type is 6, adaptive filtering with minimum-sum-of-absolute-values is used.

| Only if the output is MNG, if filter-type is 7, the LOCO color transformation and adaptive filtering with minimum-sum-of-absolute-values are used.

| The default is quality is 75, which means nearly the best compression with adaptive filtering. The quality setting has no effect on the appearance of PNG and MNG images, since the compression is always lossless.

| For further information, see the PNG specification.

When writing a JNG image with transparency, two quality values are required, one for the main image and one for the grayscale image that conveys the opacity channel. These are written as a single integer equal to the main image quality plus 1000 times the opacity quality. For example, if you want to use quality 75 for the main image and quality 90 to compress the opacity data, use `-quality 90075`.

| -raise <width>x<height>

| lighten or darken image edges

| This will create a 3-D effect. See -geometry for details details about the geometry specification. Offsets are not used.

| Use -raise to create a raised effect, otherwise use +raise.

| -random-threshold <channeltype> <LOWxHIGH>

| random threshold the image

| The channel or channels specified in the <channeltype> argument are reduced to binary, using an random-threshold method. The choices for channeltype are:

        all
        intensity
        opacity
        matte

When channeltype is "all", the color samples are thresholded into a graylevel and then that graylevel is stored in the three color channels. Separately, the opacity channel is thresholded into a bilevel opacity value which is stored in the opacity channel. For each pixel, a new random number is used to establish the threshold to be used. The threshold never exceeds the specified maximum (HIGH) and is never less than the specified minimum (LOW).

| When channeltype is "intensity", only the color samples are thresholded. When channeltype is "opacity" or "matte", only the opacity channel is thresholded.

| -red-primary <x>,<y>

| red chromaticity primary point

| -region <width>x<height>{+-}<x>{+-}<y>

| apply options to a portion of the image

| The x and y offsets are treated in the same manner as in -crop

.

| -remote

| perform a X11 remote operation

The -remote command sends a command to a "gm display" or "gm animate" which is already running. The only command recognized at this time is the name of an image file to load. This capability is very useful to load new images without needing to restart GraphicsMagick (e.g. for a slide-show or to use GraphicsMagick as the display engine for a different GUI). Also see the +progress option for a way to disable progress indication for a clean look while loading new images.

| -render

| render vector operations

| Use +render to turn off rendering vector operations. This is useful when saving the result to vector formats such as MVG or SVG.

| -resample <horizontal>x<vertical>

| Resample image to specified horizontal and vertical resolution

Resize the image so that its rendered size remains the same as the original at the specified target resolution. Either the current image resolution units or the previously set with -units are used to interpret the argument. For example, if a 300 DPI image renders at 3 inches by 2 inches on a 300 DPI device, when the image has been resampled to 72 DPI, it will render at 3 inches by 2 inches on a 72 DPI device. Note that only a small number of image formats (e.g. JPEG, PNG, and TIFF) are capable of storing the image resolution. For formats which do not support an image resolution, the original resolution of the image must be specified via -density on the command line prior to specifying the resample resolution.

| Note that Photoshop stores and obtains image resolution from a proprietary embedded profile. If this profile exists in the image, then Photoshop will continue to treat the image using its former resolution, ignoring the image resolution specified in the standard file header.

Some image formats (e.g. PNG) require use of metric or english units so even if the original image used a particular unit system, if it is saved to a different format prior to resampling, then it may be necessary to specify the desired resolution units using -units since the original units may have been lost. In other words, do not assume that the resolution units are restored if the image has been saved to a file.

| -resize <width>x<height>{%}{@}{!}{<}{>}

| resize an image

| This is an alias for the -geometry option and it behaves in the same manner. If the -filter option precedes the -resize option, the specified filter is used.

| There are some exceptions:

| When used as a composite option, -resize conveys the preferred size of the output image, while -geometry conveys the size and placement of the composite image within the main image.

| When used as a montage option, -resize conveys the preferred size of the montage, while -geometry conveys information about the tiles.

| -roll {+-}<x>{+-}<y>

| roll an image vertically or horizontally

| See -geometry for details the geometry specification. The x and y offsets are not affected by the -gravity option.

| A negative x offset rolls the image left-to-right. A negative y offset rolls the image top-to-bottom.

| -rotate <degrees>{<}{>}

| apply Paeth image rotation to the image

Use `>` to rotate the image only if its width exceeds the height. `<` rotates the image only if its width is less than the height. For example, if you specify `-rotate "-90>"` and the image size is 480x640, the image is not rotated. However, if the image is 640x480, it is rotated by -90 degrees. If you use `>` or `<`, enclose it in quotation marks to prevent it from being misinterpreted as a file redirection.

| Empty triangles left over from rotating the image are filled with the color defined as background (class backgroundColor). The color is specified using the format described under the -fill option.

| -sample <geometry>

| scale image using pixel sampling

| See -geometry for details about the geometry specification. -sample ignores the -filter selection if the -filter option is present. Offsets, if present in the geometry string, are ignored, and the -gravity option has no effect.

| -sampling-factor <horizontal_factor>x<vertical_factor>

| sampling factors used by JPEG or MPEG-2 encoder and YUV decoder/encoder.

| This option specifies the sampling factors to be used by the JPEG encoder for chroma downsampling. If this option is omitted, the JPEG library will use its own default values. When reading or writing the YUV format and when writing the M2V (MPEG-2) format, use -sampling-factor 2x1 to specify the 4:2:2 downsampling method.

| To use the same sampling factors as those found by the JPEG decoder, use the `-define jpeg:preserve-settings` flag.

| -scale <geometry>

| scale the image.

| See -geometry for details about the geometry specification. -scale uses a simpler, faster algorithm, and it ignores the -filter selection if the -filter option is present. Offsets, if present in the geometry string, are ignored, and the -gravity option has no effect.

| -scene <value>

| set scene number

| This option sets the scene number of an image or the first image in an image sequence.

| -scenes <value-value>

| range of image scene numbers to read

| Each image in the range is read with the filename followed by a period (.) and the decimal scene number. You can change this behavior by embedding a %d, %0Nd, %o, %0No, %x, or %0Nx printf format specification in the file name. For example,

        gm montage -scenes 5-7 image.miff

| makes a montage of files image.miff.5, image.miff.6, and image.miff.7, and

        gm animate -scenes 0-12 image%02d.miff

| animates files image00.miff, image01.miff, through image12.miff.

| -screen

| specify the screen to capture

| This option indicates that the GetImage request used to obtain the image should be done on the root window, rather than directly on the specified window. In this way, you can obtain pieces of other windows that overlap the specified window, and more importantly, you can capture menus or other popups that are independent windows but appear over the specified window.

| -segment <cluster threshold>x<smoothing threshold>

| segment an image

| Segment an image by analyzing the histograms of the color components and identifying units that are homogeneous with the fuzzy c-means technique.

| Specify cluster threshold as the number of pixels in each cluster must exceed the the cluster threshold to be considered valid. Smoothing threshold eliminates noise in the second derivative of the histogram. As the value is increased, you can expect a smoother second derivative. The default is 1.5. See "Image Segmentation" for details.

| -shade <azimuth>x<elevation>

| shade the image using a distant light source

| Specify azimuth and elevation as the position of the light source. Use +shade to return the shading results as a grayscale image.

| -shadow <radius>{x<sigma>}

| shadow the montage

| -shared-memory

| use shared memory

| This option specifies whether the utility should attempt to use shared memory for pixmaps. GraphicsMagick must be compiled with shared memory support, and the display must support the MIT-SHM extension. Otherwise, this option is ignored. The default is True.

| -sharpen <radius>{x<sigma>}

| sharpen the image

| Use a Gaussian operator of the given radius and standard deviation (sigma).

| -shave <width>x<height>{%}

| shave pixels from the image edges

| Specify the width of the region to be removed from both sides of the image and the height of the regions to be removed from top and bottom.

| -shear <x degrees>x<y degrees>

| shear the image along the X or Y axis

| Use the specified positive or negative shear angle.

Shearing slides one edge of an image along the X or Y axis, creating a parallelogram. An X direction shear slides an edge along the X axis, while a Y direction shear slides an edge along the Y axis. The amount of the shear is controlled by a shear angle. For X direction shears, x degrees is measured relative to the Y axis, and similarly, for Y direction shears y degrees is measured relative to the X axis.

| Empty triangles left over from shearing the image are filled with the color defined as background (class backgroundColor). The color is specified using the format described under the -fill option.

| -silent

| operate silently

| -size <width>x<height>{+offset}

| width and height of the image

| Use this option to specify the width and height of raw images whose dimensions are unknown such as GRAY, RGB, or CMYK. In addition to width and height, use -size with an offset to skip any header information in the image or tell the number of colors in a MAP image file, (e.g. -size 640x512+256).

| For Photo CD images, choose from these sizes:

         192x128
         384x256
         768x512
         1536x1024
         3072x2048

| Finally, use this option to choose a particular resolution layer of a JBIG or JPEG image (e.g. -size 1024x768).

| -snaps <value>

| number of screen snapshots

| Use this option to grab more than one image from the X server screen, to create an animation sequence.

| -solarize <factor>

| negate all pixels above the threshold level

| Specify factor as the percent threshold of the intensity (0 - 99.9%).

| This option produces a solarization effect seen when exposing a photographic film to light during the development process.

| -spread <amount>

| displace image pixels by a random amount

| Amount defines the size of the neighborhood around each pixel to choose a candidate pixel to swap.

| -stegano <offset>

| hide watermark within an image

| Use an offset to start the image hiding some number of pixels from the beginning of the image. Note this offset and the image size. You will need this information to recover the steganographic image (e.g. display -size 320x256+35 stegano:image.png).

| -stereo

| composite two images to create a stereo anaglyph

| The left side of the stereo pair is saved as the red channel of the output image. The right side is saved as the green channel. Red-green stereo glasses are required to properly view the stereo image.

| -stroke <color>

| color to use when stroking a graphic primitive

| The color is specified using the format described under the -fill option.

| See -draw for further details.

| -strokewidth <value>

| set the stroke width

| See -draw for further details.

| -swirl <degrees>

| swirl image pixels about the center

| Degrees defines the tightness of the swirl.

| -text-font <name>

| font for writing fixed-width text

| Specifies the name of the preferred font to use in fixed (typewriter style) formatted text. The default is 14 point Courier.

| You can tag a font to specify whether it is a PostScript, TrueType, or OPTION1 font. For example, `Courier.ttf` is a TrueType font and `x:fixed` is OPTION1.

| -texture <filename>

| name of texture to tile onto the image background

| -threshold <value>{<green>,<blue>,<opacity>}{%}

| threshold the image

| Create an image such that any pixel sample that is equal to, or exceeds the threshold, is reassigned the maximum intensity otherwise the minimum intensity.

| If the green or blue value is omitted, these channels use the same value as the first one provided. If all three color values are the same, the result is a bi-level image. If the opacity threshold is omitted, OpaqueOpacity will be used and any partially transparent pixel will become fully transparent. If only a single 0 is provided, auto-thresholding will be performed.

| To generate an all-black or all-white image with the same dimensions as the input image, you can use

        gm convert -threshold 65535 in.png black.png
        gm convert -threshold 0,0 in.png white.png

| -tile <filename>

| tile image when filling a graphic primitive

| -tile <geometry>

| layout of images [montage]

| -title <string>

| assign title to displayed image [animate, display, montage]

| Use this option to assign a specific title to the image. This is assigned to the image window and is typically displayed in the window title bar. Optionally you can include the image filename, type, width, height, Exif data, or other image attribute by embedding special format characters described under the -format option.

| For example,

         -title "%m:%f %wx%h"

| produces an image title of `MIFF:bird.miff 512x480` for an image titled `bird.miff` and whose width is 512 and height is 480.

| -transform

| transform the image

| This option applies the transformation matrix from a previous -affine option.

        gm convert -affine 2,2,-2,2,0,0 -transform bird.ppm bird.jpg

| -transparent <color>

| make this color transparent within the image

| The color is specified using the format described under the -fill option.

| -treedepth <value>

| tree depth for the color reduction algorithm

| Normally, this integer value is zero or one. A value of zero or one causes the use of an optimal tree depth for the color reduction algorithm

| An optimal depth generally allows the best representation of the source image with the fastest computational speed and the least amount of memory. However, the default depth is inappropriate for some images. To assure the best representation, try values between 2 and 8 for this parameter. Refer to quantize for more details.

| The -colors or -monochrome option, or writing to an image format which requires color reduction, is required for this option to take effect.

| -trim

| trim an image

| This option removes any edges that are exactly the same color as the corner pixels. Use -fuzz to make -trim remove edges that are nearly the same color as the corner pixels.

| -type <type>

| the image type

| Choose from: Bilevel, Grayscale, Palette, PaletteMatte, TrueColor, TrueColorMatte, ColorSeparation, ColorSeparationMatte, or Optimize.

| Normally, when a format supports different subformats such as grayscale and truecolor, the encoder will try to choose an efficient subformat. The -type option can be used to overrride this behavior. For example, to prevent a JPEG from being written in grayscale format even though only gray pixels are present, use

        gm convert bird.pgm -type TrueColor bird.jpg

| Similarly, using `-type TrueColorMatte` will force the encoder to write an alpha channel even though the image is opaque, if the output format supports transparency.

| -update <seconds>

| detect when image file is modified and redisplay.

| Suppose that while you are displaying an image the file that is currently displayed is over-written. display will automatically detect that the input file has been changed and update the displayed image accordingly.

| -units <type>

| the units of image resolution

| Choose from: Undefined, PixelsPerInch, or PixelsPerCentimeter. This option is normally used in conjunction with the -density option.

| -unsharp <radius>{x<sigma>}{+<amount>}{+<threshold>}

| sharpen the image with an unsharp mask operator

| The -unsharp option sharpens an image. The image is convolved with a Gaussian operator of the given radius and standard deviation (sigma). For reasonable results, radius should be larger than sigma. Use a radius of 0 to have the method select a suitable radius.

| The parameters are:

radius
  The radius of the Gaussian, in pixels, not counting the center pixel (default 0).
sigma
  The standard deviation of the Gaussian, in pixels (default 1.0).
amount
  The percentage of the difference between the original and the blur image that is added back into the original (default 1.0).
threshold
  The threshold, as a fraction of MaxRGB, needed to apply the difference amount (default 0.05).

| -use-pixmap

| use the pixmap

| -verbose

| print detailed information about the image

| This information is printed: image scene number; image name; image size; the image class (DirectClass or PseudoClass); the total number of unique colors; and the number of seconds to read and transform the image. Refer to miff for a description of the image class.

| If -colors is also specified, the total unique colors in the image and color reduction error values are printed. Refer to quantize for a description of these values.

| -version

| print GraphicsMagick version string

| -view <string>

| FlashPix viewing parameters

| -virtual-pixel <method>

| specify contents of "virtual pixels"

| This option defines "virtual pixels" for use in operations that can access pixels outside the boundaries of an image.

| Choose from these methods:

Constant
  Use the image background color.
Edge
  Extend the edge pixel toward infinity (default).
Mirror
  Mirror the image.
Tile
  Tile the image.

| This option affects operations that use virtual pixels such as -blur, -sharpen, -wave, etc.

| -visual <type>

| animate images using this X visual type

| Choose from these visual classes:

         StaticGray
         GrayScale
         StaticColor
         PseudoColor
         TrueColor
         DirectColor
         default
         visual id

| The X server must support the visual you choose, otherwise an error occurs. If a visual is not specified, the visual class that can display the most simultaneous colors on the default screen is chosen.

| -watermark <brightness>x<saturation>

| percent brightness and saturation of a watermark

| -wave <amplitude>x<wavelength>

| alter an image along a sine wave

| Specify amplitude and wavelength of the wave.

| -white-point <x>,<y>

| chromaticity white point

| -window <id>

| make image the background of a window

| id can be a window id or name. Specify root to select X's root window as the target window.

| By default the image is tiled onto the background of the target window. If backdrop or -geometry are specified, the image is surrounded by the background color. Refer to X RESOURCES for details.

| The image will not display on the root window if the image has more unique colors than the target window colormap allows. Use -colors to reduce the number of colors.

| -window-group

| specify the window group

| -write <filename>

| write an image sequence [convert, composite]

| The image sequence following the -write filenameoption is written out, and then processing continues with the same image in its current state if there are additional options. To restore the image to its original state after writing it, use the +write filename option.

| -write <filename>

| write the image to a file [display]

| If filename already exists, you will be prompted as to whether it should be overwritten.

By default, the image is written in the format that it was read in as. To specify a particular image format, prefix filename with the image type and a colon (e.g., ps:image) or specify the image type as the filename suffix (e.g., image.ps). Specify file as - for standard output. If file has the extension .Z or .gz, the file size is compressed using compress or gzip respectively. Precede the image file name with | to pipe to a system command.

| Use -compress to specify the type of image compression.

| The equivalent X resource for this option is writeFilename (class WriteFilename). See X Resources for details.

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Environment

| COLUMNS

| Output screen width. Used when formatting text for the screen. Many Unix systems keep this shell variable up to date, but it may need to be explicitly exported in order for GraphicsMagick to see it.

| DISPLAY

| X11 display ID (host, display number, and screen in the form hostname:display.screen).

| HOME

| Location of user's home directory. GraphicsMagick searches for configuration files in $HOME/.magick if the directory exists. See MAGICK_CODER_MODULE_PATH, MAGICK_CONFIGURE_PATH, and MAGICK_FILTER_MODULE_PATH if more flexibility is needed.

| MAGICK_CODER_MODULE_PATH

Search path to use when searching for image format coder modules. This path allows the user to arbitrarily extend the image formats supported by GraphicsMagick by adding loadable modules to an arbitrary location rather than copying them into the GraphicsMagick installation directory. The formatting of the search path is similar to operating system search paths (i.e. colon delimited for Unix, and semi-colon delimited for Microsoft Windows). This user specified search path is used before trying the default search path.

| MAGICK_CONFIGURE_PATH

| Search path to use when searching for configuration (.mgk) files. The formatting of the search path is similar to operating system search paths (i.e. colon delimited for Unix, and semi-colon delimited for Microsoft Windows). This user specified search path is used before trying the default search path.

| MAGICK_DEBUG

| Debug options (see -debug for details)

| MAGICK_FILTER_MODULE_PATH

Search path to use when searching for filter process modules (invoked via -process). This path allows the user to arbitrarily extend GraphicsMagick's image processing functionality by adding loadable modules to an arbitrary location rather than copying them into the GraphicsMagick installation directory. The formatting of the search path is similar to operating system search paths (i.e. colon delimited for Unix, and semi-colon delimited for Microsoft Windows). This user specified search path is used before trying the default search path.

| MAGICK_FONT_PATH

| Directory where GraphicsMagick should look for TrueType and Postscript Type1 font files if the font file is not found in the current directory. It is preferred to define the available fonts via type.mgk rather than use MAGICK_FONT_PATH.

| MAGICK_HOME

| Path to top of GraphicsMagick installation directory. Only observed by "uninstalled" builds of GraphicsMagick which do not have their location hard-coded or set by an installer.

| MAGICK_LIMIT_DISK

| Maximum amount of disk space allowed for use by the pixel cache.

| MAGICK_LIMIT_FILES

| Maximum number of open files.

| MAGICK_LIMIT_MAP

| Maximum size of a memory map.

| MAGICK_LIMIT_MEMORY

| Maximum amount of memory to allocate from the heap.

| MAGICK_TMPDIR

| Path to directory where GraphicsMagick should write temporary files. The default is to use the system default, or the location set by TMPDIR.

| TMPDIR

| For POSIX-compatible systems (Unix-compatible), the path to the directory where all applications should write temporary files. Overridden by MAGICK_TMPDIR if it is set.

| TMP or TEMP

| For Microsoft Windows, the path to the directory where applications should write temporary files. Overridden by MAGICK_TMPDIR if it is set.

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Configuration Files

GraphicsMagick uses a number of XML format configuration files:

| colors.mgk

| colors configuration file

      <?xml version="1.0"?>
      <colormap>
        <color name="AliceBlue" red="240" green="248" blue="255"
               compliance="SVG, X11, XPM" />
      </colormap>

| delegates.mgk

| delegates configuration file

| log.mgk

| logging configuration file

      <?xml version="1.0"?>
      <magicklog>
        <log events="None" />
        <log output="stdout" />
        <log filename="Magick-%d.log" />
        <log generations="3" />
        <log limit="2000" />
        <log format="%t %r %u %p %m/%f/%l/%d:\n  %e"  />
      </magicklog>

| magic.mgk

| file header magic test configuration file

      <?xml version="1.0"?>
      <magicmap>
        <magic name="AVI" offset="0" target="RIFF" />
      </magicmap>

| modules.mgk

| loadable modules configuration file

      <?xml version="1.0"?>
      <modulemap>
        <module magick="8BIM" name="META" />
      </modulemap>

| type.mgk

| master type (fonts) configuration file

      <?xml version="1.0"?>
      <typemap>
        <include file="type-windows.mgk" />
        <type
          name="AvantGarde-Book"
          fullname="AvantGarde Book"
          family="AvantGarde"
          foundry="URW"
          weight="400"
          style="normal"
          stretch="normal"
          format="type1"
          metrics="/usr/local/share/ghostscript/fonts/a010013l.afm"
          glyphs="/usr/local/share/ghostscript/fonts/a010013l.pfb"
        />
      </typemap>

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Authors

| John Cristy, Bob Friesenhahn, Glenn Randers-Pehrson, William Radcliff, Leonard Rosenthol.

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Copyright

Copyright (C) 2002, 2003 GraphicsMagick Group, an organization dedicated to making software imaging solutions freely available.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files ("GraphicsMagick"), to deal in GraphicsMagick without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of GraphicsMagick, and to permit persons to whom GraphicsMagick is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of GraphicsMagick.

The software is provided "as is", without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and noninfringement. In no event shall GraphicsMagick Group be liable for any claim, damages or other liability, whether in an action of contract, tort or otherwise, arising from, out of or in connection with GraphicsMagick or the use or other dealings in GraphicsMagick.

Except as contained in this notice, the name of the GraphicsMagick Group shall not be used in advertising or otherwise to promote the sale, use or other dealings in GraphicsMagick without prior written authorization from the GraphicsMagick Group.

Additional copyrights and licenses apply to this software. You should have received a copy of Copyright.txt with this package, which describes additional copyrights and licenses which apply to this software; otherwise see http://www.graphicsmagick.org/www/Copyright.html.

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Copyright © GraphicsMagick Group 2002, 2003