NAME
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gm - GraphicsMagick command-line utilities to create, edit, or convert images
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Contents
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Synopsis
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gm animate [ options ... ] file [ [
options ... ] file ... ]
compare [ options ... ] reference-image
[ options ... ] compare-image
[ options ... ]
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
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Description
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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 |
| 8BIMTEXT | *rw- | Photoshop resource format |
| 8BIMWTEXT | *rw- | Photoshop resource format |
| 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 |
| BMP2 | *-w- | Microsoft Windows bitmap image v2 |
| BMP3 | *-w- | Microsoft Windows bitmap image v3 |
| CACHE | *--- | Magick Persistent Cache image format |
| CAPTION | *r-- | Caption (requires separate size info) |
| CIN | *rw- | Kodak Cineon Format |
| 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) |
| CUR | *r-- | Microsoft Cursor Icon |
| CUT | *r-- | DR Halo |
| DCM | *r-- | Digital Imaging and Communications in |
| | | Medicine image |
| DCX | *rw+ | ZSoft IBM PC multi-page Paintbrush |
| DPS | *r-- | Display PostScript |
| DPX | *rw- | 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 MS-DOS |
| | | TIFF preview |
| EPT2 | *rw- | Adobe Level II Encapsulated PostScript |
| | | with MS-DOS TIFF preview |
| EPT3 | *rw- | Adobe Level III Encapsulated PostScript |
| | | with MS-DOS TIFF preview |
| EXIF | *rw- | Exif digital camera binary data |
| FAX | *rw+ | Group 3 FAX |
| FITS | *rw- | Flexible Image Transport System |
| FPX | *rw- | FlashPix Format |
| 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 |
| GRAY | *rw+ | Raw gray samples (8 or 16 bits, |
| | | depending on the image depth) |
| 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 |
| ICB | *rw+ | Truevision Targa image |
| ICC | *rw- | ICC Color Profile |
| ICM | *rw- | ICC Color Profile |
| ICO | *r-- | Microsoft icon |
| ICON | *r-- | Microsoft icon |
| IPTC | *rw- | IPTC Newsphoto |
| IPTCTEXT | *rw- | IPTC Newsphoto text format |
| IPTCWTEXT | *rw- | IPTC Newsphoto wide text format |
| JBG | *rw+ | Joint Bi-level Image experts Group |
| | | interchange format |
| JBIG | *rw+ | Joint Bi-level Image experts Group |
| | | interchange format |
| JNG | *rw- | JPEG Network Graphics |
| 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 and indices |
| MAT | *r-- | MATLAB image format |
| MATTE | *-w+ | MATTE format |
| MIFF | *rw+ | Magick Image File 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 |
| MSL | *r-- | Magick Scripting Language |
| MTV | *rw+ | MTV Raytracing image format |
| MVG | *rw- | Magick Vector Graphics |
| 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 |
| 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 | *rw+ | Pilot Image Format |
| PDF | *rw+ | Portable Document Format |
| PFA | *r-- | TrueType font |
| PFB | *r-- | TrueType font |
| PGM | *rw+ | Portable graymap format (gray scale) |
| PGX | *r-- | JPEG-2000 VM Format |
| PICON | *rw- | Personal Icon |
| PICT | *rw- | Apple Macintosh QuickDraw/PICT |
| PIX | *r-- | Alias/Wavefront RLE image format |
| PLASMA | *r-- | Plasma fractal image |
| PNG | *rw- | Portable Network Graphics |
| PNG24 | *rw- | Portable Network Graphics, 24 bit RGB |
| | | opaque only |
| PNG32 | *rw- | Portable Network Graphics, 32 bit RGBA |
| | | semitransparency OK |
| PNG8 | *rw- | Portable Network Graphics, 8-bit |
| | | indexed, binary transparency only |
| 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, 16 |
| | | or 32 bits, depending on the image depth) |
| RGBA | *rw+ | Raw red, green, blue, and matte samples |
| | | (8, 16, or 32 bits, depending on the image |
| | | depth) |
| RLA | *r-- | Alias/Wavefront image |
| RLE | *r-- | Utah Run length encoded 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 |
| TIFF | *rw+ | Tagged Image File Format |
| TILE | *r-- | Tile image with a texture |
| TIM | *r-- | PSX TIM |
| TOPOL | *r-- | TOPOL X Image |
| 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 |
| XMP | *rw- | Adobe XML metadata |
| 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 or 4:2:2 (8-bit only) |
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| 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.
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Files and Formats
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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
format specification in the file name. For example,
image%02d.miff
writes files image00.miff, image01.miff, etc. Only a single
specification is allowed within an output filename. If more than one
specification is present, it will be ignored.
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.
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Back to Contents
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Options
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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, compare,
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%".
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-adjoin
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| join images into a single multi-image file |
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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. |
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-affine <matrix>
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This option provides a transform matrix {sx,rx,ry,sy,tx,ty} for
use by subsequent -draw or -transform options. |
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-antialias
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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. |
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-append
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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. |
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-authenticate <string>
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| decrypt image with this password |
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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. |
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-average
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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. |
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-backdrop
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| display the image centered on a backdrop. |
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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). |
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-background <color>
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The color is specified using the format described under the -fill
option. |
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-black-threshold red[,green][,blue][,opacity]
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| pixels below the threshold become black |
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Use -black-threshold to set pixels with values below the specified
threshold to minimum value (black). If only one value is supplied, or the
red, green, and blue values are identical, then intensity thresholding is
used. If the color threshold values are not identical then channel-based
thresholding is used, and color distortion will occur. Specify a negative
value (e.g. -1) if you want a channel to be ignored but you do want to
threshold a channel later in the list. If a percent (%) symbol is
appended, then the values are treated as a percentage of maximum
range. |
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-blue-primary <x>,<y>
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| blue chromaticity primary point |
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-blur <radius>{x<sigma>}
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| blur the image with a Gaussian operator |
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Blur with the given radius and
standard deviation (sigma). |
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-border <width>x<height>
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| surround the image with a border of color |
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See -geometry for details
about the geometry specification. |
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-bordercolor <color>
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The color is specified using the format described under the -fill
option. |
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-borderwidth <geometry>
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-box <color>
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| set the color of the annotation bounding box |
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The color is specified using the format described under the -fill
option. |
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See -draw for further
details. |
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-channel <type>
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Choose from: Red, Green, Blue, Opacity,
Matte, Cyan, Magenta, Yellow, Black,
or Gray. |
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Use this option to extract a particular channel from the image.
Opacity,
for example, is useful for extracting the opacity values from an image. |
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-charcoal <factor>
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| simulate a charcoal drawing |
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-chop <width>x<height>{+-}<x>{+-}<y>{%}
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| remove pixels from the interior of an image |
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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. |
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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. |
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The -chop option removes entire rows and columns,
and moves the remaining corner blocks leftward and upward to close the gaps. |
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-clip
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| apply the clipping path, if one is present |
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If a clipping path is present, it will be applied to subsequent operations. |
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For example, if you type the following command: |
gm convert -clip -negate cockatoo.tif negated.tif
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only the pixels within the clipping path are negated. |
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The -clip feature requires the XML library. If the XML library
is not present, the option is ignored. |
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-coalesce
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| merge a sequence of images |
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Each image N in the sequence after Image 0 is replaced with the image
created by flattening images 0 through N. |
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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. |
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-colorize <value>
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| colorize the image with the pen color |
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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). |
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-colormap <type>
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Choose between shared or private. |
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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. |
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-colors <value>
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| preferred number of colors in the image |
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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. |
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Note, options -dither, -colorspace, and -treedepth
affect the color reduction algorithm. |
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-colorspace <value>
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Choices are:
CineonLog, CMYK, GRAY, HSL, HWB,
OHTA, RGB, Rec601Luma, Rec709Luma,
Rec601YCbCr, Rec709YCbCr, Transparent, XYZ,
YCbCr, YIQ, YPbPr, or YUV. |
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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. |
| Two gray colorspaces are supported. The Rec601Luma space is
based on the recommendations for legacy NTSC television (ITU-R BT.601-5).
The Rec709Luma space is based on the recommendations for HDTV
(Rec. ITU-R BT.709-5) and is suitable for suitable for use with computer
graphics, and for contemporary CRT displays. The GRAY colorspace
currently selects the Rec601Luma colorspace by default for
backwards compatibly reasons. This default may be re-considered in the
future.
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| Two YCbCr colorspaces are supported. The Rec601YCbCr space is
based on the recommendations for legacy NTSC television (ITU-R BT.601-5). The
Rec709CbCr space is based on the recommendations for HDTV (Rec.
ITU-R BT.709-5) and is suitable for suitable for use with computer
graphics, and for contemporary CRT displays. The YCbCr colorspace
specification is equivalent toRec601YCbCr.
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The Transparent color space behaves uniquely in that it preserves
the matte channel of the image if it exists. |
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The -colors or -monochrome option, or saving to a file
format which requires color reduction, is required for this option to
take effect. |
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-comment <string>
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| annotate an image with a comment |
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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. |
-comment "%m:%f %wx%h"
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produces an image comment of MIFF:bird.miff 512x480 for an image
titled bird.miff and whose width is 512 and height is 480. |
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If the first character of string is @, the image comment
is read from a file titled by the remaining characters in the string. |
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-compose <operator>
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| the type of image composition |
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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). |
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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. |
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By default, the Over composite operator is used. The following
composite operators are available: |
Over
In
Out
Atop
Xor
Plus
Minus
Add
Subtract
Difference
Divide
Multiply
Bumpmap
Copy
CopyRed
CopyGreen
CopyBlue
CopyOpacity
CopyCyan
CopyMagenta
CopyYellow
CopyBlack
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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.
- Divide
- The result of change-image / base-image. This is useful
for improving the readability of text on unevenly illuminated photos (by
using a gaussian blurred copy of change-image as base-image).
- 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.
- CopyCyan
- The resulting image is the cyan channel in base-image replaced
with the cyan channel in change-image. The other channels are
copied untouched. Use of this operator requires that base-image be in
CMYK(A) colorspace.
- CopyMagenta
- The resulting image is the magenta channel in base-image
replaced with the magenta channel in change-image. The other
channels are copied untouched. Use of this operator requires that
base-image be in CMYK(A) colorspace.
- CopyYellow
- The resulting image is the yellow channel in base-image
replaced with the yellow channel in change-image. The other
channels are copied untouched. Use of this operator requires that
base-image be in CMYK(A) colorspace.
- CopyBlack
- The resulting image is the black channel in base-image
replaced with the black channel in change-image. The other
channels are copied untouched. Use of this operator requires that
base-image be in CMYK(A) colorspace. If change-image is not in CMYK
space, then the change-image pixel intensities are used.
|
-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. |
|
"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 the DPX, 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 floating point
values, 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. |
|
-create-directories
|
| create output directory if required |
|
Use this option with -output-directory if the input paths contain
subdirectories and it is desired to create similar subdirectories in the
output directory. Without this option, mogrify will fail if the
required output directory does not exist. |
|
-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>
|
|
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: |
- cineon:colorspace={rgb|cineonlog}
- Use the cineon:colorspace option when reading a Cineon file to
specify the colorspace the Cineon file uses. This overrides the colorspace
type implied by the DPX header (if any).
- dpx:bits-per-sample=<value>
- If the dpx:bits-per-sample key is defined, GraphicsMagick will write
DPX images with the specified bits per sample, overriding any existing
depth value. If this option is not specified, then the value is based on
the existing image depth value from the original image file. The DPX
standard supports bits per sample values of 1, 8, 10, 12, and 16. Many
DPX readers demand a sample size of 10 bits with type A padding (see
below).
- dpx:colorspace={rgb|cineonlog}
- Use the dpx:colorspace option when reading a DPX file to
specify the colorspace the DPX file uses. This overrides the colorspace
type implied by the DPX header (if any).
- dpx:packing-method={packed|a|b|lsbpad|msbpad}
- DPX samples are output within 32-bit words. They may be tightly
packed end-to-end within the words ("packed"), padded with null bits to
the right of the sample ("a" or "lsbpad), or padded with null bits to the
left of the sample ("b" or "msbpad"). This option only has an effect for
sample sizes of 10 or 12 bits. If samples are not packed, the DPX
standard recommends type A padding. Many DPX readers demand a sample size
of 10 bits with type A padding.
- dpx:pixel-endian={lsb|msb}
- Allows the user to specify the endian order of the pixels when
reading or writing the DPX files. Sometimes this is useful if the file is
(or must be) written incorrectly so that the file header and the pixels
use different endianness.
- dpx:swap-samples={true|false}
- GraphicsMagick strives to adhere to the DPX standard but certain
aspects of the standard can be quite confusing. As a result, some 10-bit
DPX files have Red and Blue interchanged, or Cb and Cr interchanged due
to an different interpretation of the standard, or getting the wires
crossed. The swap-samples option may be supplied when reading or writing
in order to read or write using the necessary sample order.
- 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:dct-method=<value>
- Selects the IJG JPEG library DCT encoding implementation to use. The
encoding implementations vary in speed and encoding error. The available
choices for value are islow, ifast, float,
default and fastest. Note that fastest might not
necessarily be fastest on your CPU, depending on the choices made when
the JPEG library was built and how your CPU behaves.
- jpeg:optimize-coding={true|false}
-
Selects if huffman encoding should be used. Huffman encoding is enabled
by default, but may be disabled for very large images since it encoding
requires that the entire image be buffered in memory. Huffman encoding
produces smaller JPEG files at the expense of added compression time and
memory consumption.
- 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:alpha={unspecified|associated|unassociated}
- Specify the TIFF alpha channel type when reading or writing TIFF files,
overriding the normal value. The default alpha channel type for new files
is associated alpha. Existing alpha settings are preserved when
converting from one TIFF file to another. When a TIFF file uses
associated alpha, the image pixels are pre-multiplied (i.e. altered) with
the alpha channel. Files with "associated" alpha appear as if they were
alpha composited on a black background when the matte channel is
disabled. If the unassociated alpha type is selected, then the alpha
channel is saved without altering the pixels. Photoshop recognizes
associated alpha as transparency information, if the file is saved with
unassociated alpha, the alpha information is loaded as an independent
channel. Note that for many years, ImageMagick and GraphicsMagick marked
TIFF files as using associated alpha, without properly pre-multiplying
the pixels.
- tiff:fill-order={msb2lsb|lsb2msb}
- If the tiff:fill-order key is defined, GraphicsMagick will use it to
determine the bit fill order used while writing TIFF files. The normal default
is "msb2lsb", which matches the native bit order of all modern CPUs. The
only exception to this is when Group3 or Group4 FAX compression is
requested since FAX machines send data in bit-reversed order and
therefore RFC 2301 recommends using reverse order.
- tiff:sample-format={unsigned|ieeefp}
- If the tiff:sample-format key is defined, GraphicsMagick will use it to
determine the sample format used while writing TIFF files. The default is
"unsigned". Specify "ieeefp" in order to write floating-point TIFF
files with float (32-bit) or double (64-bit) values. Use the
tiff:bits-per-sample define to determine the type of floating-point value
to use.
- tiff:max-sample-value=<value>
- If the tiff:max-sample-value key is defined, GraphicsMagick will use the
assigned value as the maximum floating point value while reading or
writing IEEE floating point TIFFs. Otherwise the maximum value is 1.0 or
the value obtained from the file's SMaxSampleValue tag (if present). The
floating point data is currently not scanned in advance to determine a
best maximum sample value so if the range is not 1.0, or the
SMaxSampleValue tag is not present, it may be necessary to
(intelligently) use this parameter to properly read a file.
- tiff:min-sample-value=<value>
- If the tiff:min-sample-value key is defined, GraphicsMagick will use the
assigned value as the minimum floating point value while reading or
writing IEEE floating point TIFFs. Otherwise the minimum value is 0.0 or
the value obtained from the file's SMinSampleValue tag (if present).
- tiff:bits-per-sample=<value>
- If the tiff:bits-per-sample key is defined, GraphicsMagick will write
images with the specified bits per sample, overriding any existing depth
value. The range of the value is 1 to 32 when the default 'unsigned'
format is written, or 32/64 if IEEEFP format is written. Please note that
the baseline TIFF 6.0 specification only requires readers to handle
certain powers of two, and the values to be handled depend on the nature
of the image (e.g. colormapped, grayscale, RGB, CMYK).
- 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. This option should not normally be used.
- tiff:rows-per-strip=<value>
- Allows the user to specify the number of rows per TIFF strip. Ignored
if using tiles or JPEG compression.
- tiff:strip-per-page=true
- Requests that the image is written in a single TIFF strip. This is
normally the default when group3 or group4 compression is requested
within reasonable limits. Requesting a single strip for large images may
result in failure due to resource consumption in the writer or reader.
- tiff:tile
- Enable writing tiled TIFF (rather than stripped) using the default tile
size. Tiled TIFF organizes the image as an array of smaller images
(tiles) in order to enable random access.
- tiff:tile-geometry=<width>x<height>
- Specify the tile size to use while writing tiled TIFF. Width and
height should be a multiple of 16. If the value is not a multiple of 16,
then it will be rounded down. Enables tiled TIFF if it has not already
been enabled. GraphicsMagick does not use tiled storage internally so
tiles need to be converted back and forth from the internal
scanline-oriented storage to tile-oriented storage. Testing with typical
RGB images shows that useful square tile size values range from 128x128
to 1024x1024. Large images which require using a disk-based pixel cache
benefit from large tile sizes while images which fit in memory work well
with smaller tile sizes.
- tiff:tile-width=<width>
- Specify the tile width to use while writing tiled TIFF. The tile height
is then defaulted to an appropriate size. Width should be a multiple of
16. If the value is not a multiple of 16, then it will be rounded down.
Enables tiled TIFF if it has not already been enabled.
- tiff:tile-height=<height>
- Specify the tile height to use while writing tiled TIFF. The tile width
is then defaulted to an appropriate size. Height should be a multiple of
16. If the value is not a multiple of 16, then it will be rounded down.
Enables tiled TIFF if it has not already been enabled.
|
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>
|
|
This is the number of bits of color to preserve in the image. Any value
between 1 and QuantumDepth (build option) may be specified,
although 8 or 16 are the most common values. 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. |
| The depth option is applied to the pixels immediately so it may be
used as a form of simple compression by discarding the least significant
bits. Reducing the depth in advance may speed up color quantization, and
help create smaller file sizes when using a compression algorithm like
LZW or ZIP. |
|
-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>
|
|
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
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. |
-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. |
|
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>
|
|
-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 |
|
MSB indicates big-endian (e.g. SPARC, Motorola 68K) while LSB
indicates little-endian (e.g. Intel 'x86, VAX) byte ordering. This
option currently only influences the output of the DPX and TIFF
writers. |
|
Use +endian to revert to unspecified endianness. |
|
-enhance
|
| apply a digital filter to enhance a noisy image |
|
-equalize
|
| perform histogram equalization to the image |
|
-file <filename>
|
| write annotated difference image to file |
|
If -file is specified, then an annotated difference image is
generated and written to the specified file. Pixels which differ between
the reference and compare images are modified from those in
the compare image so that the changed pixels become more obvious.
Some images may require use of an alternative highlight style (see
-highlight-style) or highlight color (see -highlight-color)
before the changes are obvious. |
|
-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. |
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 (ordered by approximate increasing CPU
time): |
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
|
|
reflect the scanlines in the vertical direction. |
|
-flop
|
|
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 X11
font. For example, Arial.ttf is a TrueType font, ps:helvetica
is PostScript, and x:fixed is X11. |
| |