Options (general):

--help

Print help message

-v

Verbose status messages

-q

Quiet mode (turn verbose off)

--runstats

Print runtime statistics

-a

Do operations on all subimages/miplevels

--info

Print resolution and metadata on all inputs

--metamatch %s

Regex: which metadata is printed with -info -v

--no-metamatch %s

Regex: which metadata is excluded with -info -v

--stats

Print pixel statistics on all inputs

--hash

Print SHA-1 hash of each input image

--colorcount %s

Count of how many pixels have the given color (argument: color;color;...) (optional args: eps=color)

--rangecheck %s %s

Count of how many pixels are outside the low and high color arguments (each is a comma-separated color value list)

--no-clobber

Do not overwrite existing files

--threads %d

Number of threads (default 0 == #cores)

--frames %s

Frame range for '#' wildcards

--framepadding %d

Frame number padding digits

Commands that write images:

-o %s

Output the current image to the named file

Options that affect subsequent image output:

-d %s

'-d TYPE' sets the output data format of all channels, '-d CHAN=TYPE' overrides a single named channel (multiple -d args are allowed).
Data types include: uint8, sint8, uint10, uint12, uint16, sint16, half, float, double

--scanline

Output scanline images

--tile %d %d

Output tiled images (tilewidth, tileheight)

--compression %s

Set the compression method

--quality %d

Set the compression quality, 1-100

--planarconfig %s

Force planarconfig (contig, separate, default)

--adjust-time

Adjust file times to match DateTime metadata

--noautocrop

Do not automatically crop images whose formats don't support separate pixel data and full/display windows

--autotrim

Automatically trim black borders upon output to file formats that support separate pixel data and full/display windows

Options that change current image metadata (but not pixel values):

--attrib %s %s

Sets metadata attribute (name, value)

--sattrib %s %s

Sets string metadata attribute (name, value)

--caption %s

Sets caption (ImageDescription metadata)

--keyword %s

Add a keyword

--clear-keywords

Clear all keywords

--orientation %d

Set the assumed orientation

--rotcw

Rotate orientation 90 deg clockwise

--rotccw

Rotate orientation 90 deg counter-clockwise

--rot180

Rotate orientation 180 deg

--origin %s

Set the pixel data window origin (e.g. +20+10)

--fullsize %s

Set the display window (e.g., 1920x1080, 1024x768+100+0, -20-30)

--fullpixels

Set the 'full' image range to be the pixel data window

--chnames %s

Set the channel names (comma-separated)

Options that affect subsequent actions:

--fail %g

Failure threshold difference (0.000001)

--failpercent %g

Allow this percentage of failures in diff (0)

--hardfail %g

Fail diff if any one pixel exceeds this error (infinity)

--warn %g

Warning threshold difference (0.00001)

--warnpercent %g

Allow this percentage of warnings in diff (0)

--hardwarn %g

Warn if any one pixel difference exceeds this error (infinity)

Actions:

--create %s %d

Create a blank image (args: geom, channels)

--pattern %s %s %d

Create a patterned image (args: pattern, geom, channels)

--kernel %s %s

Create a centered convolution kernel (args: name, geom)

--capture

Capture an image (options: camera=%d)

--diff

Print report on the difference of two images (modified by --fail, --failpercent, --hardfail, --warn, --warnpercent --hardwarn)

--add

Add two images

--sub

Subtract two images

--abs

Take the absolute value of the image pixels

--mul

Multiply two images

--cmul %s

Multiply the image values by a scalar or per-channel constants (e.g.: 0.5 or 1,1.25,0.5)

--cadd %s

Add to all channels a scalar or per-channel constants (e.g.: 0.5 or 1,1.25,0.5)

--chsum

Turn into 1-channel image by summing channels (options: weight=r,g,...)

--paste %s

Paste fg over bg at the given position (e.g., +100+50)

--mosaic %s

Assemble images into a mosaic (arg: WxH; options: pad=0)

--over

'Over' composite of two images

--zover

Depth composite two images with Z channels (options: zeroisinf=%d)

--histogram %s %d

Histogram one channel (options: cumulative=0)

--flip

Flip the image vertically (top<->bottom)

--flop

Flop the image horizontally (left<->right)

--flipflop

Flip and flop the image (180 degree rotation)

--transpose

Transpose the image

--cshift %s

Circular shift the image (e.g.: +20-10)

--crop %s

Set pixel data resolution and offset, cropping or padding if necessary (WxH+X+Y or xmin,ymin,xmax,ymax)

--croptofull

Crop or pad to make pixel data region match the "full" region

--resample %s

Resample (640x480, 50%)

--resize %s

Resize (640x480, 50%) (optional args: filter=%s)

--fit %s

Resize to fit within a window size (optional args: filter=%s, pad=%d)

--convolve

Convolve with a kernel

--blur %s

Blur the image (arg: WxH; options: kernel=name)

--unsharp

Unsharp mask (options: kernel=gaussian, width=3, contrast=1, threshold=0)

--fft

Take the FFT of the image

--ifft

Take the inverse FFT of the image

--fixnan %s

Fix NaN/Inf values in the image (options: none, black, box3)

--fillholes

Fill in holes (where alpha is not 1)

--fill %s

Fill a region (options: color=)

--clamp

Clamp values (options: min=..., max=..., clampalpha=0)

--rangecompress

Compress the range of pixel values > 1 with a log scale (options: luma=0|1)

--rangeexpand

Un-rangecompress pixel values > 1 (options: luma=0|1)

--text %s

Render text into the current image (options: x=, y=, size=, color=)

Image stack manipulation:

--ch %s

Select or shuffle channels (e.g., "R,G,B", "B,G,R", "2,3,4")

--chappend

Append the channels of the last two images

--unmip

Discard all but the top level of a MIPmap

--selectmip %d

Select just one MIP level (0 = highest res)

--subimage %d

Select just one subimage

--pop

Throw away the current image

--dup

Duplicate the current image (push a copy onto the stack)

--swap

Swap the top two images on the stack.

Color management:

--iscolorspace %s

Set the assumed color space (without altering pixels)

--tocolorspace %s

Convert the current image's pixels to a named color space

--colorconvert %s %s

Convert pixels from 'src' to 'dst' color space (without regard to its previous interpretation)

--ociolook %s

Apply the named OCIO look (optional args: from=, to=, inverse=, key=, value=)

--unpremult

Divide all color channels of the current image by the alpha to "un-premultiply"

--premult

Multiply all color channels of the current image by the alpha

Known color spaces: "linear", "sRGB", "Rec709"