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Auto-crops an image by shrinking the resolution or data window size to fit the image. This can be used to create smaller files by cutting out black space.
Synopsis
iautocrop [-b border_padding] [-c crop_value] [-f] [-i] [-n] [-p analyze_planes] [-q] [-r] infile [outfile]
where:
-b
Specify border padding of the crop area. Once the crop area is determined, an addition number of pixels can be added to each side, creating a slightly larger image. The default is zero.
-c
Specify the crop value. All values less that the crop_value are considered
to be safe to crop away. The default is zero.
-f
Fully crop the image. If a format supports a data window, normally the data window is set and the resolution left intact. This option will instead change the resolution of the image instead of setting the data window. Formats that do not support a data window are fully cropped by default, otherwise this is off by default.
-i
Information mode only. Print the crop region that would be applied rather than writing a file.
-n
Only create a new file if a cropping is needed. This is ignored if
-r (replace file) is used. If not specified, the source file is copied
to the destination file if the crop region is the same.
-p
Specify a list of planes to analyze when comparing pixel values to the
crop value. The default is C A (color and alpha). A * indicates that
all planes will be considered when determining the crop area.
-q
Quiet mode. Don’t print errors or warnings. -i will still print its output
if given, but other messages will be suppressed.
-r
Replace original file with the cropped version. outfile does not need to be given and will be ignored.
Description
Auto-crop shrinks the resolution or data window to the "interesting area" of
an image. This region is always rectangular. The pixels outside the area of
interest have values less than the crop_value (default 0). For multi-plane
images, such as .pic or .exr, the planes to analyze for the crop region can be
specified with the -p option (the default is analyze C and A).
Cropping can be done in-place (overwriting the image) with the -r option, or
to a different file if a second filename is given.
Some image formats support a data window, where the resolution of the image is
not the same as the area containing the image data. Often this is used as a
compression or performance feature. By default, these formats will have their
data window adjusted to match the auto-cropped region (unless -f, full crop, is
specified). Formats that do not support data windows will be fully cropped,
meaning their resolution will be changed to the crop area.
Examples
To adjust the data window of an EXR image to all color values zero and above:
iautocrop -p "C" example.exr cropped.exr
To replace an image with a fully cropped version of itself:
iautocrop -f -r image.pic
To adjust the data window of an EXR image with a small buffer area of 3 pixels around the image data:
iautocrop -b 3 -r example.exr
To print the crop region of all pixels at least 10% gray in a JPEG:
iautocrop -i -c 0.1 image.jpg