CROP(1) CROP(1)
NAME
crop, iconv - frame, crop, and convert image
SYNOPSIS
crop [ -b red green blue ] [ -c red green blue ] [ -i n | -r
minx miny maxx maxy | -x dx | -y dy ] [ -t tx ty ] [ -b red
green blue ] [ file ]
iconv [ -u ] [ -c chandesc ] [ file ]
DESCRIPTION
Crop reads an image(6) file (default standard input), crops
it, and writes it as a compressed image(6) file to standard
output. There are two ways to specify a crop, by color
value or by geometry. They may be combined in a single run
of crop, in which case the color value crop will be done
first.
The -c option takes a red-green-blue triplet as described in
color(2). (For example, white is 255 255 255.) The corre-
sponding color is used as a value to be cut from the outer
edge of the picture; that is, the image is cropped to remove
the maximal outside rectangular strip in which every pixel
has the specified color.
The -i option insets the image rectangle by a constant
amount, n, which may be negative to generate extra space
around the image. The -x and -y options are similar, but
apply only to the x or y coordinates of the image.
The -r option specifies an exact rectangle.
The -t option specifies that the image's coordinate system
should be translated by tx, ty as the last step of process-
ing.
The -b option specifies a background color to be used to
fill around the image if the cropped image is larger than
the original, such as if the -i option is given a negative
argument. This can be used to draw a monochrome frame
around the image. The default color is black.
Iconv changes the format of pixels in the image file
(default standard input) and writes the resulting image to
standard output. Pixels in the image are converted accord-
ing to the channel descriptor chandesc, (see image(6)). For
example, to convert a 4-bit-per-pixel grey-scale image to an
8-bit-per-pixel color-mapped image, chandesc should be m8.
If chandesc is not given, the format is unchanged. The out-
put image is by default compressed; the -u option turns off
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CROP(1) CROP(1)
the compression.
EXAMPLE
To crop white edges off the picture and add a ten-pixel pink
border,
crop -c 255 255 255 -i -10 -b 255 150 150 imagefile > cropped
SOURCE
/sys/src/cmd/crop.c
SEE ALSO
image(6), color(2)
BUGS
Iconv should be able to do Floyd-Steinberg error diffusion
or dithering when converting to small image depths.
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