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pnmcrop—Crop a portable anymap
SYNOPSIS
pnmcrop [-white|-black][-left][-right][-top][-bottom][pnmfile]
DESCRIPTION
pnmcrop reads a portable anymap as input, removes edges that are the background color, and produces a portable anymap as output.
OPTIONS
By default, it makes a guess as to what the background color is. You can override the default with the -white and -black flags.
The options -left, -right, -top and -bottom restrict cropping to the sides specified. The default is to crop all sides of the image.
All flags can be abbreviated to their shortest unique prefix.
SEE ALSO
pnmcut(1), pnm(5)
AUTHOR
Copyright " 1989 by Jef Poskanzer.
25 February 1989
pnmcut—Cut a rectangle out of a portable anymap
SYNOPSIS
pnmcut x y width height [pnmfile]
DESCRIPTION
pnmcut reads a portable anymap as input, extracts the specified rectangle, and produces a portable anymap as output. The x and y can be negative, in which case they are interpreted relative to the right and bottom of the anymap, respectively.
SEE ALSO
pnm(5)
AUTHOR
Copyright " 1989 by Jef Poskanzer.
21 February 1989
pnmdepth—Change the maxval in a portable anymap
SYNOPSIS
pnmdepth newmaxval [pnmfile]
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DESCRIPTION
pnmdepth reads a portable anymap as input, scales all the pixel values, and writes out the image with the new maxval. Scaling the colors down to a smaller maxval will result in some loss of information.
Be careful of off-by-one errors when choosing the new maxval. For instance, if you want the color values to be five bits wide, use a maxval of 31, not 32.
SEE ALSO
pnm(5), ppmquant(1), ppmdither(1)
AUTHOR
Copyright " 1989, 1991 by Jef Poskanzer.
12 January 1991
pnmenlarge—Read a portable anymap and enlarge it N times
SYNOPSIS
pnmenlarge N [pnmfile]
DESCRIPTION
pnmenlarge reads a portable anymap as input, replicates its pixels N times, and produces a portable anymap as output.
pnmenlarge can only enlarge by integer factors. The slower but more general pnmscale can enlarge or reduce by arbitrary factors, and pbmreduce can reduce by integer factors, but only for bitmaps.
If you enlarge by a factor of 3 or more, you should probably add a pnmsmooth step; otherwise, you can see the original pixels in the resulting image.
SEE ALSO
pbmreduce(1), pnmscale(1), pnmsmooth(1), pnm(5)
AUTHOR
Copyright " 1989 by Jef Poskanzer.
26 February 1989
pnmfile—Describe a portable anymap
SYNOPSIS
pnmfile [pnmfile] ...
DESCRIPTION
pnmfile reads one or more portable anymaps as input and writes out short descriptions of the image type, size, and so on. This is mostly for use in shell scripts, so the format is not particularly pretty.
SEE ALSO
pnm(5), file(1)
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AUTHOR
Copyright " 1991 by Jef Poskanzer.
9 January 1991
pnmflip—Perform one or more flip operations on a portable anymap
SYNOPSIS
pnmflip [-leftright|-lr][-topbottom|-tb][-transpose|-xy][-rotate90|-r90|-ccw ] [-rotate270|-r270|-cw ][-rotate180|-r180][pnmfile]
DESCRIPTION
pnmflip reads a portable anymap as input, performs one or more flip operations in the order specified, and writes out a portable anymap.
OPTIONS
The flip operations available are left for right (-leftright or -lr); top for bottom (-topbottom or -tb); and transposition (-transpose or -xy). In addition, some canned concatenations are available: -rotate90 or -ccw is equivalent to -transpose -topbottom; -rotate270 or -cw is equivalent to -transpose -leftright; and -rotate180 is equivalent to -leftright -topbottom.
All flags can be abbreviated to their shortest unique prefix.
SEE ALSO
pnmrotate(1), pnm(5)
AUTHOR
Copyright" 1989 by Jef Poskanzer.
25 July 1989
pnmgamma—Perform gamma correction on a portable anymap
SYNOPSIS
pnmgamma value [pnmfile] pnmgamma redvalue greenvalue bluevalue [pnmfile]
DESCRIPTION
pnmgamma reads a portable anymap as input, performs gamma correction, and produces a portable anymap as output.
The arguments specify what gamma value(s) to use. A value of 1.0 leaves the image alone, less than 1 darkens it, and greater than 1 lightens it.
SEE ALSO
pnm(5)
AUTHOR
Copyright" 1991 by Bill Davidson and Jef Poskanzer.
12 January 1991
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pnmhistmap—Draw a histogram for a PGM or PPM file
SYNOPSIS
pnmhistmap [-black][-white][-max N][-verbose][pnmfile]
DESCRIPTION
pnmhistmap reads a portable anymap as input, although bitmap (PBM) input produces an error message and no image, and produces an image showing a histogram of the color (or gray) values in the input. A graymap (PGM) input produces a bitmap output. A pixmap (PPM) input produces pixmap output with three overlaid histograms: a red one for the red input, a green one for the green input, and a blue one for the blue input. The output is fixed in size: 256 pixels wide by 200 pixels high.
OPTIONS
| -black | Ignores the count of black pixels when scaling the histogram. |
| -white | Ignores the count of white pixels when scaling the histogram. |
The -black and -white options, which can be used separately or together, are useful for images with a large percentage of pixels whose value is zero or 255, which can cause the remaining histogram data to become unreadably small. Note that, for pixmap inputs, these options apply to all colors; if, for example, the input has a large number of bright-red areas, you will probably want to use the -white option.
| -max N | Force the scaling of the histogram to use N as the largest-count value. This is useful for inputs with a large percentage of single-color pixels that are not black or white. |
| -verbose | Report the progress of making the histogram, including the largest-count value used to scale the output. |
All flags can be abbreviated to their shortest unique prefix.
BUGS
Assumes maxval is always 255. Images with a smaller maxval will only use the lower-value side of the histogram. This can be overcome either by piping the input through pnmdepth 255 or by cutting and scaling the lower-value side of the histogram. Neither is a particularly elegant solution.
Should allow the output size to be specified.
SEE ALSO
pgmhist(1), ppmhist(1), pgm(5), ppm(5)
AUTHOR
Wilson H. Bent, Jr. (whb@usc.edu).
25 October 1993
pnmindex—Build a visual index of a bunch of anymaps
SYNOPSIS
pnmindex [-size N][-across N][-colors N][-black] pnmfile ...
DESCRIPTION
This script makes small versions of a bunch of anymaps, adds labels, and concatenates them together into a collage.