Pgmhist User Manual(0) Pgmhist User Manual(0)NAMEpgmhist - print a histogram of the values in a PGM image
SYNOPSISpgmhist
[-median, -quartile, -decile]
[-machine]
[pgmfile]
DESCRIPTION
This program is part of Netpbm(1)pgmhist reads a PGM image as input and prints a histogram of the gray
values or other gray value distribution metrics.
If you specify none of -median, -quartile, or -decile, pgmhist prints a
complete histogram showing how many pixels of each possible gray value
exist in the image. Along with each gray value, it tells you how many
pixels are more black and more white that it.
-median, -quartile, and -decile options cause pgmhist instead to print
the indicated quantiles. Each quantile is a gray value that actually
appears in the image (as opposed to fractional values that are some‐
times used for quantiles). The 3rd quartile is the least gray value
for which at least 75% of the pixels are as dark or darker than it.
The 4th quartile is the brightest gray value that appears in the image.
OPTIONS
You must specify exactly one of the ramp type options.
-median
This option causes pgmhist to print the median gray value.
You may specify at most one of -median, -quartile, and -decile.
This option was new in Neptbm 10.61 (December 2012).
-quartile
This option causes pgmhist to print the four quartile gray
value.
You may specify at most one of -median, -quartile, and -decile.
This option was new in Neptbm 10.61 (December 2012).
-decile
This option causes pgmhist to print the ten decile gray value.
You may specify at most one of -median, -quartile, and -decile.
This option was new in Neptbm 10.61 (December 2012).
-machine
This option causes pgmhist to print the information in a way
easily digestible by a machine as opposed to a human.
For the quantiles, there is one line per quantile, in quantile
order, and it consists of the gray value of the quantile in dec‐
imal with no leading zeroes.
For the full histogram output, it consists of one line per pos‐
sible gray value (whether that value appears in the image or
not), in order of the gray values. The line consists of two
tokens separated by a space. The first is the gray value; the
second is the number of pixels in the image that have that gray
value. Both are decimal numbers without leading zeroes.
This option was new in Neptbm 10.61 (December 2012).
SEE ALSOpnmnorm(1) , ppmhist(1)pgm(1) ,
AUTHOR
Copyright (C) 1989 by Jef Poskanzer.
netpbm documentation 2 December 2012 Pgmhist User Manual(0)
