BWSTAT(1)

NAME

bwstat - display statistics of a black and white image

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SYNOPSIS
DESCRIPTION
OPTIONS
EXAMPLES
METHOD
SEE ALSO
AUTHOR
COPYRIGHT
BUG REPORTS

SYNOPSIS

bwstat [-v] [file.bw]

bwstat reads a bw(5) format file (or standard input) and computes statistics of its pixel intensities. These include the total number of pixels, the file dimensions (assuming the image is square), minimum and maximum values, mean, median, mode (and its pixel count), variance, standard deviation, and skew.

OPTIONS

-v: Verbose mode. After the statistics, print the full histogram of pixel values: each intensity from 0 to 255, its pixel count, and its percentage of the total.
-h, -?: Print a usage message and exit.
file.bw: Optional input file. If not provided, bwstat reads from standard input.

EXAMPLES

Example 1. Summarize the intensity distribution of an image

bwstat moss.bw

Reports the pixel count, inferred square dimensions, minimum, maximum, mode, median, mean, standard deviation, variance, and skew for the intensities in moss.bw.

Example 2. Inspect a histogram piped from another tool

pix-bw scene.pix | bwstat -v

Converts a color pix(5) image to black and white with pix-bw(1) and pipes it straight into bwstat, which prints the statistics followed by the complete 0-255 histogram without writing an intermediate file.

METHOD

Since the pixel values are quantized (have discrete values from 0 to 255), the statistics can be computed from "lump sums" after building a histogram of the input. This results in a significant savings in computation while also making a single pass over the input file sufficient.