Linux Commands Examples

A great documentation place for Linux commands

pbmreduce

read a portable bitmap and reduce it N times


see also : pnmenlarge - pnmscale - pgmtopbm

Synopsis

pbmreduce [-floyd|-fs|-threshold ] [-value val] N [pbmfile]


add an example, a script, a trick and tips

: email address (won't be displayed)
: name

Step 2

Thanks for this example ! - It will be moderated and published shortly.

Feel free to post other examples
Oops ! There is a tiny cockup. A damn 404 cockup. Please contact the loosy team who maintains and develops this wonderful site by clicking in the mighty feedback button on the side of the page. Say what happened. Thanks!

examples


no example yet ...

... Feel free to add your own example above to help other Linux-lovers !

description

Reads a portable bitmap as input. Reduces it by a factor of N, and produces a portable bitmap as output.

pbmreduce duplicates a lot of the functionality of pgmtopbm; you could do something like pnmscale | pgmtopbm, but pbmreduce is a lot faster.

pbmreduce can be used to "re-halftone" an image. Let’s say you have a scanner that only produces black&white, not grayscale, and it does a terrible job of halftoning (most b&w scanners fit this description). One way to fix the halftoning is to scan at the highest possible resolution, say 300 dpi, and then reduce by a factor of three or so using pbmreduce. You can even correct the brightness of an image, by using the -value flag.

options

By default, the halftoning after the reduction is done via boustrophedonic Floyd-Steinberg error diffusion; however, the -threshold flag can be used to specify simple thresholding. This gives better results when reducing line drawings.

The -value flag alters the thresholding value for all quantizations. It should be a real number between 0 and 1. Above 0.5 means darker images; below 0.5 means lighter.

All flags can be abbreviated to their shortest unique prefix.


see also

pnmenlarge , pnmscale , pgmtopbm , pbm


author

Copyright (C) 1988 by Jef Poskanzer.

How can this site be more helpful to YOU ?


give  feedback