FBNORM

Section: User Commands (1)
Updated: 25-Jun-90
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NAME

fbnorm - normalize and adjust grayscale or color image

SYNOPSIS

fbnorm [ -b<val> -w<val> ] [ -<type> ] < image > image

DESCRIPTION

Extends the contrast range to a full 0 to 255. The arguments -b and -w given the percentage of the darkest pixels to map to black and lightest pixels to map to white.

For color images the default is to discard 0.5% each of the darkest and lightest pixels. Increasing the contrast beyond that may result in significant color artifacts (because the color values will be partially clipped).

OPTIONS

-b<num>,-w<num>: percentage black, white pixels to map to 0, 255. The default for grayscale images is to "discard" 2 percent of the black pixels and 1 percent of the white pixels. For color images both values default to 0.5 percent.
An alternate form is to specify two integers, which will then be linearly mapped to 0 and 255.

EXAMPLE

To normalize a grayscale FBM image using defaults:

% fbnorm < foo.fbm > bar.fbm

To increase contrast by discarding 10 percent of the black pixels and 5 percent of the white pixels:

% fbnorm -b10 -w5 < foo.fbm > bar.fbm

Or, if you know that you want 34 to map to 0 and 197 to map to 255, you can just type:

% fbnorm 34 197 < foo.fbm > bar.fbm

BUGS

None known.

HISTORY

Copyright (C) 1989,1990 by Michael Mauldin. Permission is granted to use this file in whole or in part for any purpose, educational, recreational or commercial, provided that this copyright notice is retained unchanged. This software is available to all free of charge by anonymous FTP and in the UUNET archives.

25-Jun-90 Michael Mauldin at Carnegie Mellon University: Release 1.0 mlm@cs.cmu.edu
07-Mar-89 Michael L. Mauldin at Carnegie Mellon University: Beta release (version 0.9) mlm@cs.cmu.edu

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Time: 01:28:16 GMT, December 05, 2024