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GAMMAADJUST

Section: User Commands (1)
Updated: 16 Mar 1998
Index

NAME

gammaAdjust - Simple gamma correction

SYNTAX

gammaAdjust [-adjust <value>] <infile> <outfile>

DESCRIPTION

A simple gamma corretion to make imagesdarker or brigter. The adjustparameter must bein the range -1.0 (much darker) to 1 (much brighter).If adjust = 0.0 the band is not changed.

If adjust > 0:
a= adjust**2/0.16;
b= 255.0 / log(a*255.0+1.0);
c= 256.0/a * log(1.0 + (exp(a) - 1.0) * i / 256.0);
col[i] = c;

If adjust < 0;
a= adjust**2/0.16;
b= 255.0 / log(a*255.0+1.0);
c= 256.0/a * log(1.0 + (exp(a) - 1.0) * (255-i) / 256.0);
col[i] = 255-c;

RETURN VALUE

0 - OK
2 - Bad pixtype
3 - Bad size

RESTRICTIONS

Works on unsigned byte bands only.

AUTHOR

Otto Milvang

EXAMPLES

gammaAdjust -adjust 0.4 file.img | biff2ps - | lpr

ID

$Id: gammaAdjust.c,v 1.16 1996/11/08 14:03:58 svein Exp $

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