\
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.TH "Ppmflash User Manual" 0 "26 January 2003" "netpbm documentation"

.UN lbAB
.SH NAME
ppmflash - brighten a picture to approach white

.UN lbAC
.SH SYNOPSIS
ppmflash 
\fIflashfactor\fP
[\fIppmfile\fP]

.UN lbAD
.SH DESCRIPTION
.PP
This program is part of
.BR Netpbm (1)
.
.PP
\fBppmflash\fP reads a PPM image as input.  It changes the color of
each pixel to bring it a specified amount closer to white.  It
generates a PPM image of the result.
.PP
\fIflashfactor\fP is a real number between 0 and 1, inclusive.
\fBppmflash\fP increases the intensity of each RGB component by the
fraction \fIflashfactor\fP of the difference between the current
value and full intensity.  So if a pixel contains 60% full red, 10%
full green, and no blue and you specify 0.5 (half), \fBppmflash\fP
increases the red to 80% (because it was 40% from full intensity, so
it adds half of 40% to the original 60%), the green to 55%, and the
blue to 50%.
.PP
If \fIflashfactor\fP is zero, the output is identical to the input.
If \fIflashfactor\fP is one, the output is all white.
.PP
\fBppmbrighten\fP does a more normal kind of brightening.
\fBpamfunc\fP does a very simple brightening.  Both
\fBppmbrighten\fP and \fBpamfunc\fP can reduce brightness as well.
.PP
\fBpnmgamma\fP is another way people do a similar brightening, though
it isn't really intended for that.

.UN lbAE
.SH SEE ALSO
.BR ppmbrighten (1)

.BR pamfunc (1)
,
.BR pnmgamma (1)
,
.BR ppm (5)
,

.UN lbAF
.SH AUTHOR

Copyright (C) 1993 by Frank Neumann