pgmnorm(1) [redhat man page]

pgmnorm(1)						      General Commands Manual							pgmnorm(1)

NAME

       pgmnorm - normalize the contrast in a portable graymap

SYNOPSIS

       pgmnorm [-bpercent N | -bvalue N] [-wpercent N | -wvalue N] [pgmfile]

DESCRIPTION

       Reads  a portable graymap as input.  Normalizes the contrast by forcing the lightest pixels to white, the darkest pixels to black, and lin-
       early rescaling the ones in between; and produces a portable graymap as output.

OPTIONS

       By default, the darkest 2 percent of all pixels are mapped to black, and the lightest 1 percent are mapped  to  white.	You  can  override
       these  percentages  by using the -bpercent and -wpercent flags, or you can specify the exact pixel values to be mapped by using the -bvalue
       and -wvalue flags.  Appropriate numbers for the flags can be gotten from the pgmhist tool.  If you just want to enhance the contrast,  then
       choose  values  at  elbows in the histogram; e.g. if value 29 represents 3% of the image but value 30 represents 20%, choose 30 for bvalue.
       If you want to lighten the image, then set bvalue to 0 and just fiddle with wvalue; similarly, to darken the image, set	wvalue	to  maxval
       and play with bvalue.

       All flags can be abbreviated to their shortest unique prefix.

SEE ALSO

       pgmhist(1), ppmnorm(1), pgm(5)

AUTHOR

       Partially based on the fbnorm filter in Michael Mauldin's "Fuzzy Pixmap" package.

       Copyright (C) 1989 by Jef Poskanzer.

								 28 February 1989							pgmnorm(1)

ppmnorm(1)						      General Commands Manual							ppmnorm(1)

NAME

       ppmnorm - normalize the contrast in a portable pixmap

SYNOPSIS

       ppmnorm [-bpercent N | -bvalue N] [-wpercent N | -wvalue N] [ppmfile]

DESCRIPTION

       Reads  a  portable pixmap as input.  Normalizes the contrast by forcing the lightest pixels to white, the darkest pixels to black, and lin-
       early rescaling the ones in between; and produces a portable pixmap as output.

       Works by computing the realtive grey-level of each pixel a'la ppmtopgm, and uses those values to scale the RGB levels.  Note that  this	is
       different from using pgmnorm on the individual red, green, and blue greymaps (as produced by ppmtorgb3) and recombining them.

OPTIONS

       By  default,  the  darkest  2  percent of all pixels are mapped to black, and the lightest 1 percent are mapped to white.  You can override
       these percentages by using the -bpercent and -wpercent flags, or you can specify the exact pixel values to be mapped by using  the  -bvalue
       and  -wvalue flags.  Appropriate numbers for the flags can be gotten from the ppmhist tool.  If you just want to enhance the contrast, then
       choose values at elbows in the histogram; e.g. if value 29 represents 3% of the image but value 30 represents 20%, choose  30  for  bvalue.
       If  you	want  to lighten the image, then set bvalue to 0 and just fiddle with wvalue; similarly, to darken the image, set wvalue to maxval
       and play with bvalue.

       All flags can be abbreviated to their shortest unique prefix.

SEE ALSO

       pgmnorm(1), ppmhist(1), ppm(5)

AUTHOR

       Wilson H. Bent. Jr. (whb@usc.edu), heavily based on the pgmnorm filter by Jef Poskanzer.

								  7 October 1993							ppmnorm(1)