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RedHat 9 (Linux i386) - man page for pgmtoppm (redhat section 1)

pgmtoppm(1)			     General Commands Manual			      pgmtoppm(1)

       pgmtoppm - colorize a PGM (grayscale) image into a PGM (color) image

       pgmtoppm colorspec [pgmfile]
       pgmtoppm colorspec1-colorspec2 [pgmfile]
       pgmtoppm -map mapfile [pgmfile]

       Reads  a  PGM  as  input.  Produces a PPM file as output with a specific color assigned to
       each gray value in the input.

       If you specify one color argument, black in the pgm file stays black and white in the  pgm
       file  turns into the specified color in the ppm file.  Gray values in between are linearly
       mapped to differing intensities of the specified color.

       If you specify two color arguments (separated by a dash), then black gets  mapped  to  the
       first color and white gets mapped to the second and gray values in between get mapped lin-
       early (across a three dimensional space) to colors in between.

       You can specify the color in one of five ways:

       o      A name, from an X11-style color names file.

       o      An X11-style hexadecimal specifier: rgb:r/g/b, where r g	and  b	are  each  1-  to
	      4-digit hexadecimal numbers.

       o      An X11-style decimal specifier: rgbi:r/g/b, where r g and b are floating point num-
	      bers between 0 and 1.

       o      For backwards compatibility, an old-X11-style hexadecimal  number:  #rgb,  #rrggbb,
	      #rrrgggbbb, or #rrrrggggbbbb.

       o      For backwards compatibility, a triplet of numbers separated by commas: r,g,b, where
	      r g and b are floating point numbers between 0 and 1.  (This style was added before
	      MIT came up with the similar rgbi style.)

       Also,  you can specify an entire colormap with the -map option.	The mapfile is just a ppm
       file; it can be any shape, all that matters is the colors in it and their order.  In  this
       case, black gets mapped into the first color in the map file, and white gets mapped to the
       last and gray values in between are  mapped  linearly  onto  the  sequence  of  colors  in

       The  "maxval,"  or depth, of the output image is the same as that of the input image.  The
       maxval affects the color resolution, which may cause quantization errors you don't antici-
       pate in your output.  For example, you have a simple black and white image (in fact, let's
       say it's a PBM file, since pgmtoppm, like all Netpbm programs, can accept a PBM file as if
       it  were  PGM.	The  maxval  of this image is 1, because only two gray values are needed:
       black and white.  Run this image through pgmtoppm 0f/00/00 to try to make the image  black
       and  faint  red.  Because the output image will also have maxval 1, there is no such thing
       as faint red.  It has to be either full-on  red	or  black.   pgmtoppm  rounds  the  color
       0f/00/00 down to black, and you get an output image that is nothing but black.

       The fix is easy:  Pass the input through pnmdepth on the way into pgmtoppm to increase its
       depth to something that would give you the resolution you need to get your desired  color.
       In  this  case,	pnmdepth  16 would do it.  Or spare yourself the unnecessary thinking and
       just say pnmdepth 255 .

       pnmdepth(1), rgb3toppm(1), ppmtopgm(1), ppmtorgb3(1), ppm(5), pgm(5)

       Copyright (C) 1991 by Jef Poskanzer.

					 24 January 2001			      pgmtoppm(1)

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