ppmtopgm

 

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 ppmtopgm(1)                                           ppmtopgm(1)
 
 
 
NAME
        ppmtopgm  -  convert  a  portable  pixmap  into a portable
        graymap
 
SYNOPSIS
        ppmtopgm [ppmfile]
 
DESCRIPTION
        Reads a portable pixmap as  input.   Produces  a  portable
        graymap as output.  The output is a "black and white" ren­
        dering of the original image, as in a black and white pho­
        tograph.  The quantization formula used is .299 r + .587 g
        + .114 b.
 
        Note that although there is a pgmtoppm program, it is  not
        necessary for simple conversions from pgm to ppm , because
        any ppm program can read pgm (and pbm  )  files  automati­
        cally.   pgmtoppm is for colorizing a pgm file.  Also, see
        ppmtorgb3 for a different way of converting color to gray.
        And  ppmdist  generates  a  grayscale  image  from a color
        image, but in a way that makes it  easy  to  differentiate
        the original colors, not necessarily a way that looks like
        a black and white photograph.
 
 
 QUOTE
        Cold-hearted orb that rules the night
        Removes the colors from our sight
        Red is gray, and yellow white
        But we decide which is right
        And which is a quantization error.
 
SEE ALSO
        pgmtoppm(1),ppm­
        torgb3(1),rgb3toppm(1),ppmdist(1),ppm(5),pgm(5)
 
AUTHOR
        Copyright (C) 1989 by Jef Poskanzer.
 
 
 
                           10 April 2000               ppmtopgm(1)

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