psblack man page
psblack — PostScript filter.
psblack < input_PostScript_file > output_PostScript_file
psblack is a filter which reads a PostScript file as input and writes a PostScript file as output. In the output file the filter forces a black background and scales the intensity values (values with R=G=B) so that any intensity greater than or equal to .8 is mapped to white. This filter works only on PostScript files produced by ctrans - the CGM translator in the NCAR Graphics software.
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University Corporation for Atmospheric Research
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