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

pngtopnm(1)			     General Commands Manual			      pngtopnm(1)

       pngtopnm - convert a Portable Network Graphics file into a portable anymap

       pngtopnm [-verbose] [-alpha | -mix] [-background color]
       [-gamma value] [-text file] [-time] [pngfile]

       Reads  a  Portable  Network Graphics as input.  Produces a portable anymap as output.  The
       type of the output file depends on the input file - if it's black & white, a pbm  file  is
       written, else if it's grayscale a pgm file, else a ppm file.

	      Display the format of the input file and the type of the output file. If the chunks
	      are part of the png-file, the alpha, transparency and gamma-values  will	be  indi-

       -alpha Output  the alpha channel or transparency mask of the image. The result is either a
	      pbm file or pgm file, depending on whether different levels of transparency appear.

       -mix   Compose the image with the transparency or alpha mask  against  a  the  background.
	      When a background chunk is available that color is taken, else black will do.

       -background color
	      If  no background color chunck is present in the png-file, or when another color is
	      required this parameter can be used to set the background color of images. This  is
	      especially  useful  for alpha-channel images or those with transparency chunks. The
	      format, to specify the color in, is either (in the case of  orange)  "1.0,0.5,0.0",
	      where  the  values  are  floats  between	zero  and one, or with the syntax "#RGB",
	      "#RRGGBB" or "#RRRRGGGGBBBB" where R, G and B are hexa-decimal numbers.

       -gamma value
	      Converts the image to a new display-gamma value. When a gAMA chunk  is  present  in
	      the png-file, the image-gamma value will be used. When not, the image-gamma is con-
	      sidered to be 1.0. Based on the image-gamma and the display-gamma given  with  this
	      option the colors written to the pnm-file will be adjusted.
	      Because  the  gamma's of uncompensated monitors are around 2.6, which results in an
	      image-gamma of 0.45, some typical situations are: when the image-gamma is 0.45 (use
	      -verbose to check) and the picture is too light, your system is gamma-corrected, so
	      convert with "-gamma 1.0".  When no gAMA chunk is present  or  the  image-gamma  is
	      1.0, use 2.2 to make the picture lighter and 0.45 to make the picture darker.

       -text file
	      Writes the tEXt and zTXt chunks to a file, in a format as described in the pnmtopng
	      man-page.  These chunks contain text comments or annotations.

       -time  Prints the tIME chunk to stderr.

       All flags can be abbreviated to their shortest unique prefix.

       pnmtopng(1), ptot(1), pnmgamma(1), pnm(5)

       Instead of pngtopnm|pnmtoxxx, a specific converter should  be  used,  if  available.  E.g.
       ptot (PNG to TIFF conversion), etc.

       There  could be an option to read the comment text from pnm comments instead of a separate

       The program could be much faster, with a bit of code optimizing.

       Copyright (C) 1995-1997 by Alexander Lehmann
			       and Willem van Schaik.

					  6 January 1997			      pngtopnm(1)

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