pnmtorle - convert a Netpbm image file into an RLE image file.


pnmtorle [

-h ] [

-v ] [

-a ] [ -o outfile ] [ pnmfile ]


This program converts Netpbm image files into Utah

R RLE (5) image files. You can include an alpha mask. If the input is a multiple image file, the output consists of several concatenated RLE images.

The RLE file will contain either a three channel color image (24 bits) or a single channel grayscale image (8 bits) depending upon the pnm file depth. If a converted ppm is displayed on an 8 bit display, the image must be dithered. In order to produce a better looking image (on 8 bit displays), it is recommended that the image be quantizing (to 8 bit mapped color) prior to its display. This may be done by piping the output of this program into the Utah

R mcut (1) or

R rlequant (1) utilities. An example of this is shown later.



    This option will cause pnmtorle to operate in verbose mode. The header information is written to "stderr". Actually, there is not much header information stored in a Netpbm file, so this information is minimal.


    This option allows the header of the Netpbm image to be dumped to "stderr" without converting the file. It is equivalent to using the -v option except that no file conversion takes place.


    This option causes pnmtorle to include an alpha channel in the output image. The alpha channel is based on the image: Wherever a pixel is black, the corresponding alpha value is transparent. Everywhere else, the alpha value is fully opaque.

  • -o outfile
        If specified, the output will be written to this file. If outfile is "-", or if it is not specified, the output will be written to the standard output stream.
  • pnmfile
        The name of the Netpbm image data file to be converted. If not specified, standard input is assumed.


  • pnmtorle -v file.ppm -o file.rle
        While running in verbose mode, convert file.ppm to RLE format and store resulting data in file.rle.
  • pnmtorle -h file.pgm
        Dump the header information of the Netpbm file called file.pgm.


R rletopnm (1),

R urt (1),

R RLE (5).


Wes Barris
Army High Performance Computing Research Center (AHPCRC)
Minnesota Supercomputer Center, Inc.