Provided by: netpbm_10.0-15.3build1_amd64
xwdtopnm - convert a X11 or X10 window dump file into a portable anymap
Reads a X11 or X10 window dump file 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. The program tells you which type it is writing. Using this program, you can convert anything on an X workstation's screen into an anymap. Just display whatever you're interested in, do an xwd, run it through xwdtopnm, and then use pnmcut to select the part you want.
I haven't tested this tool with very many configurations, so there are probably bugs. Please let me know if you find any.
Copyright (C) 1989, 1991 by Jef Poskanzer. 11 January 1991 xwdtopnm(1)