xwdtopnm
Convert an X11 or X10 window dump file to PNM. tldr-pages
On several platforms
Several platforms
Convert an XWD image file to PBM
xwdtopnm path/to/input_file.xwd >path/to/output_file.pnmIdentifyDisplay information about the conversion process
xwdtopnm -verbose path/to/input_file.xwd >path/to/output_file.pnmIdentifyDisplay the contents of the X11 header of the input file
xwdtopnm -headerdump path/to/input_file.xwd >path/to/output_file.pnmIdentify