XWD

Overview
XWD (X Window Dump) is a raster image file format used by X-Windows.

There are two versions of it: X10 and X11. They have different header formats and capabilities.

There is no official specification, and it is challenging to decode all the possible types of XWD images.

Some sources list .xdm as an alternate file extension, but others imply that xdm files have a different format.

Software

 * Netpbm
 * XnView

Sample files

 * http://www.fileformat.info/format/xwd/sample/index.htm

Resources

 * XWD File Format Summary
 * MultimediaWiki article