• On a LINUX machine, I ran xdoom, the shareware X-Windows version of DOOM, the game by id Software
• xwininfo (a standard X11 utility) returned the X window ID of the DOOM window, for use with xwd, another standard X11 utility that dumps window images
• A GNU bash shell loop like this began a series of window dumps:

  i=0
  while true; do
  	xwd -id WINID -out $i.xwd
  	i=$[$i+1]
  done
  

• I fired the rocket launcher in the DOOM window, then stopped the shell loop
• Using xwud (X Window UnDump - the inverse of xwd), I previewed the captured window dumps until I found one I liked - 34.xwd
• I used ImageMagik to convert the X Window Dump into a MIFF (ImageMagik interchange format), and then into a GIF - 34.gif
  

• The most time consuming step was using XPaint to replace the background with solid cyan, creating 34overlay.gif
  

• ImageMagik was used again to build another MIFF, this time specifying -transparent #00ffff to make the cyan transparent

• I downloaded Z186-207.mpg, a clip from the Zapruder film, from ??
• ImageMagik (compiled with the MPEG option, using the UCB/MNI MPEG library) broke the MPEG into a set of MIFFs
• I selected the third MPEG frame, Zapruder frame 188 - Z188.gif
  

• The ImageMagik combine utility was used, with the -compose over option to overlay the images. A -geometry switch was also needed for correct alignment
• ImageMagik converted the resulting MIFF to final GIF, using -interlace none to prevent progressive loading, which might ruin the surprise...

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