I was always interested in glitching images - but was frustrated with the checksum/read errors. I took a slightly different approach with JPGCrunk (http://www.mrspeaker.net/dev/jpgcrunk/): instead of modifying the image then trying to display it, randomly mess with the internals of the encoder (I used a JavaScript implementation so it was easy to modify https://github.com/mrspeaker/jpgcrunk/blob/master/scripts/en...)

This way the "glitching" happens inside the encoder algorithm, and then there's nothing to have to repair!