Xerox scanners and photocopiers randomly alter numbers in scanned documents

This class of error is called (by me, at least) a "contoot" because, long ago, when I was writing the JBIG2 compressor for Google Books PDFs, the first example was on the contents page of book. The title, "Contents", was set in very heavy type which happened to be an unexpected edge case in the classifier and it matched the "o" with the "e" and "n" and output "Contoots". The classifier was adjusted and these errors mostly went away. It…

> This is not an OCR problem (as we switched off OCR on purpose), it is a lot worse – patches of the pixel data are randomly replaced in a very subtle and dangerous way: The scanned images look correct at first glance, even though numbers may actually be incorrect. I have a habit of scanning invoices/statements/manuals etc to pdf and found the above quite alarming. Though I don't use Xerox (my scanner is Epson Perfection V39), I never considered…

This is relatively new: > March 2015: The German Federal Office for Safety in Information Technology bans JBIG2 from being used for archival purposes.

Looks like a poorly implemented compression algorithm, or something. It's scary to think what this could cause, though.