David Kriesel: Lies, damned lies and scans
Why Hacker News recommends it
The standard reference whenever HN discusses the Xerox scanner bug or AI and compression that fabricates content.
What it is
David Kriesel's FrOSCon talk on how Xerox scancopiers, due to JBIG2 compression, silently replaced digits in scanned documents. He walks through how he discovered the bug and why it is so dangerous.
Recommended by 2 HN commenters across 2 different months, 2020 to 2026.
What Hacker News said
Recommends bXVsbGVy · 2020-08 · on “PDF: Still unfit for human consumption, 20 years later”
> You may remember that this played a strange role in Obama's birth certificate some years back Just to clarify, the issue with the compression algorithm used by the scanner, not with the PDF format itself. There a few videos of David Kriesel explaining the bug for the curious: [this video]
Recommends lynx23 · 2023-06 · on “”
Even though this happened a long time ago, whenever I hear or think about it, I am a mazed that it didn't put Xerox out of business, or at least hurt a little more. After all, some big players were already doing digital archiving at the time. :-/ BTW, the CCC had a pretty neat presentation at that time as well: [this video]
Cites dorgo · 2021-03 · on “Adobe Photoshop's 'super resolution' made my jaw hit the floor”
Sounds like the next iteration of "Lies, damned lies and scans": [this video] >On the scale of things too horrible to contemplate, "document-altering scanner" is right up there with "flesh-eating bacteria". Since 2006, Xerox scancopiers literally are making stuff up. They, for example, replace digits with others in scans.
Cites maxnoe · 2021-11 · on “Confused Xerox copiers rewrite scanned documents, expert finds (2013)”
There is a version with an English voice over of the original talk here: [LINK] And the talk he gave in English himself here: [this video]
Cites Terr_ · 2026-03 · on “OCR For construction documents does not work, we fixed it”
> OCR for construction documents does not work I'm reminded of the Xerox JBIG2 bug back in ~2013, where certain scan settings could silently replace numbers inside documents, and bad construction-plans were one of the cases that led to it being discovered. [0] It wasn't overt OCR per se , users weren't trying to convert pixels to characters. [0] [this video]