Top all-time · #495
David Kriesel
Personal blog · dkriesel.comaiscienceprogramming
David Kriesel writes D. Kriesel, a personal blog at dkriesel.com about ai, science and programming. Since 2013, 118 different Hacker News readers have linked it 133 times, most often “Xerox scanners/photocopiers randomly alter numbers in scanned documents (2013)”. It is still writing: the last post was on 2026-08-25, and you can follow it by feed.
Rarely recommended · 0 of 40 sampled comments recommend it?
Why HN links it
HN readers link his 2013 post on Xerox scanners silently changing digits whenever lossy compression, OCR or AI image errors come up, as a reference example.
Summarised by Claude from a sample of 40 HN comments that link here. Each comment is marked recommending, critical or neutral (citing without judging); how this works.
News
Most-linked posts?
- Xerox scanners/photocopiers randomly alter numbers in scanned documents (2013)52 people · 58 mentions · first linked 2013-08-02
- Xerox scanners/photocopiers randomly alter numbers in scanned documents (2013)47 people · 51 mentions · first linked 2021-03-13
- A Brief Introduction to Neural Networks2 people · 2 mentions · first linked 2014-05-26
- /en/blog/2013/0802_xerox-workcentres_are_switching_written_numbers_when_scanning2 people · 2 mentions · first linked 2025-12-15
- A Brief Introduction to Neural Networks [pdf]2 people · 2 mentions · first linked 2016-08-06
- A data-driven guide to creating successful HN posts (HN is similar to Reddit)2 people · 2 mentions · first linked 2015-10-25
What Hacker News says?
What could possibly go wrong? https://www.dkriesel.com/en/blog/2013/0802_xerox-workcentres...
Comment linking /en/blog/2013/0802_xerox-workcentres_are_switching_written_numbers_when_scanning
on “I started a paper website business”Submitted Xerox scanners and photocopiers randomly alter numbers in scanned documents as a story · 570 points
HN discussionSo… when are we going to see made up numbers in photographed documents again? https://www.dkriesel.com/en/blog/2013/0802_xerox-workcentres... Superimposing other's people face onto a photo from a crime scene? Or, as part of my work, I photograph electric switchboards for documentation and diagnostic purposes. Hopefully I won't get any hallucinated connections, right?
Comment linking /en/blog/2013/0802_xerox-workcentres_are_switching_written_numbers_when_scanning
on “iPhone camera app replaces person’s head with a leaf in photo”Submitted Xerox scanners/photocopiers randomly alter numbers in scanned documents (2013) as a story · 486 points
HN discussionReminded me of the infamous Xerox copier bug that changed numbers in copies! https://www.dkriesel.com/en/blog/2013/0802_xerox-workcentres...
Comment linking /en/blog/2013/0802_xerox-workcentres_are_switching_written_numbers_when_scanning
on “iPhone camera app replaces person’s head with a leaf in photo”- jf · 2015-05-21
Submitted Xerox scanners/photocopiers randomly alter numbers in scanned documents (2013) as a story · 159 points
HN discussion Thanks for the complementary links! Regarding Xerox scanner compression issues, compare this great CCC-talk by David Kriesel, "Traue keinem Scan, den du nicht selbst gefälscht hast" [0] – Sorry, German only. [0] https://www.youtube.com/watch?v=7FeqF1-Z1g0 [1] http://www.dkriesel.com/en/blog/2013/0802_xerox-workcentres_... (Didn't MS's PDF-viewer have similar issues?)
Comment linking /en/blog/2013/0802_xerox-workcentres_are_switching_written_numbers_when_scanning
on “DARPA Is Building a $10M, Open-Source, Secure Voting System”Submitted A data-driven guide to creating successful HN posts (HN is similar to Reddit) as a story · 48 points
HN discussionXerox copiers had a bug caused by a failed image (re)construction, which caused it to replace similar (but not identical) parts of an image with other pieces of the image. http://www.dkriesel.com/en/blog/2013/0802_xerox-workcentres_... ?
Comment linking /en/blog/2013/0802_xerox-workcentres_are_switching_written_numbers_when_scanning
on “Learning to See in the Dark (2018)”Submitted Xerox scanners/photocopiers randomly alter numbers (no OCR involved) as a story · 34 points
HN discussionHere is the link to the blogpost that describes the problem: http://www.dkriesel.com/en/blog/2013/0802_xerox-workcentres_... ?
Comment linking /en/blog/2013/0802_xerox-workcentres_are_switching_written_numbers_when_scanning
on “Compressing and enhancing hand-written notes (2016)”Submitted Distributed Evolution of Swarms (2009) as a story · 12 points
HN discussionIf you then destroy the physical copy, how can you validate if the digitalisation succeeded? For example, many Xerox scanners "switch" numbers when scanning: https://www.dkriesel.com/en/blog/2013/0802_xerox-workcentres... Those who used them to digitize, e.g, accounting documents, and then destroyed the originals, are proper screwed.
Comment linking /en/blog/2013/0802_xerox-workcentres_are_switching_written_numbers_when_scanning
on “€2.6M spent for a book at auction, believed they would own the IP”Submitted Xerox scanners/photocopiers randomly alter numbers in scanned documents (2013) as a story · 3 points
HN discussionre edit: No, that's just a terrible idea. It might work quite well in the sense that it prevents server security holes. But it makes for terrible usability, and potentially even security problems for the user. The user expects that their input is reproduced correctly, and if it isn't, that can potentially have catastrophic consequences because it might result in silent corruption. See also: http://www.dkriesel.com/e…
Comment linking /en/blog/2013/0802_xerox-workcentres_are_switching_written_numbers_when_scanning
on “The Correct Way to Validate Email Addresses”Submitted Xerox scanners/photocopiers randomly alter numbers in scanned documents as a story · 3 points
HN discussionI can totally see Google incorporating this in Self driving cars down the road, after training on millions of hours or dashcam footage, to augment or maybe even replace Lidar. Paper suggests it is capable of segmenting 2D picture input into logical objects and their discrete configurations/positions. Its not without its pitfalls tho, instead of Monocular SLAM generating factual, albeit fuzzy point cloud map we get o…
Comment linking /en/blog/2013/0802_xerox-workcentres_are_switching_written_numbers_when_scanning
on “Neural scene representation and rendering”Submitted Xerox scanners/photocopiers randomly alter numbers in scanned documents (2013) as a story · 2 points
HN discussion> incorrect detail generation Absolutely. Reminds me of Xerox number mangling: https://www.dkriesel.com/en/blog/2013/0802_xerox-workcentres...
Comment linking /en/blog/2013/0802_xerox-workcentres_are_switching_written_numbers_when_scanning
on “Show HN: I turned my face rec system into a video codec”Submitted Xerox scanners/photocopiers randomly alter numbers in scanned documents (2013) as a story · 2 points
HN discussionIt was Xerox. http://www.dkriesel.com/en/blog/2013/0802_xerox-workcentres_...
Comment linking /en/blog/2013/0802_xerox-workcentres_are_switching_written_numbers_when_scanning
on “Stealth Cell Tower Disguised as Printer”Submitted A Brief Introduction to Neural Networks as a story · 2 points
HN discussionLossy compression does make things up. We call them compression artefacts. In compressed audio these can be things like clicks and boings and echoes and pre-echoes. In compressed images they can be ripply effects near edges, banding in smoothly varying regions, but there are also things like https://www.dkriesel.com/en/blog/2013/0802_xerox-workcentres... where one digit is replaced with a nice clean version of a dif…
Comment linking /en/blog/2013/0802_xerox-workcentres_are_switching_written_numbers_when_scanning
on “An LLM is a lossy encyclopedia”Submitted A data-driven guide to creating successful Hacker News posts(2015) as a story · 2 points
HN discussion> and connected them realistically… Well, that's the crux of the issue that you don't seem to see. For many observers, it does not look realistic . The unnaturalness of the pixels is what makes it plausible for Apple software to have a bug. If it looked 100% realistic to everyone, we wouldn't be in this thread discussing it. E.g. Image saving algorithm with a software bug can cause pixels to be incorrectly "replaced…
Comment linking /en/blog/2013/0802_xerox-workcentres_are_switching_written_numbers_when_scanning
on “Update: iPhone Camera app did not replace person's head with a leaf”Submitted Xerox scanners/photocopiers randomly alter numbers in scanned documents as a story · 2 points
HN discussion> I'm sure this type of thing degrades bayesian priors for everyone reading it What kind of thing do you mean by "this type of thing"? Why do you think it degrades bayesian priors? Life is, among other things, a constant quest to better understand the world around us. For every "real discovery" there is a ton of noise. Most of that noise can be easily discarded, some look more convincing. This particular instance lo…
Comment linking /en/blog/2013/0802_xerox-workcentres_are_switching_written_numbers_when_scanning
on “Update: iPhone Camera app did not replace person's head with a leaf”Submitted A Brief Introduction to Neural Networks [pdf] as a story · 2 points
HN discussionHere's a similar case of a scanner using a traditional compression algorithm. It has a bug in the compression algorithm, which made it replace a number in the scanned image with a different number. https://www.dkriesel.com/en/blog/2013/0802_xerox-workcentres...
Comment linking /en/blog/2013/0802_xerox-workcentres_are_switching_written_numbers_when_scanning
on “Stable Diffusion based image compression”Submitted Xerox scanners/photocopiers randomly alter numbers in scanned documents (2013) as a story · 1 points
HN discussion
