from Hacker News

How to Store Data on Paper?

by mofosyne on 5/31/25, 7:20 AM with 77 comments

• by pastage on 6/3/25, 8:19 AM

  Bits per [cm²|cm³|kg] is interesting like you get with cuneiform ceramic tablets[1], this one get about 1 word per cm² and cuneiform is crazy dense, I have no real grasp of how sumerian or akkadian words worked. I think it was heavily context based because from some lecture[2] at the British Museum.

  I have seen people do ceramics where information was stacked in layers and had to be destroyed to extract. The ultimate form of shifting media to preserve and read information. I guess that could done with better resolution with 3D printed Zirconia (0.1 mm³ blobs) so 1Mb /cm³

  Edit: this idea of a cold storage is from Footfall by Niven and Pournelle, where information was stored on monoliths where layers could be incrementally extracted with tools documented on the above layers. i.e. start with 0.1 bit per m² and go down, done with the hand wavy handling of practical problems in science fiction.

  [1] https://www.bookandsword.com/2016/10/29/the-information-dens...

  [2] https://youtu.be/XVmsfL5LG90

• by tocs3 on 5/31/25, 1:51 PM

  I have been thinking about this for a long time. Thanks for the link.

  The biggest advantage of character-based encodings is that they can be decoded by humans (as opposed to dot-based encodings), which means that you don’t need a camera or a scanner to recover the data.

  This is an interesting point. In our post apocalyptic future scholars will be using their quills to translate archives of these (in my imagination anyway). Of course they would have to translate into binary and then into human chars.

  I can imaging they will be sad they cannot listen to the mp3's.

  Adding color allows on to code more information per dot (3x more with three colors).

  Is this right? Wouldn't it be base-3 encoding? Three bits of binary can count to 8. Three trits of base three can count to 27. Color has all sorts of disadvantages but maybe a much greater payoff (unless I m mistaken).

• by benhurmarcel on 6/3/25, 12:53 PM

  I have this type of issue professionally too, even though we don't use paper. For regulatory reasons, the only approved format we are allowed to use for long term archiving is PDF/A. No attachments, only pages in a single PDF document.

  It has shown to be an issue for including data, or spreadsheets. Most colleagues just print Excel files to a PDF that gets appended, but while it complies with the regulation it's basically unusable as-is.

• by rickcarlino on 6/3/25, 3:50 AM

  I got curious about OCR as a sort of poor man’s microfiche. I printed a test paragraph on high quality paper with a laser printer. The smallest font I could read under a USB microscope was 2.5pt, though I could probably have gone smaller if I used polymer paper. The fibers of the paper are quite apparent under a microscope. Transparency film paper was too smudgy.

• by lifthrasiir on 6/3/25, 8:38 AM

  I pondered this from time to time and concluded that paper data storage is of very limited use, mainly because of the information density. Any remotely human-readable form is too sprase to be useful (<10 KB/page), while dot-based or color-based approaches are heavily limited by printing techniques (<500 KB/page). It is hard to preserve paper, unless you are willing to sacrifice its information density even more.

  For this reason, paper is at best useful as a bootstrapping mechanism, which would allow readers to construct a mechanism to read more densely encoded data. My best guess is that the main storage of information in this case would likely be microfilms, which should be at least 100x dense than the ideal paper data storage. Higher density allows for using less dense encodings to aid readers. And as far as I know microfilms are no harder to preserve than papers.

• by account-5 on 6/3/25, 8:07 AM

  Color Dot Encodings is interesting, you could encode data in a floor mozaic. And with my limited understanding the more colours the high the amount of data?

  You could encode data in monolithic structures this way. They'd last longer than paper and given future generations lots of confusion trying to figure out the meaning.

• by 6510 on 6/3/25, 1:01 PM

  I haven't build it because it costs a bit to much for my budget but someone some day should build the megalithic computer according to my vision: We take a river flowing down a mountain in a suitable location and carve out square canals. The AND gate is done by having a giant door attached to two blocks hollowed out from the bottom. If both blocks are submerged in water together they lift the door and water may flow into the rest of the circuitry. A grid of basins functions as the display and to store values. The input is done by putting weights onto the floating blocks thereby preventing them from lifting specific doors. I doubt it can be made large enough to run doom but it doesn't hurt to be ambitious.

• by ryukoposting on 6/3/25, 11:49 AM

  Fun fact: magazines actually distributed software on paper briefly in the 1980s.

  https://youtu.be/mIGotStRCkA?si=toG5xeLMZzjIGTxC

  It's more like a long, linear barcode, but still. More often, they put the source code in the magazine and you'd just type it into your machine.

• by mk_stjames on 6/3/25, 7:48 PM

  70-100 kilobytes on a single sheet of paper by tiling QR codes is pretty dense.

  I find it interesting that, if you were print 4 sheets double sided you would have roughly the same amount of information stored as a 720kb 5 1/4" floppy disk and if you cut and folded it would take up roughly the same size and weight.

• by bn-l on 6/3/25, 11:35 AM

  I did my own testing of this. I arrived at using very large QR codes with a lot of redundancy. You can scratch them etc and they’ll still read. Also it’s an extremely ubiquitous format and everyone knows what it is by looking at it.

• by zvr on 6/3/25, 8:30 AM

  Interesting.

  I am not sure why, for character-based encodings, they used a general-purpose font (Inconsolata) rather than one that is specifically made for OCR -- and how this would have made it better.

  Going further, if you only print a limited alphabet (16, 32 or 39 symbols) why not use a specialized font with only these characters? The final step is to use a bitmap "font" that simply shows different character values as different bit patterns.

• by pmontra on 6/3/25, 7:26 AM

  The post is 504 now. Alternative link: http://archive.today/N9ZTb

• by calrain on 6/3/25, 8:10 AM

  First, encode data as an image. Second, work out the best image for printing/scanning purposes.

  I saw some work a while ago of storing SQL extracted table data as an image, and always thought that with good compression and a good printer, you could make paper copies.

• by talles on 6/3/25, 4:27 PM

  I'm imagining that for most of the examples you have to own a printer/scanner with better than average resolution and that the paper would only work if in pristine condition, considering how small the visual details are.

• by eimrine on 5/31/25, 7:40 AM

  Thank you for sharing! I would like to get deeper: how many Bytes is possible to write on a paper with this or that encoding, how about having some extra bits for the sake of data loss recovery, what are approaches to a multi-page storages and are there any patches for incremental archiving?

  I will try to remove dust from my A4 scanner and try to read that MP3 from printed medium, seems a bit insane to store multimedia in a paper but who needs to store it without proven ability to read. My printers love to mess with ink (especially ones with pirate-refilled cartridge) so I do not really believe this is practically at maximum resolution.

• by Hyperlisk on 6/3/25, 2:37 PM

  Here is some related software from many years back: https://ollydbg.de/Paperbak/index.html

• by c0nsumer on 6/3/25, 6:47 PM

  This reminds me of PaperDisk: https://www.paperdisk.com/id1.html

• by bob1029 on 6/3/25, 7:14 AM

  Something like PDF417 would be what I reach for if I needed a very robust physical representation.

  I've seen these barcodes scan accurately off dingy plastic cards using webcams.

  The information level per symbol is not great (about 1kb), but the error correction and physical layout work really well.

• by mihaigalos on 6/3/25, 1:59 PM

  Excellent article. Cimbar codes can encode glyphs yielding about 10 kB/qrcode, stackable. Ref: https://github.com/sz3/cimbar

• by makeworld on 6/3/25, 4:15 AM

  I wonder if you could add error correction to get around OCR failures.

• by slaymaker1907 on 6/3/25, 7:26 PM

  I'd always wondered how much data you can store on paper using QR codes given that print media seems to be much better at surviving for long periods of time.

• by blueboo on 6/3/25, 9:43 AM

  I would’ve thought the interesting angle here is about leveraging 1) the 2d space of the page and 2) color in service of compressive encoding.

• by kragen on 6/3/25, 12:21 PM

  Acid-free paper has a lot to recommend it: an archival lifespan of about 1000 years, low cost, and widespread equipment for printing it en masse very cheaply. Other media are superior in one or another way, but all are far more expensive.

  It's probably worth mentioning https://github.com/za3k/qr-backup/ which is tested in practice rather than merely theoretical. It doesn't achieve very high density, though.

  The theoretical information capacity of an uncoated 600dpi laser-printed page ought to be close to 600×600 bits per square inch, 23.6×23.6 bits per square millimeter in modern units. This is 33.7 megabits per US letter page or 34.8 megabits per A4 page. The bit error rate of a laser printer is quite low, under 1%, and the margins are maybe another 5% at most. So modest ECC ought to be able to deliver most of that channel capacity in practice. QR codes and OCR apparently don't come close.

  As an exercise, 13 years ago, I designed a proportional 1-bit-deep pixel font for printable ASCII, based on Janne Kujala's work, that averages about 3½×6 pixels. This is about 20 bits per character, so a letter-sized page should hold almost a megabyte of human-readable ASCII text. I generated the King James Bible in it at 600dpi. It comes to about four pages. Printed out in a half-assed way at double size (300dpi) on a 600dpi printer, you can read it pretty easily with a good magnifying glass. I have not yet been able to get an even partly readable printout at full resolution. If someone else tries it, I'm interested in hearing your results.

  http://canonical.org/~kragen/bible-columns.png (warning, 93+-megapixel image, 4866×19254)

  http://canonical.org/~kragen/bible-columns-320x200.png (small excerpt from the above)

  http://canonical.org/~kragen/sw/netbook-misc-devel/6-pixel-1... (the font as a 374×7 image)

  http://canonical.org/~kragen/sw/netbook-misc-devel/propfontr... (the image generation program I regret having written in Python because it won't run in current Python)

  http://canonical.org/~kragen/sw/netbook-misc-devel/bible-pg1... (test input text, public domain everywhere except the UK)

• by KWxIUElW8Xt0tD9 on 6/3/25, 11:00 AM

  There was once work on metalized optical paper tape of very high density for archival purposes -- what happened to that?

• by superpupervlad on 6/3/25, 4:46 PM

  Looking at the title I thought this articles going to be about organising personal notes in notebook

• by vubecnevim on 6/3/25, 7:11 AM

  And now imagine you could save not just text or images or music but also more abstract things like emotions and meaning. And now imagine you can do it in a true human readable form so that many people (not just scholars or priest with secret knowledge) in a post apocalyptic or indeed a normal future can read it. And now imagine that only a limited set of characters even very simple ones can store that data even in just one character measuring just enough space so one can read it. How awesome is that? And we already have this system and it was developed thousads of years ago.

• by slowhadoken on 6/3/25, 5:22 PM

  I vote we go back to punch cards.

• by welder on 6/3/25, 12:23 PM

  If you want the data to last a long time, make sure to print on acid free paper.

• by tiahura on 6/3/25, 1:12 PM

  Do any programmers still print reams of green bar paper to review their code?

• by pknerd on 6/3/25, 4:26 PM

  But how to decode it back?

• by pknerd on 6/3/25, 4:26 PM

  But how to decode it back?

• by dsign on 6/3/25, 8:11 PM

  How long before anybody uses this to create those pieces of paper that glue the covers in a hardcover to the paper block? Just saying, with the advent of LLMs, handcrafted paper books may become all the rage again.

• by drsopp on 6/3/25, 6:05 AM

  (2020)