How to Store Data on Paper?

Summary

How to print my voice? How to put music on paper? How to print an executable program? All this boils down to storing digital data on paper. This is also called paper data storage. Arrived in this domain from poetry, I’ve been investigating the area for some time. Here is what I found. What to print on paper? Printing an executable program (encoded in base64) Printing a secret message (encrypted with GPG-AES256, encoded as stacked qrcode). Printing a 21 seconds soundscape of a rugby match (in 64kpbs MP3 encoded with Optar) Printing a 7-page scientific paper on a single page (a PDF file encoded with colorsafe) How to transform digital data to a printable format? You need a format that transforms a sequence of bytes into an image with a specific encoding. Then, you need two pieces of software, one encoder (data->image) and one decoder (image->decoder). We now review different kinds of encodings. Character-based encodings TL;DR; OCR digital data is a very hard problem, one can get 2.5 kilobytes per A4 page that is decodable afterwards, see “How to get perfect OCR for digital data?”. With character-based encoding, the idea is to use a binary-to-text encoding and then to use optical character recognition (OCR). 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 the most robust assumption for extreme conditions. The information capacity primarily depends on the size of the alphabet and the font size (plus some variations due to the font being used). Yet, those numbers are theoretical in the sense that they assume perfect OCR. base16/hexadecimal: I can get 3.5 kilobytes per A4 page (font size 12pt, font Inconsolata) and OCR it with gocr at 400DPI. With smaller fonts, we have for example 4.6 kilobytes per A4 page (font size 9pt, font Inconsolata), but I cannot OCR it well (confusion between “7” and “1”), see “How to get...