工具与资源ollydbg.de
PaperBack——如何将数据存储在一张 A4/Letter 纸上
PaperBack – How to store data on a single A4/Letter sheet
2012 — 2024，它一次次回到首页
黑点是上首页（≥ 50 分）的那次投稿，空心点是没冲上去的投稿，点越大分数越高。
导读
PaperBack 是一个免费工具，可以把任意文件编码成打印在一张 A4 纸上的点阵图案，之后用扫描仪即可还原数据，并内置冗余机制以容忍纸张污损。页面介绍了其原理、容量和可靠性设置。
为什么经久不衰：用纸和扫描仪就能离线备份文件，这种极简、不依赖特定介质的存档思路在数字保存话题反复被提起，多年后依然引人入胜。
HN 评论精选
作者早在八十年代就实现过类似的纸面数据归档方案
这勾起了我的回忆。八十年代末我写过类似的程序，把一张 Apple II 软盘（140KB）归档到一张纸上。7×10 英寸的打印区域只需每平方英寸 2KB 的密度，约 128 DPI，勉强在我的点阵打印机能力范围内。当时我是青少年，不懂纠错码，就是简单的比特对像素映射。那时没有扫描仪，这是只写介质，但我还是用它归档了最重要的磁盘，想着几年后扫描技术会成熟。纸后来丢了，好在软盘本身撑到 1994 年，我用零调制解调器连接把它们传到了 PC 上。
apricot查看英文原文
This brings back memories. In the late eighties, I wrote a program similar to this one for archiving one Apple II floppy disk on a sheet of paper. One floppy disk is 140 kilobytes (35 tracks of 16 sectors containing 256 bytes each), so a sheet of paper with a 7-inch by 10-inch printed area needs a data density of just 2 kilobytes per square inch to fit a floppy disk, which comes out to a linear resolution of 128 dots per inch. This was (barely) within the specs of my dot matrix printer. I was a teenager at the time so I had no clue about error correcting codes and the like, it was a straight bit-to-pixel mapping. At the time, this was a write-only medium, as I did not have access to a scanner. No matter, I used it to archive my most important data disks, figuring that after a few years, technology would have improved enough to allow easy scanning. I eventually lost the sheets of paper, but the floppy disks themselves were robust enough to last until 1994, at which time I wrote a program to send them to my PC through a null-modem connection.
对比其他方案：彩色条码和微缩胶片容量更高、更实用
用微软的 HCCB 彩色条码，600dpi 彩色打印在 A4 上可达 1.5MB；再配合最好的压缩技术，可以把整部圣经、古兰经、摩诃婆罗多等大量典籍文本放进一张 A4。也可以存 4 分钟立体声音乐或半小时语音。不过更经济实惠的或许是微缩胶片——比如两英寸胶片上印整本圣经，不需要电脑，只需放大镜。
fsiefken查看英文原文
With HCCB (High Capacity Color Barcode) of which an implementation is Microsoft Tag you can get 1.5 MB with 600dpi color on a A4. If you add the best compression techniques (cmix v7) depending on the source material you could get 8 times as much english text, easily fitting the pearls or religion: Tenach, New Testament, Quran, Mahabarata, The Dhamapada, the Atthakavagga and the Parayanavagga, Rhinoceros and Lotus Sutra, The Book of the Dead and the Sri Guru Granth Sahib and explanatory texts and commentary on one single A4. Or you could get 4 minutes of stereo music, Opus@40Kbps or half an hour of speech Opus@6Kbps - (Vinyl LP seems to be more efficient and simpler for that). Or the best 25 classical pieces in MIDI, for example Beethoven Symphony #5 in C minor is a 322 KB midi file (compressed 60 KB). With compressed ABC or Alda notation you could even fit 10 times as much. Or you can just read the ABC and automatically 'hear' the music in your head (is there a similar notation for human movement or dance i wonder...). Even so perhaps a better and more cost effective system is microfilm, here an example of the bible printed on a 2 inch film: http://www.amazon.com/Microform-Bible-Much-Like-First/dp/B00FXHBBOO - you don't need a computer, just a lensing system. It has one downside, the blind cannot use this unless you'd make an OCR to TTS or braille display converter on top of it. Or as described in the book Mindhacker you could use Dutton Speedwords/Briefscript word abbreviations preferrable tailored to Esperanto to double the text on the microfilm or on your handwritten A4. https://github.com/leonardoce/bumot
指出 PaperBack 的冗余方案不如正规纠错码高效
PaperBack 用简单的冗余块分布来恢复损坏数据。请务必学习纠错码——大多数纠错码能以更少的开销提供好得多的纠错能力，可以看 Wolfram MathWorld 的文章，信息论教材里也大量涉及这个主题。
densh查看英文原文
> Redundancy helps to recover partially damaged data. Redundancy 1:5 means that for every 5 consecutive data blocks, if one block is completely unreadable, PaperBack will be able to restore it. To reduce damages caused by coffee pots and other common dangers, blocks are distributed around the page. Higher redundancy decreases page capacity but improves reliability. Please do study error correcting codes. Most of them can offer much better error correction with less overhead. Take a look at Wolfram's MathWorld article [1]. This topic is heavily covered in most information theory books. [1] http://mathworld.wolfram.com/Error-CorrectingCode.html
回忆八十年代杂志用条码分发源代码的类似技术
这让我想起 Cauzin Softstrip——当年杂志会印出源代码条码供人扫描录入。当然我买不起那么贵的扫描设备，只能忍受麻木的手打输入和随之而来的无数笔误。
pkaye查看英文原文
Reminds me of this https://en.wikipedia.org/wiki/Cauzin_Softstrip. Magazines would print out their source code and you could scan it in. Of course I had no money to buy such an expensive machine so was relegated to mind numbing typing and the inevitable typos that came with it.
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