I did a bit more research on djvu, and have done some more experiments. Long ago, I rescued a huge number of old Scientific American magazines from the dumpster of our local library. I grew up reading the Amateur Scientist column conducted by C. L. Stong, and of course Martin Gardner’s superb Mathematical Games. I ended up redonating most of those magazines to another library (who probably prompty threw them out).

Nevertheless, I do still have a few that include topics of interest, and decided to use one of them as source material for my experiments. In November 1981, the topic was pinhole cameras. I disassembled my copy of Scientific American and fed it to my $50 scanner, generating six 25 megabyte scans. I then converted these to reasonable quality JPEG images, and uploaded them to the
Any2DJVU service that is available on djvuzone. I took the individual pages and downloaded them, and using the djvm program, assembled them into a single downloadable document, which you can see here.

The resulting compression is 550:1. Not too shabby.

This compression seems to be hard to achieve using purely free tools on my machine. In particular, the free tools don’t include a tool for performing the segmentation that makes the overall process tractable. I’ve been toying around with crudely doing the segmentation by hand, but the results aren’t as good as the automatic version.

Anyway, I may convert some other of my available documents into this format
for redistribution, including some hard to find and useful telescope information.
Stay tuned.