First, to whomever undeleted this thread, thank you!
Originally Posted by PeterT
strong probability that compressing them again will actually cause the files to grow in size
Negative. All compression algorithms have a "if compression expands then store" feature.
Yes, that some formats are already compressed was the whole point. I was just curious how efficient they are at storing text. To know the answer I *had* to remove the images, because otherwise I was also measuring a separate variable: image compression, which can be adjusted all over the place and wasn't what I wanted to measure. BTW the command I gave was wrong. PM me if you want to do this test yourself. (One needs */*.jpg etc also.)
I completely agree it is morally wrong to remove images. In my case I wanted to measure something. I should probably be burned at a stake for doing that. But, OTOH, I once read about an sf author who was very upset about the picture the publisher had drawn for his book. It was against the meme of the book. You know how they try to sex up stuff these days. The author lost out. Also, my reader creates a library some mystery place on the hdd, and was going super slow. And HDD was out of disk space. My hdd is always low on space. I blamed a recipe book with like 100 hd images. Can clog up your computer & your reader.