I put the four Sitepoint PDFS I own* onto a Kindle I borrowed. The text looks great, but most of the pictures look really bad. They often have recognizable elements to them, but then there are lines or boxes all over them. Most of them are screenshots; for some reason the ones taken on OS X seem to be trouble-free

I know Sitepoint offers mobi books now; I'm trying to get ahold of my order numbers so I can download those. But I wonder, is this image corruption just a problem with Kindle's PDF reader, or is something in Sitepoint's PDF creation process to blame?

* The books where I've seen the problem:
- Build your own web site
- Build your own database-driven web site
- Simply Javascript
- Jquery: novice to ninja