Kindle and print have different requirements.
For print, you need as high quality as possible.
For kindle as low quality as possible without losing anything.
I found line based maps had to be in high quality BMP or they simply went fuzzy on the device.
But normal photo like images, the jpg can be reduced down in quality dramatically, so the file size is a small as possible, without losing anything on the device.
In Photoshop for example, when saving a jpg, you can reduce the quality slider right down to 2 or 3, and not lose a viable image on a device.
But if you do that for the print version, you very definitively lose viability. (Just proved that with a book I'm working on at the moment, with lots of both maps and photos. I had to redo the print version completely with high res images, just to make sure they printed well enough, as the first proof was quite disappointing.