Originally Posted by stewacide
So you're saying the Kobo's so sub-optimal greyscale conversion / it's better to upload covers / images already converted to greyscale my Calibre?
Hmmm... suboptimal? Quite likely. It takes quite a few CPU cycles to dither the image. Since I seldom spend much time looking at the cover images, it doesn't bother me. On a few occasions, I have taken colour illustrations in a book and converted them to what I consider to be a better format.
As for Calibre's conversion, I've never used it so not sure as to whether it dithers images or if it dithers them, what algorithm it uses for the dithering. Gives me something to play with this weekend.