Originally Posted by SBT
I've fiddled a bit with b&w print illustrations in ebooks; I like to get the background white instead of the light grey that the original scans normally have. I use Imagemagick, so I can do batch operations on all images at once, get fairly decent results. If you run the images through
convert file.png -level 20%,85% new-file.png
you get a white background and clearer black lines. You can also sharpen the images a bit, if you like:
convert file.png -level 20%,85% -unsharp 0.7x0.7+3+0 new-file.png
(That's the parameters I found worked for the images in this book)
Thanks, SBT. That's an interesting suggestion. I'll have a look at Imagemagick.