While I'm ecstatic to see that you took my recommendation of using PNG for your greyscale sketches, I can't help but notice that they're really not all that well compressed at all - I mean, doing nothing but resaving >>22473 with PNG's standard built-in compression level set to only 1 (which is the lowest possible without counting uncompressed @ level 0) actually still gave a smaller file size of 834KB...



Shoot, even saving a PNG in Windows 7 MSpaint resulted in a smaller file size of 848KB, and MSpaint is notorious for having very unoptimized PNG compression.





For a bit of perspective from the other extreme, running the same image through the program "APNG Optimizer" with default settings resulted in a filesize of only 448KB (see attached).