As probably many people around here I read a few webcomics. Drowtales is my favorite, but that’s besides the point.
For a long time a thought has been nagging me at the back of my head: webcomics are drawn pictures. They are not photographs. There should be a lot of redundancy (less colors, more flat colored areas, etc.) and thus they should be easily compressible at quite high rates while still maintaining lossless quality. Still it seems that the best tool to compress them is the same old lossy JPEG.
How so? Are there not better things invented? I’m not an expert in data compression, so my own meager attempts at finding some better algorithm have been fruitless. Best I could find was Pngcrush, but it still is way behind JPEG in terms of compression.
I would like to hear an expert opinion on this. Is this idea of mine foolish and doomed to failure? Or is there perhaps some way that people have found or that I could look into?
This, of course, comes from the selfish desire to decrease load times. 🙂
Added: Some people seem to miss the point, so I’ll clarify:
Webcomic images should have a lot of redundancy in them so they should be easily compressible. Is it not possible to somehow compress them so that they would be both lossless AND smaller than JPEG? Or at the very least compress them better than JPEG while still retaining the quality.
Since they would be for web the specialized compressor should still probably emit PNG or JPEG – just compressed with a modified algorithm for better results.
The problem with comics is that a lot of graduated colouring is used. A common technique when colouring a comic on computer using Photoshop, for example, is to start by blocking out areas in solid colour as you mentioned. However, these solid areas are then refined using various techniques, from hand touching using airbrush tools to overlaying graduated fills, dodging and burning tools, etc.
The result is an image which is more like a natural image – which is what comic artists are striving for of course – and thus it compresses better with a lossy algorithm such as that used by JPEG.