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2011.07.28 18:19 "Re: Using photon lists rather than rasters", by Thomas Richter
On 28.07.2011 19:30, rwong_002@hotmail.com wrote: > The idea about a better predictor to improve compression of niche > scientific images is interesting. Though note that there are already many compression schemes available on the market that *do* use better prediction than TIFF. Tiff is always pretty close to the "bare metal", i.e. pixels in this context, and its compression schemes are rather simple. If better compression of *pixel* graphics is your concern, I suggest to have a look into JPEG-LS (a lossless compression format, not to be confused with JPEG or JPEG 2000) which is very fast and compresses pretty well. > Along the same direction, Terry could really use the new compression > type for that. Think about that: if it's a new predictor that nobody > today knows how to decode, and if it's much more advanced than today's > "TIFF predictor" (even though it is indeed a predictor in > mathematical/pedantic terms), it doesn't hurt to make its own > compression type. Maybe, but before doing that, it would be preferable to use something that is already on the market, and hence known by at least some software. You can still write your own if it turns out that the corresponding format doesn't fit your needs. But as others already said: A *pixel list* is surely not something I would fit into TIFF. > As for the photon images, it will require something superbly advanced > algorithms, something that blends several existing advanced algorithms > together that nobody has seen before. Like: multi-resolution (or > progressive-resolution), some kind of CABAC (which is both > context-sensitive and uses arithmetic coding), etc. Stuff like that is all available, why role your own? There is JPEG 2000 which does an excellent job, there is H.264 I-frame compression you might want to try. All designed by people with years of experience in this area. TIFF is, after all, mostly a container format; adding a new tag is not going to help anyone to view such images, while using an already existing scheme would. Whether any of the mentioned compression formats addresses your needs I don't know, but you should try. Greetings, Thomas