lee@pipe.cs.wisc.edu (Soo Lee) (05/31/91)
Hi all, I am afraid that C-CUBE is changing their mind on JPEG chip. As I learned that DTC(Discrete Cosine Transformation) is implemented on JPEG chip, I am puzzled why they didn't switch to WAVELET algorithm which appears better, cheaper and faster than DTC algorithm. I agree that WAVELET comes later that DTC as JPEG emerges its standard but they could switch its standard in the infancy of WAVELET. Since Postscript II has internal DTC filter, it is not highly likely for NeXT to change daughterboard with WAVELET soon. However, performancewise, NeXT would rather change its compression support in the favor of WAVELET algorithm if daughterboard design won't cost much. Is there anyone who can tell me what is the future of "daughter board" of NeXTDimension could be? Soo lee@cs.wisc.edu
gmk@ucsc.edu (Gottfried Mayer-Kress) (06/01/91)
In article <1991May30.233044.7890@spool.cs.wisc.edu> lee@pipe.cs.wisc.edu (Soo Lee) writes: > Hi all, > > I am afraid that C-CUBE is changing their mind on JPEG chip. As I learned > that DTC(Discrete Cosine Transformation) is implemented on JPEG chip, I am I was also thinking about it. I have seen a demo by Gilbert Strang of a English product with a compression factor of 80-100 video compression and pretty good quality. Is there a way to just get one of those chips as an add on even before NeXT makes an official decision? Gottfried Mayer-Kress
thomsen@spf.trw.com (Mark R. Thomsen) (06/02/91)
Soo Lee writes Hi all, I am afraid that C-CUBE is changing their mind on JPEG chip. As I learned that DTC(Discrete Cosine Transformation) is implemented on JPEG chip, I am puzzled why they didn't switch to WAVELET algorithm which appears better, cheaper and faster than DTC algorithm. <more discussion to support this> It is not clear from our work here that a Wavelet (nee Gabor logon) compression approach is better, cheaper, or faster. While decompression is almost definitely faster, compression has proven to be slow. The main problem we see in JPEG has been energy loss when dropping DCT coefficients. To preserve energy would require more computations and decision branches in the algorithm - making chips more expensive and forbidding designs. The lossy Wavelet approach has an energy drop too, though the artifacts are different. The differences is better or worse depending on the image used and the viewer ... too subjective. I think there is so much work to be done in image compression that it is premature to fixate on a single approach. If a C-Cube chip is low enough price and can support 20:1 ratios to match NTSC:disk drive then it is fine, until the dust settles a bit more. With the JPEG push there will be low commercial support for Wavelet chips, software, and file exchange for a while. Use the first standard to enhance exchange and functions until there truely is a better algorithmic chip/circuit. Of course, it would be lovely if the daughter board approach could support such a switch in the future. Mark R. Thomsen