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In any standard there's usually a bit that isn't perfect, or it would not be a final specification. All specs I've seen up to now have at least one point you could improve on, which would require breaking the spec.Ozgunh82 wrote: I do not think that differentially encoding higher order dct coefficients will make you gain a lot, because if so they would have added it into jpeg speciication.
No, it's just plain a hunch. My reasoning went like, if you have an image, any texture will give a constant mapping to each DCTed square, so if you encode the diff rather than the file itself textures will be compressed further. I'm not sure whether common files have continual textures enough to compensate for it, but I think it'll improve compression on files with lots of changes and slightly enlarge files with few, which will (I think) mainly cause files to be compressed to a more common file size rather than dependant on the file content itself.do you have any theoretical proof for that?
Do you have any motivation for this?NotTheCHEAT wrote: This mathematics is beyond my understanding, but my non-expert opinion is: don't use JPEGs!
IIRC, JPEG wasn't patent covered. There was discussion about one patent possibly applying to it.Solar wrote: Probably ideology-motivated because JPEGs are patent-covered.
From TFA:
That would match JPEG kind of yes... but, not specifying the 2-dimensionality would have made it match somehow all lossy compressions nowadays.The patent describes a single-pass digital video compression system which implements a two-dimensional cosine transform with intraframe block-to-block comparisons of transform coefficients without need for preliminary statistical matching or preprocessing.
Each frame of the video image is divided into a predetermined matrix of spatial subframes or blocks. The system performs a spatial domain to transform domain transformation of the picture elements of each block to provide transform coefficients for each block. The system adaptively normalizes the transform coefficients so that the system generates data at a rate determined adaptively as a function of the fullness of a transmitter buffer. The transform coefficient data thus produced is encoded in accordance with amplitude Huffman codes and zero-coefficient runlength Huffman codes which are stored asynchronously in the transmitter buffer. The encoded data is output from the buffer at a synchronous rate for transmission through a limited-bandwidth medium. The system determines the buffer fullness and adaptively controls the rate at which data is generated so that the buffer is never completely emptied and never completely filled.