I won't pretend I really know what I'm talking about, I'm just guessing here, but don't you think the requirement for "independent and identically-distributed random variable data" in Shannon's source coding theorem may not be applicable to pictures, sounds or frame sequences normally handled by compression algorithms? I mean, many compression techniques rely on domain knowledge about the things to be compressed. For instance, a complex picture or video sequence may consist of a well-known background with a few characters from a well-known inventory in well-known positions. If you know those facts, you can increase the compression dramatically. A practical example may be Xtranormal stories, where you get a cute 3-D animated dialogue from a small script.
Best, -Martin On Sun, Mar 11, 2012 at 7:53 PM, BGB <cr88...@gmail.com> wrote: > On 3/11/2012 5:28 AM, Jakub Piotr Cłapa wrote: >> >> On 28.02.12 06:42, BGB wrote: >>> >>> but, anyways, here is a link to another article: >>> http://en.wikipedia.org/wiki/Shannon%27s_source_coding_theorem >> >> >> Shannon's theory applies to lossless transmission. I doubt anybody here >> wants to reproduce everything down to the timings and bugs of the original >> software. Information theory is not thermodynamics. >> > > Shannon's theory also applies some to lossy transmission, as it also sets a > lower bound on the size of the data as expressed with a certain degree of > loss. > > this is why, for example, with JPEGs or MP3s, getting a smaller size tends > to result in reduced quality. the higher quality can't be expressed in a > smaller size. _______________________________________________ fonc mailing list firstname.lastname@example.org http://vpri.org/mailman/listinfo/fonc