"Warp" <war### [at] tagpovrayorg> wrote:
>   No-one said that a compression scheme should use just *one* compression
> algorithm.
>   The simples case of using two algorithms is: First try compressing
> with the compression algorithm, and if the result is bigger than the
> original, just store the raw image.
>   This way some of the images will be smaller than the original and some
> will be equal. None of the images will be larger than the original.
>   This way the overall average compression rate will be higher than 1.

nope !

you have to store at least one bit more (for every image), telling you which
of the both algorithms to use.

Of course, in practice you could tell this probably tell this from the filename
(*hey-idea*: why not store the whole image-data in the filename ? ;), but in theorie
there's nothing like an "filename". So these additional bits would make the
o-a-c-r at least 1.

Assuming, of course, we're speaking 'bout lossless compression ...

This all is coveres by the chapter about kolmogorov-complexity...

Post a reply to this message