J. Grimbert <jgr### [at] atos-groupcom> wrote:
: JPG: the compression algorithm is with loss. Moreover the compression need
: a spatial transformation of the picture, which imply you will only have the
: file at the very end of the rendering (no Continue)

  Nope, you don't need the whole picture before being able to start the
conversion.
  When converting to the JPEG format, the original image is splitted into
square blocks (I don't remember how many pixels, but perhaps 8x8 or 16x16).
Then a fourier-transform is applied to each one of these blocks (with several
filterings which I don't know of) and finally (AFAIK) the result is compressed
into the final file. (Please correct my mistakes if I made any).
  This means that you need as many lines of the original image as the block
size at a time to be able to start compressing (ie. 8 or 16 lines).

: If you want a modern image format, go for PNG (and its already in POV).
: It's lossless, 24 (or even 48 bits), can have alpha information like gif
: and has no legal issue!

  Actually the GIF format does not support alpha channel. It supports marking
one of the colors as being transparent. This is not the same as an alpha
channel (ie. for each pixel you can say how transparent it is). PNG supports
it.

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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