Marco Antonio Simon dal Poz wrote:
>
> On Mon, 1 Feb 1999 [EMAIL PROTECTED] wrote:
>
> > But you won't have the original image. An especially in images with
> sharp
> > edges (which occur often in MSX pictures!) you will lose _lots_ of
> detail
> > even if you use 90% quality -- it's simply a consequence of the
> compression
> > method used. Just try it: make a simple image, preferably on your
> MSX :-):
> > a purple square on a yellow background. Save it as bitmap, and
> convert it to
> > a JPG. There is NO way you will retain the sharp edges in the JPG...
>
> Exactly. JPEG was designed specially for compressing of real images
> (i.e.,
> photos or digitally acquired images), and is based in the fact that
> usual
> images don't have abrupt transitions of color and human's eyes have
> less
> optical resolution in chrominance than luminance.
>
> GIF was designed as a simple method of compression based only in
> statistical factors, that is excellent for drawings and synthesized
> images, like games, and is based in the fact that drawings have too
> much
> equal colors (i.e., drawings have big areas with exactly the same
> color).
>
> Conclusion: use the right method on the right picture (and at the
> right
> time!)
>
Or adapt the image to the methode :-)
Since jpeg works on 8x8 pixelblocks you CAN retain the yellow square on
the purple background if you draw the square like this
LINE (8*x1,8*y1)-(8*x2-1,8*y2-1),,bf
Ofcourse if, like some programs do, there is a smoothing filter active
right after the image is restored then this filter will 'destroy' the
rectangle
David Heremans
--
"How should I know if it works? That's what beta testers
are for. I only coded it."
(Attributed to Linus Torvalds, somewhere in a posting)
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