How lossy is DivX?
I have done some investigation in the field
"How lossy is DivX with different Quantizers?"
or
"What happens when I compress a DivX movie again with DivX?"
(Click here to see How
the file size is affected by the DivX quantizer.)
Here is the picture I compressed with DivX 5 Professional. Since most of DivX's optimizations are for movements (= movies), changing settings like bi-directional encoding wouldn't change anything here.
OK, here we go. This the original picture. (Well, all the
comparison pics you will see are jpegs, so this gives you a slightly worse quality, but they are saved
with a very low compression rate, so there won't be much difference to the original
.avi)
This is a special picture. It shows gradients of Red, Green, Blue, Cyan,
Magenta, Yellow, Gray to Black and to White. It shows tapering edges and round
edges. It shows contrasts from the colors mentioned above to Black. I agree,
that it's a little unfair, since DivX and other codecs are adjusted to do best
with real life pictures and scenes. But: This is a graphic to show the
weaknesses of DivX, not to praise it. It's being praised anyway. Besides, the
bad things you will see on these pages, you WILL see on your footage. And to an
even greater amount if your footage is comic like. So the
artefacts are not only theoretical.
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Click here to view how much you increase quality by modifying
the DivX quantizer.
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Click here to start the show for compressing a DivX
(100% Quantizer) to a DivX (100% Quantizer) to a DivX (100% Quantizer)...
Click here to start the show for compressing a DivX
(93% Quantizer) to a DivX (93% Quantizer) to a DivX (93% Quantizer)...