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.

1st Experiment How does the DivX quantizer affect the visible quality?

Click here to view how much you increase quality by modifying the DivX quantizer.

2nd Experiment How much quality do I lose by saving a DivX (mpeg) file as DivX?

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)...