[XviD-devel] image preprocessing

["Michael Militzer" <michael@xxxxxxxx>]

Hi all,

 

I experimented with some preprocessing filters again yesterday. I used a 3x3 averaging filter kernel as well as a symmetric 7-tap low-pass one. Results are similar with both filters: The PSNR values between the unfiltered source and the filtered reconstructed images are much lower than without filtering, but that's of course no surprise: One can't expect that such prefiltering brings you closer to the original (PSNR-wise).

 

However the PSNR values between filtered source and filtered reconstructed images are (depending on the strength of the filters) significantly better than their unfiltered equivalents. This proves that such prefilters help to avoid coding artifacts, so as long as the filtered image remains pleasing to the human eye (and I'd say it does), even such a simple prefiltering step can be an improvement.

 

btw: does someone know what sort of filter divx5 uses? I did a divx5 encode with preprocessing yesterday and the result looked somewhat strange...

 

bye

Michael