Possible to increase IQ for a undersize avi ?

[mikemak]

I know there has been a lot of discussion about undersize file already, but I wonder if any one here has any suggestions in improving the image quality for a undersize avi. I know a lot of people has suggested to either have more keyframes/ disable b-frame to get the right file size, however file size is not my concern at all. I recently encode some movies that are heavily undersized. Most of them are good but a few of them does not have good image quality. One of the example is the "bullet proof monk" which has a lot of dark scenes and does not have vivid color(bright color/contrast). The dvd looks really sharp and detail, but the encoded avi looks dull and blur. I don't care about the file size as long as the movie looks good. I have tried disable b-frames but the result is only a bigger file size with almost zero improvement on quality. While inserting more keyframes does improve the quality a little bit, but the final result is still not the quality that I am looking for, and I still have almost 300 MB space left for my target size. I have also tried many other tricks and I do get a bigger file size than before, but not much improvement on the quality of the picture. I noticed that there has been a lot of discussion on custom matrix lately on the forum, and I wonder if that would help in my situation. Any one here who has suggestions on how to improve the quality of a undersize avi is greatly appreciated! Thanks!
Note: I am Not looking for a bigger file size, but a way which actually can increase the Image quality of an undersized movie.

[Teegedeck]

An obvious idea would be to increase saturation or play with the levels. Anyone else?

[Koepi]

Well, you should modify your avisynth script and add:

Unfilter(+10,+10)

change your resizer to

LanczosResize()

This will add sharpness to your movie, resulting in "more noise" to encode - which on one hand raises the bitrate and should have visible effects (increased quality in this case) as well.

I wouldn't recommand that unfilter for bright or colour-saturated movies as it will cause artefacts there (oversharpening the source), but in this case it could work.

Use MPEG quant type.

Just in case, you didn't post either your settings/avs script or even the build you're using, so it's very hard to guess what you could do.

I hope this helps,

regards
Koepi

[mikemak]

Thanks Koepi and Teegedeck for your suggestions.
I don't usually use any special filter in my avisynth script for DVD encoding because I think the source has a very good quality and any filter like msharpen will make the codec compress much less (which is the case when I apply them to my video capture which produce a much bigger size) and thus hurt the final quality because the compression is not as good. And I admit that this time Koepi and Teegedeck is absolutely right and I will certainly try some filters and hopefully this will solve my problem.
How about custom matrices? As I heard sometimes they can produce better images with a bigger file size. Do those custom matrices have any effect on a undersized/saturated avi?

[mf]

Use CG Matrix and maybe UnSmooth (http://mf.creations.nl/avs/functions/UnSmooth-v0.1.avs) (my latest creation :D). Use unsmooth only if your DVD has very little to no artifacts, as it will also amplify these. You won't get any sharpening halos like with Unfilter or Lanczos.