Avisynth: How Come Not Many People use Lanczos Resizing?

audi2honda · #1 06-15-2003, 09:04 PM

Hi I'm a first time poster. I am a DVD2SVCD user and found a link to this site over on doom9. I tell you from the first sample clip I did with the optimal script here and TOK I am seriously impressed with the quality. WOW you guys are on to something over here.

Anyway I'm from the digital photography world and allways found Lanczos resizing to be superior in quality. I've been using it with the AVIsynth scripts here and my first TOK KVCD movie is encoding right now.

I'm pretty excited about the quality I saw in my 5 minute clip, but am curious why everyone uses bilinear and bicubic. Is it because Lanczos is slower or you don't like the quality?

Also I'm used to using CCE 4 pass VBR and see lots of talk about TMG CQ. What CQ is considered good? Any reading you can point me to on this. I searched but didn't see any.

Seems like lots of sharp people here. Keep up the good work.

kwag · #2 06-15-2003, 10:04 PM

Hi audi2honda,

Welcome

About Lanczos, it's a very good resizer, but the problem is that it produces sharper edges than bicubic or bilinear, and the end result is more visible artifacts. We've found, after many many tests, that the best compromise is Bicubic.
As for CCE, well, it's excelent on MPEG-2 but not on MPEG-1. TMPEG just blows it away every time, specially in CQ mode. Have a look at this (LONG) but very interesting thread

http://www.kvcd.net/forum/viewtopic.php?t=2073

-kwag

audi2honda · #3 06-16-2003, 09:32 AM

Thanks kwag I'll give Bicubic a try. I just had a thought and realized my logic is backward. In digital photography I used Lanzcos for upward interpolation and making large prints of low resolution images. This produced the smoothest and best image, but we aren't interpolating here! duh

We are downsizing so I guess it's a whole new ballgame.

Thanks!

sh0dan · #4 06-16-2003, 02:16 PM

@audi2honda: Actually the same algorithms are used for both upsizing and downsizing. Lanczos IS the best to use - but the sharper image has the downside that it might look uglier when it is compressed.

You might have experienced that a JPEG at the same quality settings is bigger when using lanczos compared to bicubic. The same goes for video compression. So if it is possible I try to use lanczos - but if it actually make my encode look uglier I switch to bicubic, if I cannot get other filters make the source more compressible, without loosing too much detail..