View Full Version : Dot Crawl after IVTC

Velocity 7
9th October 2006, 00:14
So suppose you come across some anime footage that's got dot crawl before it was IVTCed, and they didn't bother to clean up the dot crawl. What should one do?

9th October 2006, 00:33
umm, fix it?

9th October 2006, 00:42
TComb and/or DeDot? They might not get it all out, but they'll improve it. Or is it still bad afterward?

Velocity 7
9th October 2006, 01:11
Still some rainbowing and dot crawl leftover.

Mug Funky
9th October 2006, 01:11
i think bifrost has a before/after IVTC mode.

dedot wont work - it doesn't even work after soft telecine.

Velocity 7
9th October 2006, 01:24
SSIQ has a much better effect than Bifrost does for derainbowing, but is insanely slow. TComb also causes some ghosting despite having some effect.

So far I've only been able to rid some of it using RemoveDirt() but it's still terrible (not to mention somewhat slow, but faster than the above methods).

Here's some unprocessed footage for people to play with:

Dot crawl (http://naomi.thewafflehouse.net/dotcrawl.avi)
Rainbow + dot crawl (http://naomi.thewafflehouse.net/rainbow.avi)

9th October 2006, 02:29
Mug Funky, don't you remember that you once said that DeGrainMedian could reduce dotcrawl? I once used it with DeDot on a vob sample with lots of dotcrawling and managed to eliminate most of it.

As for DeRainbowing, BiFrost (if used properly, read its help file) and FFT3DFilter work wonders. I almost always use the latter, but both are great.

9th October 2006, 02:30
It is very unlikely that TComb will do anything useful on footage that has already been ivtced. For rainbow removal it requires a pixel to be static for a period of 5 fields of the same parity, and those fields must maintain the alternating 180 degree phase difference. If you perform ivtc, which removes 1 field out of every 5, it destroys the pattern.