Can spatial sharpeners help deinterlacing?

[bilu]

Background info:

http://forum.doom9.org/showthread.php?s=&threadid=56201
(didn't answer there because it was getting OT)

My questions are:

Can spatial sharpeners help on field matching?
Or would they just amplify noise and make it difficult?

Can a spatial denoiser followed by a spatial sharpener improve field match better? Would it damage a movie? And anime?


Best regards,
Bilu

[trbarry]

I've played with this a little bit and it does seem you can get away with sharpening some after certain types of noise filters, say like UnDot or STMedianFilter or some others. I think the idea is to use the filters to remove the real statistical outliers and then sharpen the rest a small amount. But then it won't compress as well, and I usually do not do it.

It's a different story trying to sharpen after deinterlacing. Most deinterlacers of almost all types will leave a little vertical aliasing or artifacts of some sort and I do not think it is good to vertically sharpen after this. It can amplify those artifacts. Instead I like the option built into my deinterlacers to vertically soften just a tiny bit when deinterlacing. This will compress better and avoid the rippling effect you can otherwise get when slowly panning over high detail areas.

- Tom

[bilu]

But what about sharpening before deinterlacing to improve field matching?

Bilu

[Guest]

I doubt it would help, because as you say, the noise too is sharpened.

It's an easy experiment to try, though; why don't you?

[bilu]

I can try it, but I have reserves too.

If you smooth the noise and the use some edge-directed sharpener, it could help. But it can damage the picture.

Moreover transformations over the original picture may not be the same over the same field:

Imagine a low-motion movement scene with trees and a little wind. They're bouncing back and forth.

Can't denoising or sharpening make Telecide miss the field match instead of improving it?


Guess I'll have to try then. :)


Bilu