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Can you provide a link to the source?


- Tom
 

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Yes, it's possible in real time. I wrote up a filter like this, but decided that it didn't look all that great. It did help cartoons, but the blur in normal video looked a little odd, especially in regions where the contrast was near the threshold used to decide whether to average the colors.


It would be possible on a fast machine to check whether you're looking at a cartoonish image (lots of single color areas) and apply the "smart smoothing" only if the image contains a lot of low detail regions. But that would take a significant amount of memory bandwidth. I don't think it'll be worthwhile unless you have a very recent (fast RAM access, > 1 GHz) machine.
 

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Okay, it sounds like there would be some use for it, then. It's pretty straightforward -- just the current temporal noise filter tweaked to work spatially. Alternatively (or in addition), Tom might be able to take advantage of the sharpening or median code in GreedyHM to handle this without going over the entire screen of data, again.


Probably a good way to sense cartoons would be to check how often nearby (but not adjacent) pixels differ by more than a threshold. If too many differ, it's probably not a cartoon. To cut down on the memory access, you could do this just for part of the image.


A good thing about cartoons is that you can afford to use a much higher threshold to detect detail or motion -- In fact you can already improve cartoons by moving up the sliders on the temporal noise filter.
 

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Lindsey -


I wasn't really contemplating adding that. I was just curious.


BTW, I haven't really considered animation specific filters before. But it actually seems that posterization and reduced color depth might actually be an asset. ??


- Tom
 

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Yeah, if the image has lots of solid colors, posterization is what you're aiming for. But the (small) loss of color resolution is still a disadvantage.


With solid colors, though, noise is much easier to see. So it makes sense to sacrifice some resolution for a stable picture.
 

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On the topic of animation -- Is there a standard (or standards) for fields/frames of animation per second? If it isn't the same as for movies, a specialized pulldown detection method could be worthwhile.
 

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I've heard that animation can be a mix of almost anything.


Part of the goal in the greedy code doing pulldown matching instead of normal pulldown removal was to be able to handle this. That is, just match the correct adjacent fields together without demanding a correct recognizable pulldown pattern. But it still doesn't completely work without the pattern.


But it mostly does. The problem was just making the decision whether to match fields or deinterlace, on a field by field basis.


- Tom
 
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