NLMeans denoise filter

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Re: NLMeans denoise filter

Post by BradleyS » Thu Aug 25, 2016 9:02 am

Interlacing typically only presents combing artifacts during periods of motion. Deinterlacers can sometimes be a bit brute for periods of lower or non-existent motion. Combing detection allows us to estimate the situation to process light or heavy combing differently, and frames with zero combing artifacts pass through untouched, just like progressive frames. All of this benefits image fidelity, specifically perceived sharpness.

You may be thinking, wouldn't sharpness in low motion scenes and less sharpness in high motion scenes be jarring? No, not really. Humans have a difficult time perceiving sharpness given sufficient motion (which is probably blurred in the source, natch), so there is no harsh transition to our eyes. Interestingly enough, we will typically perceive the entire video to be sharper. This is of course, somewhat subtle for some sources and more pronounced for others.

In short, decombing analyzes the video and then makes decisions. This is typically the way to go, though some will prefer to simply deinterlace interlaced video to eliminate the possibility of false negatives (rare but does happen, analysis is excellent but not perfect). Use what suits you.

This is a bit off topic, so perhaps a new topic would be more appropriate if anyone has additional non-NLMeans questions.

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