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Old 19th June 2008, 01:32   #1  |  Link
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selective denoising

Apologies for a couple of noob questions:

1. I've been trying to find a way to apply a denoise filter to only the U-channel in YUV, (or R-channel in RGB) leaving the other 2 channels alone. Please can anyone suggest a filter or method for achieving this ? So far I've only come across Luma/Chroma filters - I need to get inside the Chroma ...

2. I was also admiring the hue-selector in Tweak ... I wondered if there is something similar for RGB/YUV levels somewhere ?

Any pointers much appreciated.
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Old 19th June 2008, 08:27   #2  |  Link
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1. UtoY and YToUV (see example on that page).

2. RGBAdjust and ColorYUV.
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Old 19th June 2008, 08:44   #3  |  Link
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Also ShowRed, ShowGreen, ShowBlue and MergeRGB
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Old 19th June 2008, 09:15   #4  |  Link
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dfttest and FFT3DFilter (FFT3dGPU) are candidates for such approach.

Last edited by Archimedes; 19th June 2008 at 09:18.
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Old 19th June 2008, 15:15   #5  |  Link
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fft3dfilter(plane=1) will only filter U.
dfttest(Y=false, U= true, V=false) will only filter U (I think)
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Old 19th June 2008, 15:57   #6  |  Link
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You could use Cnr2:
"Cnr2 is a chroma temporal smoother (it wont touch luma), mainly aimed at tv/analogue captures. It is quite fast and very good at removing the typical chroma artifacts that can be present in captures."
Download at: http://web.missouri.edu/~kes25c/cnr2_v261.zip
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Old 20th June 2008, 05:03   #7  |  Link
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Yeah, for chroma noise it's hard to beat fft3dfilter. It's VERY good.

I usually start with plane=3, and sigma=2, then do UtoY or VtoY, and check for banding. If it's present, I either reduce global sigma, or roll-off strength - like sigma=2, sigma2=1.6, sigma3=1.2, sigma4=.8.. Now with Psy-RDO x264, I can follow with Gradfun2db, and dither away any remaining banding.

These are all my personal statements, not those of my employer :)
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