Author Topic: Noise reduction for luminance masks  (Read 503 times)

Offline VoidPointer

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Noise reduction for luminance masks
« on: 2019 April 08 07:40:10 »
Hi,

When I'm using a inverted luminance mask to protect high-signal areas during noise reduction, I'm wondering whether it is beneficial to apply some form of noise-reduction to the luminance mask itself or whether that doesn't matter or might even be counter-productive.
Since the noise in the low-signal areas would make the mask noise in that areas I was thinking that that would render any noise reduction on those areas less effective. Is that a valid conclusion?
I've found that just applying some convolution (blurring) to the mask worked quite well especially when working with masks that were generated from a linear image and had to be stretched...

How do you deal with noise in luminance masks, if you worry about that at all? Does it mater?

Cheers!
Lars

Offline pfile

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Re: Noise reduction for luminance masks
« Reply #1 on: 2019 April 08 09:25:02 »
yes i think it is a common technique to smooth your mask a bit for this purpose. since the low SNR areas of your image are (by definition) noisy, the mask is also noisy in those areas which leads to a kind of an uneven noise reduction when applied thru such a mask.

i usually use atrous to remove 1-3 wavelets from the mask, depending on how noisy the mask seems to be.

rob

Offline VoidPointer

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Re: Noise reduction for luminance masks
« Reply #2 on: 2019 April 09 07:37:32 »
That's neat. Wavelets to the rescue once more. Thanks!