Re: [darktable-dev] denoise profile non local means: neighborhood parameter

hi, that doesn't sound like a bad idea at all. for what it's worth, in practice the nlmeans doesn't let any grain at all through due to the piecewise constant prior that it's based on. well, only in regions where it finds enough other patches that is. in the current implementation with a radius

Re: [darktable-dev] denoise profile non local means: neighborhood parameter

Hi, The problem of a 2-passes denoising method involving 2 differents algorithms, the later applied where the former failed, could be the grain structure (the shape of the noise) would be different along the picture, thus very unpleasing. I thought maybe we could instead create some sort of

Re: [darktable-dev] denoise profile non local means: neighborhood parameter

Hi Yes, the patch size is set to 1 from the GUI, so it is not a bilateral filter, and I guess it corresponds to a patch window size of 3x3 in the code. The runtime difference is near the expected quadratic slowdown: 1,460 secs (8,379 CPU) for 7 and 12,794 secs (85,972 CPU) for 25, which means

Re: [darktable-dev] denoise profile non local means: neighborhood parameter

heya, thanks for the reference! interesting interpretation how the blotches form. not sure i'm entirely convinced by that argument. your image does look convincing though. let me get this right.. you ran with radius 1 which means patch window size 3x3? not 1x1 which would be a bilateral filter

Re: [darktable-dev] denoise profile non local means: neighborhood parameter

On Sat, 27 Jan 2018 05:34:24 +1100, rawfiner wrote: Thank you for your answer I perfectly agree with the fact that the GUI should not become overcomplicated. ...and neither should large attachments (9 MB) be sent directly to a mailing list. Please use a link to large

Re: [darktable-dev] denoise profile non local means: neighborhood parameter

hi, if you want, absolutely do play around with K. in my tests it did not lead to any better denoising. to my surprise a larger K often led to worse results (for some reason often the relevance of discovered patches decreases with distance from the current point). that's why K is not exposed in

[darktable-dev] denoise profile non local means: neighborhood parameter

Hi I am surprised to see that we cannot control the neighborhood parameter for the NLM algorithm (neither for the denoise non local mean, nor for the denoise profiled) from the GUI. I see in the code (denoiseprofile.c) this TODO that I don't understand: "// TODO: fixed K to use adaptive size