[Photo] GREYCstoration

* dt -- strength of the smoothing factor (default: 50)
* p -- contour preservation (default: 0.8)
* a -- smoothing anisotropy (default: 0.8)
* alpha -- noise scale (default: 0.5)
* sigma -- geometry regularity (default: 1)
* iter -- number of iterations (default: 1)

greycstoration -restore before.jpg -dt 280 -p .7 -a .9 -sigma 2 -alpha .9
greycstoration -restore moule_original.png -a 0.1 -dt 100 -iter 2 -o moule_tuned.png

from http://jcornuz.wordpress.com/2008/01/04/denoising-with-greycstoration/


Command line for 16bits

From there, I decided to take my parameters into the command line version, which supports 16bits treatment. The equivalence between the plug-in and the command line version are straightforward:

strength :: -dt

contour preservation :: -p

anisotropy :: -a

noise scale :: -alpha

geometry regularity :: - sigma

spacial step :: -dl

angular step :: -da

approximation :: -fast

iterations :: -iter

interpolation algorithm :: -interp

so my command was:

greycstoration -restore ufraw_0.tif -bits 16 -o test.tif -dt 60 -p 0.7 -a 0.3 -alpha 5 -sigma 2.3 -dl 0.8 -da 30 -fast true -iter 1 -interp 2 -sdt 0

the -sdt 0 bit was to ask GREYCstoration not to do any sharpening on my image.

The processing to approximately for ever and a day to complete. GREYCstoration opens a windows with your image in it and when the processing is done, click on the window and press “S” for save. Check that the result image (test.tif in this case) is saved and then “Q” will quit. The result is the same image than in The Gimp but in 16bits precision.

What about luminance noise?

Call me crazy (if not already done) but I much rather like some luminance noise left than a water-colored image. In talking to the maintainer about my taste for luminance noise, he added an option to differentiate treatment on chroma vs luma noise. You can do that by using the -cbase 1 (0=RGB, 1=YCrCb) -crange 1,2 (0 is luma noise which we want to preserve). By the way, this options is currently only working in the command line version. The result is good, although it is possible to do better: