hi, On Sun, Dec 11, 2016 at 3:09 AM, PkmX <pkmx...@gmail.com> wrote: > Hi, > > I'd like to share my own experiences of dealing with extremely noisy > images with darktable as well. For comparison I'm going to use the ARW > image from this thread: > https://discuss.pixls.us/t/playraw-high-iso-challenge/2778, since it's > a rather difficult image to work with. I will be using AMaZE for > demoasicing and Rec.2020 as the input color profile since it works > much better than the default matrix of Sony A6000 in my experience. > The applied-by-default base curves and sharpening modules are also > disabled. > > This is the RAW image with no denoising applied, to give an idea how > bad the noises are in the photo: > http://i.imgur.com/AgxvKby.jpg > > For reference this is denoised with RawTherapee with mode = lab, > quality = high, luminance = 20, luminance detail = 10, automatic > global chroma denoise, 3x3 median filter: > http://i.imgur.com/hiXMklL.jpg > RawTherapee eliminated nearly all chromatic noise and the luma noise > left in the background are very fine and looks pretty non-obtrusive. > It also preserves the details on the dog fur very nicely. > > The first attempt with darktable is using the recommended profiled > denoise module in NLM mode on HSV lightness and another in Wavelet > mode with HSV color at default strength: > http://i.imgur.com/WGN5Y03.jpg > This produces some blotches of luma noise in the background area which > in my opinion is very distracting (which is further complicated by the > fact that it brightens up the darker areas which makes it look worse). > There are still larger patches of colorful noise visible and the > details on the fur are almost completely wiped out. > > This another attempt using profile denoise. This time I switched to > wavelet mode in the lightness instance with 50% blend to combat the > blotchness, turned the strength of wavelet chromatic denoise to 4.0, > and set color smoothing in AMaZE to 5 times: > http://i.imgur.com/YaBAAJR.jpg > This eliminates more noises while keeping a lot more details in the > fur, but there are still some patterns visible in the background. The > whole image also got a purple tint and at 100% view you can easily see > some of those purple artifacts in the darker areas of image. > > The next is probably my go-to way of noise removal on high ISO images > in darktable now. I used the equalizer's denoise preset with mix 2.0 > and the lowpass module with radius=10 and lab color blending to apply > a really strong chromatic denoise: > http://i.imgur.com/wx0QGZN.jpg > This looks a lot better even though some colorful patches are still > visible in the darker areas, and the luma noise are now very similar > to the result of RawTherapee. The downside is that it desaturates the > image and smears the color (compare the red heart in the bottom-right > corner, though it also removes the CA so I guess it isn't too bad :)). > The processing is super fast compared to profiled denoise. > > This is another attempt, this time using the "denoise (bilateral > filter)" instead of lowpass. > http://i.imgur.com/I4WIvQy.jpg > This wipes out all chromatic noise but also seems to wash out the > photo and give it a slight purple tint. > > Finally, this is the result of aforementioned denoise_chinese dtstyle: > http://i.imgur.com/NrQy3NV.jpg > I guess the strength of noise removal of the style isn't high enough > for this image.
my try: https://jo.dreggn.org/noisydog.jpg xmp in jpg: something with near linear base curve, equalizer, and no sharpening. not sure about the colours, they are just different. in general for such super high iso noise the noise profiles are often times off due to strange effects (noise model breaking down, vendor pre-processing or whatever). also i find i can get better results with manual equalizer operation than with the profiled denoising, but that's a matter of taste and time i want to spend on an image. -jo > > Overall I'd say RawTherapee's result is the best as it removes almost > all chromatic noises without causing color casts or artifacts, and it > produces very fine and non-obtrusive luma noise. Darktable with > equalizer and lowpass modules comes close, but the other results look > unacceptable to me. > > I really would like to know a way of noise removal that can rival > RawTherapee since I like darktable's workflow more, so please let us > know if you do discover one. :) > > PkmX > ____________________________________________________________________________ > darktable user mailing list > to unsubscribe send a mail to darktable-user+unsubscr...@lists.darktable.org > ____________________________________________________________________________ darktable user mailing list to unsubscribe send a mail to darktable-user+unsubscr...@lists.darktable.org
