I kind of solved the problem now thanks to your denoising screencast, Pascal. I am aware, that raw pictures are RAW and not processed like the out of cam jpgs. But it my case the raw files, heavily denoised by darktable, were - after converting them to jpgs - much noisier than the ooc jpgs. Ok, now the clue: I learned that the denoising function I used (bilateral filter denoising) is very demanding for the system, which in my case is a 6 year old notebook... So, by trying to execute the bilateral filter denoiser, my notebook kind of destroyed the pictures with heavy noise (which by the way took 10 minutes per picture). Using the "non-local means denoising" the result looks not as perfect as the bilateral filter inside darktable, but much better as exported jpg, and it's faster too.
One more thing: It is still a little bit noisier with the gnome image viewer than opening it in gimp, but that's probably due to the different resampling as you mentioned before. Problem solved. Thanks a lot, Pascal! Tobias, thank you too for your kind help. Nico Am 18.01.2013 17:58, schrieb Pascal de Bruijn: > On Fri, Jan 18, 2013 at 1:06 AM, Nico Wöhrle <[email protected]> wrote: >> Thanks for the answers. >> >> @ Tobias: the images look noisy in every zoom level, also in 100%. >> >> What I don't get about the "it is the image viewer" thing. My camera >> produced a RAW and a JPG file. The JPG processed from the RAW file (with >> darktable) looks by orders of magnitude noisier than the JPG which came >> directly from the camera. I don't understand why the gnome image viewer is >> able to show a normal JPG "correctly", but not a JPG coming from darktable. > I have a feeling you are confusing two unrelated issues. > > a. Different programs resample images using different algorithms, > which may enhance sharpness (and increase apparent noise) or decrease > sharpness (and decrease apparent noise). > > b. Also Darktable does not denoise your RAW files by default. And thus > is noisier than your camera generated files. Also completely expected. > > RAW files are not simple uncompressed files. It's a raw sensor > capture, which requires a boatload of processing to even get a half > decent image. Some of the things camera's do are > 1. Demosaicing > 2. Curves > 3. Color processing > 4. Image dependent analysis and correction (Nikon Active D-light/Canon > Auto Lighting Optimizer/... on newer models). > 5. Denoising > 6. Sharpening > > Most things about processing RAW files are camera specific and > completely undocumented/proprietary. > > The particular problem with denoising is that everybody has different > preferences, and more importantly it's very CPU intensive > (particularly noticeable on older computers), so it's not enabled by > default. > > Our website lists some of my screencasts on Darktable usage in > general, and it even has a screencast specifically about denoising > (using the nlmeans plugin): > > http://www.darktable.org/resources/#screencasts > > Regards, > Pascal de Bruijn > ------------------------------------------------------------------------------ Master HTML5, CSS3, ASP.NET, MVC, AJAX, Knockout.js, Web API and much more. Get web development skills now with LearnDevNow - 350+ hours of step-by-step video tutorials by Microsoft MVPs and experts. SALE $99.99 this month only -- learn more at: http://p.sf.net/sfu/learnmore_122812 _______________________________________________ darktable-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/darktable-devel
