Great, Jo! I've never understood the purpose of this method. Maybe now the time has come for me to understand it.
(out of this topic, I've never used the HotPixels module before a couple of weeks, when some photos shot at night, toward a source of light, showed 2 or 3 pixels, one red, another blue, in the middle of the black area. First I thought about spot removal, but then... I turned Mark Hot Pixels on and voilá, those pixels vanished! Great! [if anyone wants to explain what's that, you're welcome]) I'll try the dithering when I get home, tonight, and post the results later. Thank you all. André 2015-11-12 12:18 GMT-02:00 johannes hanika <hana...@gmail.com>: > right, this kind of artifact results from low bit depth even for > perfect images without noise reduction. ulrich wrote the dithering > module to counteract that: > > http://www.darktable.org/usermanual/ch03s04s04.html.php#dithering > > might be helpful in your case, too. > cheers, > jo > > On Thu, Nov 12, 2015 at 3:08 PM, André Felipe Carvalho > <afelipe.carva...@gmail.com> wrote: > > This photo was saved in jpeg 100%, raw denoising of 0.004. I managed to > get > > rid of the majority of the bands, but you can see some lines above/around > > the sun. > > https://www.flickr.com/photos/andrefelipecarvalho/22536463868/ > > > > > > > > 2015-11-11 22:34 GMT-02:00 André Felipe Carvalho > > <afelipe.carva...@gmail.com>: > >> > >> Hello Johannes, > >> > >> I was using Jpeg 97% > >> > >> I use, normally, only the raw denoising, starting with 0.002 points, > going > >> to 0.006 if needed and the image colors permit. > >> > >> Experimenting with 0.004 raw denoising I can see some band even with > the > >> PNG 100% export. But I admit it's better then at 97% jpeg. > >> The bands, now, are narrower than before. Less visible at the orange sky > >> parts and more apparent at the dark, silhouetted parts. > >> > >> Pulling the Color Balance first factor (Levantar, in portuguese) a > little > >> bit to the left may help to disguise the bands. > >> > >> Thanks again, > >> André > >> > >> > >> 2015-11-11 14:24 GMT-02:00 johannes hanika <hana...@gmail.com>: > >>> > >>> On Wed, Nov 11, 2015 at 11:05 PM, Tobias Ellinghaus <h...@gmx.de> > wrote: > >>> > Am Dienstag, 10. November 2015, 19:15:10 schrieb André Felipe > Carvalho: > >>> >> I've been experiencing this behavior specially in sunset photos. > >>> >> > >>> >> After applying the modules that I want, among them the sharpness > >>> >> module, if > >>> >> I want to get rid of the raw noise, the exported jpeg shows bands on > >>> >> the > >>> >> degrades parts of the image (sky, for instance, or dark areas). > >>> >> The exported image without Raw Noise Reduction is about 6.8MB, while > >>> >> the > >>> >> one with noise reduction goes down to 2.8MB. Why's that? > >>> > >>> that's normal, noise has high entropy and doesn't compress as well as > >>> the low noise one. > >>> > >>> did you only do raw denoising? or any non local means, too? any > >>> wavelet based method shouldn't lead to as much banding as nlmeans > >>> (because the latter uses a piecewise constant prior). > >>> > >>> -jo > >>> > >>> > > >>> > - What is your "quality" setting in the export module? > >>> > - Could you try exporting to PNG and see if that has the same > problems? > >>> > > >>> >> The IQ is bad (because of those bands) and I have to turn noise > >>> >> reduction > >>> >> off. > >>> >> > >>> >> I can provide some samples, or the raw file and the .xml associated. > >>> > > >>> > Tobias > >>> > > >>> > > ------------------------------------------------------------------------------ > >>> > > >>> > _______________________________________________ > >>> > Darktable-users mailing list > >>> > Darktable-users@lists.sourceforge.net > >>> > https://lists.sourceforge.net/lists/listinfo/darktable-users > >>> > > >>> > >>> > >>> > ------------------------------------------------------------------------------ > >>> _______________________________________________ > >>> Darktable-users mailing list > >>> Darktable-users@lists.sourceforge.net > >>> https://lists.sourceforge.net/lists/listinfo/darktable-users > >> > >> > >> > >> > >> -- > >> André Felipe > >> ============================================ > >> New beginnings are often disguised as painful endings. > >> > >> > -------------------------------------------------------------------------------- > >> Lao Tzu > >> ============================================ > > > > > > > > > > -- > > André Felipe > > ============================================ > > New beginnings are often disguised as painful endings. > > > > > -------------------------------------------------------------------------------- > > Lao Tzu > > ============================================ > > > > > ------------------------------------------------------------------------------ > > > > _______________________________________________ > > Darktable-users mailing list > > Darktable-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/darktable-users > > > -- André Felipe ============================================ New beginnings are often disguised as painful endings. -------------------------------------------------------------------------------- Lao Tzu ============================================
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