On Thu, Nov 3, 2016 at 9:49 PM, Oliver Bedford <oliver.bedf...@yahoo.de> wrote: > It seems the profiled denoise does produce some artefacts, which look > like hot pixels (and aren't visible in the original image or are buried > under the extreme colour noise). You can combat this side effect with > the dead pixel module. .. Except you can't. Hot pixels module is located earlier in the pipe than the denoise profiled.
Providing invalid suggestions seems to be the new normal for mail-lists... > There's also a "large-scale" colour noise present, for which you can use > the equalizer module (apply chrominance denoise only for coarse > structures). > > raw denoise might also be added (not too much in order not to lose > detail). > > You're also doing some things in post, which add visual colour noise: > increase contrast with the tone curve, sharpening, and setting the white > balance manually. > > Personally I would go for a low contrast look (remove the base curve) > and finally convert to gray scale (but that's a matter of personal > taste). > > xml attached > > Regards, > Oliver Roman. > Am Donnerstag, den 03.11.2016, 12:53 -0400 schrieb Andy: >> Thank you all for the answers, and sorry I misinterpreted the raw >> demosaic. >> >> FYI, here are some (screenshot) samples using the standard demosaic. >> The large images are no denoise, color denoise and HSV color denoise, >> while the small are no denoise and colordenoise. >> On the small image you can see the bright green in the highlights, in >> the larger images you can see how there are pretty strong color >> changes. >> Is there any way to combat this? >> I've been trying to get some setting that gets close to the build-in >> processing. The JPEG that come out the camera are way better than any >> denoising >> I could achieve so far :( >> >> >> >> On 11/03/2016 12:15 PM, Roman Lebedev wrote: >> >> > On Thu, Nov 3, 2016 at 6:59 PM, KOVÁCS István <k...@kovacs-telekes.org> >> > wrote: >> > > The HSV-based solutions look inferior to me. Last September, I started >> > > a thread, but it did not get far. See the message quoted below - the >> > > sample images are available at >> > > http://tech.kovacs-telekes.org/files/dt_profiled_denoise_colour_vs_hsv_colour/ >> > > >> > > Thanks, >> > > Kofa >> > > >> > > >> > > >> > > ---------- Forwarded message ---------- >> > > From: Stéphane Gourichon <stephane_darkta...@gourichon.org> >> > > Date: 12 September 2015 at 09:19 >> > > Subject: Re: [Darktable-users] profiled denoise - colour vs HSV colour >> > > To: darktable-us...@lists.sourceforge.net >> > > >> > > >> > > Le 11/09/2015 22:44, KOVÁCS István a écrit : >> > > >> > > Even when fit to the screen (1920x1080), I find the plain >> > > 'colour'-blended version (DSC_8834.jpg) less noisy *and* sharper than >> > > the HSV-colour-blended one (DSC_8834_01.jpg). Zoomed in, the noise >> > > seems more 'patterned' on the HSV-blended version (shows some kinds of >> > > structure, patches, homogeneous areas with more defined, thicker >> > > borders). >> > > >> > > >> > > The better noise characteristic you mention (better on DSC_8834.jpg >> > > than on DSC_8834_01.jpg) seems pretty clear to me. >> > > >> > > From my experience, the pattern you mention have similar size as >> > > typical *color* noise patterns in photographs. >> > > >> > > I'm not a human vision specialist yet have some past experience during >> > > my Ph.D. in robotic vision where the colorspace used for computation >> > > has sometimes important impact on the effectiveness/robustness of some >> > > algorithms. >> > > >> > > In the case of your observation, I would guess it is related to the >> > > fact that performing image operations on HSV colorspace misfits/mixes >> > > what human vision perceives as luma and chroma. As a consequence, the >> > > noise reduction performed on S and V "bleeds" into what the eye >> > > perceive as luminance, where it appears as the patterned noise you >> > > mention. This theory goes in the same direction as your observation. >> > > >> > > For more information, read the paragraphs above and below the turtle >> > > photographs on https://en.wikipedia.org/wiki/HSL_and_HSV#Disadvantages >> > > >> > > Can anyone elaborate the difference between "color" and "chroma" >> > > blending mode in this respect ? >> > This may have been pointed out already, but >> > https://github.com/darktable-org/darktable/blob/master/src/develop/blend.c#L2035-L2036 >> > _blend_color(): color blend; blend hue and chroma, but not lightness - >> > blend hue along shortest distance on color circle >> > >> > https://github.com/darktable-org/darktable/blob/master/src/develop/blend.c#L1898-L1899 >> > _blend_chroma(): chroma blend - just blends C channel in LCH (for Lab >> > based iops), or S channel in HSL (for RGB based iops) >> > >> > > Regards, >> > > >> > > -- >> > > Stéphane Gourichon >> > Roman. >> > >> > > ------------------------------------------------------------------------------ >> > > >> > > _______________________________________________ >> > > Darktable-users mailing list >> > > darktable-us...@lists.sourceforge.net >> > > https://lists.sourceforge.net/lists/listinfo/darktable-users >> > > >> > > On 3 November 2016 at 16:18, Roman Lebedev <lebedev...@gmail.com> wrote: >> > > > On Thu, Nov 3, 2016 at 5:57 PM, Andy <t3k...@gmail.com> wrote: >> > > > > Hi all. >> > > > > I'm new to darktable and somewhat new to raw image processing so >> > > > > please >> > > > > excuse me if this is a naive question. >> > > > > I was trying to denoise some images from my Sony a7 II R shot at >> > > > > 51200 ISO. >> > > > > I followed some tutorials that recommended applying wavelet denoise >> > > > > with >> > > > > blend=color and non-local means with blend=lightness. >> > > > Also do try blend=hsv color and blend=hsv lightness. >> > > > >> > > > > I noticed some bright green highlights appearing. I played around >> > > > > with the >> > > > > demosaic-ing and noticed that it even happened with >> > > > > the "rough monochrome" demoisaicing and so I thought it might be >> > > > > worth >> > > > > asking if this is a bug or some odd interaction of the filters. >> > > > > You can find a picture here: >> > > > > https://whttps://www.dropbox.com/s/ozjy3dk84zgvs6s/DSC00961.ARW?dl=0 >> > > > > and the >> > > > > xmp here: ww.dropbox.com/s/fr24nz7zgz7xgd9/DSC00961.ARW.xmp?dl=0 >> > > > > >> > > > > If you go to the highest zoom level with wavelet denoising on the >> > > > > color and >> > > > > raw monochrome demosaic, you will see the bright green artifacts. >> > > > Monochrome demosaic is NOT meant to be used to "monochromly" demosaic >> > > > the normal raw files. It is only meant to be used for the raw files >> > > > from cameras >> > > > with color filter array physically removed, scraped off. >> > > > >> > > > > They disappear when disabling the color denoising with wavelets. >> > > > The profiled denoise is tuned to the properly-demosaiced image. >> > > > If it does exhibit some artifacts when used on non-demosaiced input >> > > > (because that is basically what monochrome demosaic does), >> > > > i would not be surprised. >> > > > Because monochrome is, as far i'm concerned, the exact opposite of >> > > > color. >> > > > >> > > > > Using any other demosaic algorithm, you'll see magenta artifacts in >> > > > > the >> > > > > highlights as soon as you turn the color denoising on. >> > > > > My question is: is this expected? In particular with the monochrome >> > > > > demosaic >> > > > > the artifacts seem very odd. >> > > > I'd *personally* say yes. >> > > > >> > > > > But in general >> > > > > I'd love to get rid of the bright green / magenta artefacts in the >> > > > > highlights when doing the color denoise. >> > > > > >> > > > > Thank you! >> > > > > >> > > > > Andy >> > > > Roman. >> > > > >> > > > > ____________________________________________________________________________ >> > > > > 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 >> > > > >> >> >> ____________________________________________________________________________ >> 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
