One post on behalf of Pascal de Bruijn Hi,
Time to get some confusion out of the way. A typical complete camera input profile consist of two things: curves and an XYZ matrix. The default color processing of Darktable (and most other open source raw converters) use the Adobe DNG D65 XYZ color matrix (camera specific), but that means the curve is missing. Which we complement by applying a mostly brand specific basecurve. Other open source RAW converters complement the color matrix with a generic gamma curve (often 0.45 which is the inverse notation of 2.2). But UFRaw for example adds a linearity option (0.10 by default) which actually distorts that normal 2.2 gamma curve to increase contrast (read to make it look good), and the end result is probably not dissimilar to how our basecurves look, except that it's not tuned to a particular brand. The problem with this approach is that it leaves you with a discrepancy how the camera processes the RAW (most people seem to expect images in a RAW converter to look similar to what the camera generates). And there is no way to solve that without applying brand specific curves. So if you disable the basecurve in darktable it's completely expected that a RAW files will look dull, since the data is still linear (at least to the extent that the raw sensor data is linear to begin with) then. The idea that any particular approach would be "better" than any other is nonsense, and please do not spread the idea that it would be. It's just a preference nothing more. The difference between the curves: Basecurve in camera RGB (before colorin) Tonecurve in Lab colorspace (after colorin) This is made visible by turning off plugin grouping in darkroom mode, which I've demonstrated time and time again in my screencasts, so you can see the static order in which plugins are applied (bottom to top). These plugins account for everything being done, not just "corrections". Regards, Pascal de Bruijn On Sun, Dec 30, 2012 at 10:08 PM, Eckhart Pedersen <[email protected]> wrote: > Hi all, > > I have tried very hard to understand color management for years, and I think > I have finally understood the basics. I have now calibrated my Dell U2410 > with an i1 display pro colorimeter + DispcalGUI, installied the profile > system wide, and am now using this profile in darktable. I have even > verified the calibration and profile using the colorimeter and everything > seems to be ok. > > Calibration was done in standard mode of the display, 30 Brightness, 50 > contrast, and 6500K black body as whitepoint target. > > If I now load a raw image from my Canon EOS 5D II in darktable and disable > all processing (except sharpening), I would expect to get a usable/neutral > rendition of the photo on my display. However, the photos look very > dull/muted. Since darktable comes with an existing input profile for the 5D > II (it does, doesn't it?) I would expect the default look to look more or > less natural, without having to fiddle with curves, saturation, or contrast > in any way. But this does not seem to be true. It looks completely wrong. > > You can find an example image here. > > raw CR2: http://cornergraf.net/darktable.org/raw.CR2 > exported JPG with everything off, except sharpening: > http://cornergraf.net/darktable.org/muted2.jpg > exported JPG with black level +0.10, and exposure +1.3: > http://cornergraf.net/darktable.org/proper2.jpg > > Please help me understand what is going on here. Is this the way the files > should look like straight out of the camera and with no processing? Is my > display calibrated or profiled incorrectly? What do you get when you look at > the exported JPG files, which one looks more natural? > > I would greatly appreciate any help you can give me. > > Regards, > Eckhart > > > ------------------------------------------------------------------------------ > Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, > MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current > with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft > MVPs and experts. ON SALE this month only -- learn more at: > http://p.sf.net/sfu/learnmore_123012 > _______________________________________________ > Darktable-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/darktable-users > -- José Carlos García Sogo [email protected] ------------------------------------------------------------------------------ Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. ON SALE this month only -- learn more at: http://p.sf.net/sfu/learnmore_123012 _______________________________________________ Darktable-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/darktable-users
