On Mon, Feb 4, 2013 at 9:46 PM, Richard Levitte <[email protected]> wrote: > In message > <CANqV4tVGpe0zqg4K1=shvvztah1z7sq4qhsoe7x1q6f3iqm...@mail.gmail.com> on Mon, > 4 Feb 2013 19:19:45 +0100, Pascal de Bruijn <[email protected]> said: > > pmjdebruijn> Double correction cannot happen (well unless you have a really > highend > pmjdebruijn> LaCie/EIZO display which can do hardware correction or > something). > > Ok, in that case I'd like an explanation to what's happening to me. > This all started with me color characterising my monitor (laptop LCD) > and creating a profile for it (using dispcalGUI), then loading it > (using 'dispwin -L'). Display colors became much better (grey is > actually grey, not something with a blue tint). > > Then I started doing some work on some images I had taken just > recently, and what I got was absolutely h-o-r-r-i-b-l-e. Basically, > the three channels were kind of shifted in the histogram, and what was > supposed to be a black background was now redish brown or some such. > (I wonder if I could possibly produce a test, say by putting together > a white .png, import it and see how it ends up). > Changing my display profile from "system display" to "sRGB" gave me a > better look.
Sounds like an invalid profile? Did you use GNOME Color Manager to generate it? Which type of colorimeter did you use? Do keep in mind that low end devices tend to be prone to get invalid reading on some display types, particular with newer LED displays. > pmjdebruijn> I have further details on anatomy of display profiles here: > pmjdebruijn> > pmjdebruijn> http://blog.pcode.nl/2012/01/29/color-management-on-linux/ > pmjdebruijn> > pmjdebruijn> If you still have any questions left, feel free to give me a > bump. > > Yup, I've read it and it makes a lot of sense. What doesn't make > sense to me is why there's a need for a program like Gimp and > darktable to use the display profile to correct colors that are > corrected through the VLUT (by the X11 driver, I assume)... It's not the same thing. Think of cooking, if you make something that needs to be more salty and sweet, only adding the salt won't do the trick. You need to add salt _and_ sugar. (sorry for the horrible analogy :) The VCGT corrects for whitepoint and gamma. The matrix characterizes the displays gamut (which possibly means shifting hue's and scaling saturation). And mapping input gamuts to display gamuts can be a dynamic process when using the (for example) commonly used perceptual rendering intent. And the VLUT is inherently static. Regards, Pascal de Bruijn ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_jan _______________________________________________ Darktable-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/darktable-users
