Am Sonntag, 10. Februar 2013, 11:03:46 schrub S. Witt: > Hi list, Hi user,
warning: long explanation ahead. > yet another question regarding the screen profile;-) > DT loads the screen profile automatically, which is totally fine for me. > Nevertheless I wonder if I could find some messages or feedback, > regarding the success of this operation or the actual source, from where > DT received the profile (X or colord). If you are using git master you can now start darktable with "-d control" to see where darktable gets its profile from. > I created my screen profile on the command line using argyllcms. First I > used the KDE equivalent of GCM to set the profile and probing the > ICC_PROFILE atom, using > xprop -root | grep ICC_PROFILE > seem to be fine. Also a colord process is running. The colors of the > display shift visibly, when loading the profile. > > However, just for fun, I copied the screen profile in > ~/.config/darktable/color/out > so that I could set the profile manually in the iop for the output > profile. Doing this, I expected that nothing changes, but the colors > shifted visibly. > So it seems to me that darktable either retrieves no profile or a > different one from X or colrod!? > Maybe you have some hints how to make some reasonable diagnostics? Ok, let me shed some light on how we load display profiles since that seems to confuse a few people: The function responsible is dt_ctl_set_display_profile() in src/control/control.c. It gets called on startup of dt as well as when the window is moved, resized or when the size of the center widget (where the image is displayed) changes, for example when collapsing side panels. Basically whenever the bigger part of the displayed image could have moved to another screen. In this function we are trying to get a profile from the system (xatom on Linux, some api calls on OSX/Windows). If the profile changed since the last time a signal is raised so stuff gets updated. In case that dt was compiled for Linux and with colord support there is also a request sent to colord for the screen profile. However, this is done asynchronously, we do not wait for the response. Once colord told us about the profile we do the same checks as before (is it a different profile than what we are already using?) and eventually update the profile and raise the signal, again. To make a long story short, when you have the xatom set you should always see that one being used since the colord response should come in too late to be considered. When no xatom is set you should get the profile from colord. BUT: In case you have different profiles in the xatom and colord strange things will happen – dt will use the xatom profile just to replace it with the one from colord a few milliseconds later. > BTW: I also tried this under gonme 3, using GCM to set the profile. The > result is the same. Trying something similar in gimp, worked fine and as > expected: Colors shift slightly, when switching on color correction and > there seems to be no visible difference between a manually set screen > profile or the automatically retrieved one. > > Thanks and regards > Sören Tobias
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