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Discussion Starter · #1 ·
Hi,

I'm having an issue with calibrating my LED Samsung display (SyncMaster P2250) with dispcalGUI.
I'm using i1 Display Pro colorimeter.

When I verify the results in HCFR grayscale and gamma is really good.
But for some reason the colors are way off.

Please check the attached screenshots.

I noticed that dispcalGUI is using many grayscale patches when calibrating but only few colored ones.
Maybe I need to use some other testchart...

Does anybody have an idea what I'm doing wrong?

Thank you.
 

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In order to do color correction (gamut mapping) of video sources you'll need to run a 3dlut using either software like MPC-HC/madVR as your player or external hardware like the eeColor box.
 

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Discussion Starter · #3 ·
Oh I see... but if I create 3dlut it will be applied only to the madVR I guess. I'd like to have correct colors system-wide (in all applications).
 

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Hi all,

I'm very newbie when it comes to ArgyllCMS, I'm learning so my apologies for asking silly questions.
My first experience with ArgyllCMS is by running DispcalGUI on a projector, with good results I'd say.

My first silly question is: why I need MPC-HC to apply a 3dlut correction? What is the difference between doing it through the OS?

Thank you!
Tony
 

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I don't think windows supports 3dLUTs. The only way you can implement 3dLUTs is through applications that support them, such as MadVR.
 

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A popular option is to adjust the display to meet grayscale and gamma targets, through the OSD, until you can't do any better, and then use your software of choice to generate a set of 1D LUTS which are loaded into the GPU LUT, and will workwork system wide (unless an application overrites the GPU LUT). These 1D LUTS can help fine tune grayscale and gamma.
 

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Ok, so the OS can only do a 1D lut, which is only calibrating gamma and grayscale. While a 3D lut can also do colour correction. Got it, that's why my gamut was never right, thanks.
 

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Ok, so the OS can only do a 1D lut, which is only calibrating gamma and grayscale. While a 3D lut can also do colour correction. Got it, that's why my gamut was never right, thanks.
Most Operating Systems (OS) support ICC profiles, which are much more flexible than a Video calibration.

Typically for software application use, you would calibrate the display (ie. by using 1D luts in the form of the 'vcgt' tag in a display ICC profile) to choose a brightness, white point and light response curve so that non-color managed applications will look OK, and then you would profile it as an ICC device profile and then install the profile in the OS. That way color managed applications know what the profile is for that display, and can then use the profile to convert colors into the correct RGB for that display. In this way the application can process any color in any colorspace it understands. Typically it understands what other colorspaces are using ICC device profiles. So the overall process a color managed application uses is to interpret an incoming color using one ICC profile and then convert it to the display RGB using the display ICC profile. This typically uses the CMM (Color Management Module) provided by the OS, but some applications use their own (ie. Adobe use ACE, ArgyllCMS has its own, lcms is used widely).

By comparison typical Video calibration is much simpler and less flexible. The source colorspace is assumed to be Rec709 + BT.1886, and either the display itself is adjusted so as to try and reproduce that colorspace, or a 3D lut (equivalent to a ICC device link) can be used to transform directly from the Video RGB space to the displays RGB space.
 

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Discussion Starter · #10 ·
Hi,

After longer time I tried to calibrate my display again and create an ICC profile.
I generated profile with dispcalGUI, installed it on Windows and tried to use it with Firefox and GIMP.
Both of these programs support ICC and I could see it is working (verified with HCFR), but for some reason the colors are too off (again, but different way).
Blue is completely undersaturated which can be easily seen on pictures.
DispcalGUI report says that blue has deltaE 8.38!

I used Large testchart for LUT profiles, optimized for Gamma 2.2 with REC.709 primaries (D65).
Maybe I should use some other testchart.
Maybe my cheap display can't be calibrated more precisely... I don't know.

Please check the attached screenshots.
If anybody has an idea what might be wrong please let me know.

Thank you.
 

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