ICC to 3D LUT

[Megalith]

Anyone know if it's possible to convert an ICC profile to a 3D LUT? I did a little search and it seems like the opposite is possible, so I'm hoping it goes both ways.

 

[bmg]

Anyone know if it's possible to convert an ICC profile to a 3D LUT? I did a little search and it seems like the opposite is possible, so I'm hoping it goes both ways.

No, 3D LUT is included in the icc profile, but the icc profile includes much more information that just the LUT.

ETA: Hm, just reread your post....I don't know where you're getting the idea that you can get the icc from just the LUT, but you have it backwards. You can extract the LUT from an icm file with a hex editor, which I've done before, but an easier way is to use CPKeeper.

 

[Megalith]

Thanks, I went ahead and downloaded CPKeeper. But how do you use it to extract an LUT? It seems like the only thing it'll let me do is force color profiles.

 

[bmg]

Click on the "..." on the right side, select the icm file you want and click apply. That will load the graphic's card LUT with the one from the icm file. Now click the "*" on the left side and save the file. That's your LUT with 3 bytes for "CPK" added at the front. If you want the file without those you can delete them with a hex editor and save. CPKeeper is a great tool, so depending on what you want to do, you might want to just keep the LUT in the .cpk format.

You can also load the LUT using CPKeeper as I mentioned, or it might already be loaded if you have the icm file set as default. Then run VideoEqualizer, which lets you look at the LUT and tweak it, then save the file and get the LUT. I use VideoEqualizer to directly create my desired LUT file, along with HCFR to measure, and CPKeeper to try to lock the LUT. Works very well.

 

[Sailor_Moon]

No, 3D LUT is included in the icc profile, but the icc profile includes much more information that just the LUT.

The proprietary vcgt only contains 2D-LUT information. When talking about display profiles we must distinguish between matrix and LUT profiles. The latter contain 3D CLUTs for transformations from and to the PCS with different intents.

Anyone know if it's possible to convert an ICC profile to a 3D LUT?

What do you want to achieve? If a RGB to RGB transformation is intended you need to specify a source and a target characteristic which are used by a CMM to calculate the supporting points for an accordant CLUT. The color space emulations of some prosumer/ high-end screens work in this way (example). Light Illusion should offer a solution for creating such an 3D-LUT – but I think also Argyll, at least for RGB source and target profiles (not sure if device link profiles are supported). Or do you only want to extract the 2D-LUT vcgt information which is intended to linearize the display in a software calibration workflow?

 

[bmg]

Very good info Sailor_Moon.

 

[Megalith]

I simply need a 3D LUT to load into MadVR.

I calibrated with a Spyder 4 and have a proper ICC, but supposedly calibration doesn't extend into video playback.

 

[Meeho]

Isn't ICC 3x 1D LUTs, not 3D LUT?

 

[Sailor_Moon]

Isn't ICC 3x 1D LUTs, not 3D LUT?

See #5: 2D-LUT was a bit misleading: The vcgt contains 1D information for linearization tasks. But that is not the main content of an ICC profile and doesn't enable color space transformations. A LUT profile therefore contains 3D CLUTs for transformations from and to the PCS while a matrix profile describes the actual display characteristic via a simple 3x3 matrix and the trc per channel.

I calibrated with a Spyder 4 and have a proper ICC, but supposedly calibration doesn't extend into video playback.

At least the MPC HC can internally create a 3D-LUT on basis of display profile and desired target characteristic. For a dedicated RGB to RGB 3D-LUT you should study the functionality of Argyll.

 

[umeng2002]

MPC HC with madVR. MadVR allows the use of a 3D-LUT. Use google to find out how to create a 3D Lut if your calibration software doesn't have this feature..