Following up on the discussion at today’s CLF VWG meeting, I’ve created an example test for the Preview Tier.
These may be found on the CLF Implementation DropBox Paper home page:
In summary, there is a source image, a CLF, and a result image as follows:
- source image: CLF_testImagePrototype_v005_acescct.dpx
- aim result image: CLF_testImagePrototype_v005_rec709.dpx
- test CLF file: acescct_to_rec709.clf
The proposed tolerance for this simple test is +/- two 10-bit code values.
Here is some more detail regarding how I created these:
I created the CLF by using OCIO to bake a transform from ACEScct to the Rec.709 ACES Output Transform into a simple 33x33x33 LUT3D. The steps I used are as follows:
Download and build the OCIO master branch from source on GitHub.
Download an ACES OCIO config and set your OCIO environment variable to point to the config file.
Use the OCIO command-line tool ociobakelut to bake the CLF using the following command:
ociobakelut --inputspace acescct --outputspace out_rec709 --cubesize 33 --format "Academy/ASC Common LUT Format" --v acescct_to_rec709.clf
(Note that I used the ACES OCIO 1.0.3 config for this test, because it was easier, although the 1.1 config would be slightly better. In any case, this is just a test and for the real test suite we will use a config that is based on OCIO v2 which will be more accurate.)
I edited the CLF in a text editor to add some metadata to the header and add the tetrahedral attribute to the LUT3D.
I’m uploading a version of Alex Fry’s CLF test target that I processed from ACES2065-1 to ACEScct and saved as an 10-bit DPX file. This would be the source image for the test. (I was going to use ocioconvert for this, but for reasons that are probably not worth elaborating on, I used another approach.)
Use the OCIO command-line tool ocioconvert to apply the baked CLF to the source image using the following command:
ocioconvert --lut acescct_to_rec709.clf CLF_testImagePrototype_v005_acescct.dpx CLF_testImagePrototype_v005_rec709.dpx