This is a huge problem. When exporting final renders and trying to reverse VLog (I have the appropriate stanza in conf.ocio and it’s not at fault), the resulting image loses gamut. You can best see it in darks, where a lot of details are lost. After spending the entire day - a literal 24 hours - trying to get to the bottom of it, I and a colleague, discovered that it’s GPU rendering that’s causing the problem. Something to do with float to int to float conversions not happening.
Using MANY permutations, we discovered this by placing ociocolorspace nodes after a read node and doing the reverse linear to vlog on there. Unchecking the gpu box got rid of the problem. However, put nodes in between, like chromakey and grade, and the problem comes back.
I beg you, all devleopers, please do something about this. I have to re-comp 76 shots because of this - in another software package - unless you can come you can come up with a workaround or patch. This makes Natron unuseable unless fixed. There are multiple OCIO issues, but this issue it top, top, TOP! Should be turn-key and not a giant mangle-fest. The problem revealed itself way after the inital no-op tests, which worked because no GPU colour work was involved. Please, help me save my work.