I think I’ve figured out how to correctly migrate a file from DNG Raw format to ACEScg in Nuke.
I started in Photoshop, outputting an EXR, which I brought into Nuke as a Raw image, then used OCIOColorSpace to go to ACES Interchange 2065, then to ACEScg.
Where I’m getting confused is the view transform. Working with ACEScg renders I always import them as ACEScg, then apply the ACES 1.0 SDR Video(sRGB Display) transform in the viewer.
To make this work with my converted Raw file, I needed to use an OCIODisplay node.
I set the OCIO Display node to go from scene_linear(ACEScg) to sRGB - Display with the ACES 1.0 - SDR Video view transform.
Everything looks correct in the viewer in Nuke I think. Basically the result in the Viewer roughly matches what I see when I open the Raw in Adobe Camera Raw, where it’s displaying the Raw data on my sRGB monitor.
I notice when using the OCIODisplay node, the values in my viewer jump from a max of just over 1, to up to 55 in the red channel. I assume this is the tonemapping - it’s displaying what was an ACEScg value in sRGB, a far smaller colorspace.
The problem then is when I use a Write node. I set output to color_picking(sRGB), which is what I’ve always done for ACEScg renders with the view transform baked in(ie a render saved from the VRay framebuffer).
But when doing this it results in very clamped looking highlights. Which is sort of expected due to the high values, but I’m not clear what I need to do to export correctly.
I documented my process here: Testing OpenColorIO and ACES Raw Conversion: Part 1 — alex corll
Any thoughts on what I’m doing wrong with the OCIODisplay node or my output? The goal is write out an sRGB png that matches what I’m seeing in the Nuke Viewer.