Hi, i´ve been looking for info about HDR workflow in UE4 and the only documentation is this:
But with that info i cannot make it work. It gives you a few commands and that´s all. It doesn´t explain how to visualize it properly, or how to export to another software like DaVinci Resolve. Or if we have to do something different with the lighting on the scene.
Here i only found a couple of people asking for the same thing but with no replies or no good info. And if i look for it in Google is all about HDRI, not HDR visualization.
Is it possible to contact some of the developers to ask them about it?
A guy learned to me we can export in .exr 16bits in Movie Render Queue,
And add the setting “Color Output”, enable OCIO in it, and create a config source and choose “Rec.2100-PQ (HDR Video)” as a “Transform Destination” for example.
But my .EXR outputs images are very flat, like a log image from camera, no HDR curves when I watch it in Photoshop’s “Camera Raw”.
So yes, it would be nice to have more information about rendering HDR sequences correctly.
(↑This is an SDR screenshot to avoid over-exposure. For anyone trying this, turn on HDR display in both Davinci Resolve and Windows, and your frame will brighten up)
The reason for EXRs looking “flat” is because there are no metadata indicating its color space. Davinci Resolve (and other software) may treat it as Rec.709 by default.
By manually assign Rec.2100 ST2084(PQ), the image will recover a better look. Btw I also notice that there are still some differences between the color-transfered image and Unreal viewport. To correct the color, you can try a simple adjustment like this:
An alternative is to make a post process material in Unreal, power the scene color by around 0.85 (magic numbers, idk why, looking for explanation), then the exr output will look almost the same as viewport under Rec.2100 PQ color space.
Anyway this is not a standard workflow - professionals may use linear Rec.709 or ACEScg, rather than output a hardcoded Rec2100 PQ image. By doing so, we can easily transform the original image to other color spaces (SDR/HDR) during video editing.
