Exposure parameter in CIE affects RGB masks

[DPS]

Took me a while to figure this one out - I thought I had some gamma issues with the masks having incorrect gamma. Turns out that the behaviour use CIE is different to the frame buffer.

This makes it really difficult to submit jobs to backburner. I was hoping I could save to CXR and then tweak the lightmix, and then save out 16bit tiffs.

[TomG]

Just to confirm, using the latest build, the CIE tone mapping does affect render elements, for example a CTex pass with AO in it. Adjust the tone mapping in the Max VFB, and it leaves the AO unchanged. But load the CXR into the CIE, and adjust the tone mapping, and it also adjusts the AO pass.