Fully agree with that, I wrote the distinction between Integer and Half-float Tiff above, like three times :- ).
And that is imho the issue with the Rhodesy's current workflow. If you write data into integer Tiff with gamma 1.0, it's baked down, and you loose the range in blacks.
Try this quick experiment to prove it: Change your gamma (in 8 or 16bit mode in PS) to 0.454 (to simulate writing it to 1.0), bake it down, and then bring it back to 2.2. The result will be slightly wrong, noticeably in blacks.
This will not happen in PS's 32bit mode with either 16 or 32bit .exr/.hdr files.
Njen is right that compositing softwares, heck, even Adobe AfterEffects offer you the option of linear compositing regardless of whether you're in 8/16/32bit depth mode. In AE, you even have check-box to blend colors linearly in sRGB environment, and vice-versa (and you can interpret each pass/layer as sRGB/linear individually).
But Photoshop is strict and doesn't offer this distinction. 8/16bit mode in PS is clamped, output-referred workflow and 32bit is linear, scene-referred workflow.
Looking at the posted examples, almost all results look wrong to me. I get some feeling you're abusing compositing workflow to get artistic effect. Basically working out-of-the-box and that is completely fine, people get fantastic results with all sort of strange workflow they invented :- ). But the point of LinearAdd in compositing is the exact math of recreating how the passes add up in renderer for physically correct result. It's not to provide any gradients or range for artistic purpose. All the images seem to lack any form of tonemapping and feature oversaturated overblown highlights.
Photography retouchers don't work in linear and they can get any effect they want.
Look at my quick (300perc. boosted in size) example. The left is original 2.2 16bit Tiff. The right is one which was converted to gamma 1.0 and taken back to 2.2. (this should be identical as writing it to 1.0 directly)
« Last Edit: 2018-11-09, 10:15:02 by Juraj Talcik »
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