Quote - pardon, but i'm still wondering about how we can use the new equation if you basically said it's wrong to not anti-correct images on input, and that we should preserve the hue and saturation shift, since you seemed to be saying that the new equation didn't do the latter and definitively said it didn't do the former.  also, i'm still wondering if you're saying IBL just doesn't work for any scene with flat surfaces.

I said it's wrong to not anti-correct images on input for GC. I didn't say that in the context of HSV Exponential Tone Mapping. I said the opposite - that HSVETM affords the possibility of getting decent luminance shifting while preserving hue and saturation, without having to anti-GC the incoming material. It is a way of converting linear to approximately sRGB entirely as a post-processing step. It is not based on the physics of light, nor on the mathematics of CG. It was developed in the context of manipulating HDR images.

Quoting myself here:

"Right! But it doesn't have that rapid rise from 0 that cobaltdream doesn't like. That's what causes terminators to look too sharp.

Also, while the curves are similar, this preserves hue and saturation! So you don't need to anti-gamma first. It kind of figures out what you'd get if you had done ant-gamma first, and produces similar results without doing so."

"By the way, the technique is similar to (or maybe exactly the same as) the tone mapping technique called HSV Exponential Tone Mapping or something like that. I can't find any clear CG-community approved exact mathematical definitions. I can only find verbal descriptions of these techniques in other products, like VRay and Kerkythea. In all cases they talk about adjusting luminance while preserving hue and saturation. It is from those little clues and the words HSV and Exponential that I guessed at how to do it."

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)