Michael314 opened this issue on Aug 09, 2009 · 32 posts
bagginsbill posted Thu, 24 December 2009 at 8:43 AM
Tone mapping is not to replace GC. I have shown how to abuse it to get something better than nothing, but it isn't GC. The purpose of TM is to transform values (potentially infinite values) into the unit-range 0 to 1 which is all that can be displayed on a computer monitor or piece of paper.
In so doing, it happens to make anything that starts in the unit-domain 0 to 1 curve upward, sort of like the GC curve does. But it isn't the same curve, and GC can go above 1 outside the unit-domain, but TM cannot.
The equation for GC (for gamma=k)
x ^ (1 / k)
The equation for TM (for arbitrary exponent, k)
1 - e ^ (-kx)
I'm using the "^" symbol for exponentiation. In the TM, e is the magical mathematical constant e, 2.71828... . But in this case, the value of e as a base is not important as it is possible to change to any other base value as long as we also make a corresponding adjustment in k, which itself is an arbitrary meaningless value. Put another way, no matter what base we change to, the new function is isomorphic with the original. But the GC and TM curves are not isomorphs - they do different things, even though at first glance they appear to have the same general shape, at least in the unit-domain.
As for why only Pro has it? It was a marketing decision. There is no technical barrier. In fact, it complicates things a bit to have any differences between Pro and regular Poser. Maintaining two different versions of the same code base is more complicated than maintaining only one version.
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)