You have to understand that over-bright lights represent one (indirect) approach to gamma *compensation*. Gamma *correction* is a direct approach. If you combine compensation with correction, you get overcompensation.

Another common compensation is found in shaders. For example, many have screwy settings to produce what looks like a decent skin, but when GC is turned on, they produce ugliness. A typical one is that specular highlights are made broader than they should be, because they appear to fade out too quickly. But with GC, they don't, and end up producing exactly what we see in your GC render. The highlights smear out and they make everything look washed out.

So in addition to turning lights down, you have to stop using messed up shaders.

And it isn't as though setting up a couple lights for a portrait is hard. Here are two spotlights. On the left it is white at 75% intensity. On the right it is white at 30% intensity. I rendered with GC and IDL. This looks great to me.

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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)