IS:

Are you using GC shaders with IDL? I haven't tested extensively, but I think you really can't. The data that GC shaders reutrn is for how to make that luminance on a screen. For light measurement purposes, those numbers are way too high. That would cause over-exposure for sure. That's why linear rendering is so important.

With Poser 8 and IDL, dump GC shaders altogether. Use linear output only from shaders. Make sure all diffuse calculations throw less light than arrives (Diffuse_Value < 1). Use HSV Exponential Tone Mapping at 2.2 for the final adjustment (approximately) to sRGB color space.

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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)