Poser's gamma correction is the simplified version, so it isn't even accurate sRGB conversion, technically. GC 2.2 and sRGB are only slightly different in bright colors, but very different in very dark colors.

As far as gamut goes, Poser calculates lighting and shading effects as linear, unbounded values, so there is not a problem with out-of-gamut values during calculation.

The final output, however, is clipped to 0..1 and either spit out as linear (which most people use and don't know how awful it is) or GC.

I have shown often how to do true sRGB in and out using shaders. More work, yes, but if that's what you want then that's what it takes.

It is also possible to perform any sort of output correction in Poser using my "artistic lens" prop. This is just a straight Refractor, IOR=1, mounted on a square. In its shader, the Refract node samples the scene and gives a linear value - which you can then manipulate to any color space you want.

You could also just post-work convert, although to avoid problems you'd want to work in EXR format, not JPG or similar.

Let's talk more about this. I'd like to hear more about what you're trying to do.

 

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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)