It seems to me that some aspects of the rendering aren't being properly handled in terms of linear and gamma spaces. There are multiple clues of this, but a prominent example is how the bloom effect of stars has a mismatch with the body color. If the in-game gamma slider is turned up to 2, this effect is reduced and looks more like it should. Here is an example of the solar system with disabled diffraction spikes and the "exposure" tone mapper to demonstrate the point. A reddish halo around the sun is rather prominent by default. The higher gamma setting extends the bloom, but importantly, the hue stays rather consistent.
Gamma = 1
Gamma = 2
In addition to this, the shading contour of the moon is also affected by the gamma shift. If you ask me, the gamma setting of 2 more closely resembles this educational slide on gamma-correction.
Source: Uncharted 2 HDR presentation by Hable
There is even a demonstration that uses the real moon as a reference.
Source:
https://project-eden.blogspot.com/2011/ ... nated.html
A gamma setting of 2 is roughly equivalent to an sRGB EOTF that is being performed in order to apply gamma-correction.
