Cycles Standalone stange behavior

I started to experiment with the standalone Cycles from the repository head. It says version 3.2.0. I have a very simple scene where I would like to see the effect of sky texture. In particular lighting the tall box properly and casting shadow on the ground plane. I noticed several issues, perhaps related to other questions here that remained unanswered (linked below).

  1. Having a simple <background color="1 1 1"/> I would expect the background to be white, i.e. rgb(255, 255, 255). That is not the case, it is rbg(204, 204, 204). I assume there is a filmic transform enabled somewhere, but I didn’t find any attribute of any xml node for setting the transform. Is there a way to control it? I assume this is related to this question.


    color_background.xml (4.9 KB)

  2. If I attach a <sky_texture> in front of the background passing its color, everything is suddenly overexposed. When I tried the same action in Blender GUI, it did not result in any overburn. What is going on in Blender on top of Cycles? This is most likely related to this question. I managed to mitigate by setting <film exposure="0.25"/> but I am not happy about that since I assume it is an ad hoc hack, not a systematic solution.
    sky_background.xml (5.2 KB)

  3. So having the shorter exposure avoids overburn, but there are now many fireflies. Why that? There are no glossy materials in the scene. Everything is just perfectly diffuse. Did I miss something in the settings?
    sky_shortexposure.xml (5.2 KB)

  4. The strangest thing happened when I tried to wash away the flies by enabling the denoiser <integrator use_denoise="true">. All of a sudden, I got an overexposed image again. Despite the shortened exposure. That is for sure not an indended behavior of a denoiser. What is happening there?
    sky_skortexposure_denoised.xml (5.2 KB)

How can I get a reasonable behavior of the sky texture and proper color management?

Note that for running all test files you will need to place the following file b.xml into a subfolder called p:
b.xml (198 Bytes)