Gamma 2.2 with Don't affect colors (adaptation only)

[rmejia]

Here are three images:
link

The first one has the Color Mapping Gamma set to 1, the second one has the Gamma set to 2.2, the third one has the "Don't affect colors (adaptation only)" box checked with gamma set to 2.2

The one with the gamma 2.2 with the "Don't affect colors (adaptation only)" activated has "blowouts" occurring in object close to white colors, under sunlight. There is no white 255 in the scene, the whitest color has a value of no more than 245. I assumed that the don't affect colors affected only dark areas giving more definition to areas in shadow. Is there any reason that it is blowing up materials close to color white? Are there some limitation to using the "Don't affect colors (adaptation only)" check box?

[vlado]

Do you have other color mapping in addition to the gamma value? The "Don't affect colors" option causes V-Ray to ignore all color mapping, not just the gamma.

Best regards,
Vlado

[rmejia]

Ah! I see now how it works... I did have the Burn Value set lower, at .5 using Reinhard, did a test with the don't affect colors and it came out like a render with the Burn value set at 1.0

I checked out the help section and found this:
Don't affect colors (adaptation only) - when this parameter is on, the color mapping will not be applied to the final image, however V-Ray will proceed with all its calculations as though color mapping is applied (e.g. the noise levels will be corrected accordingly). This can be useful, for example, if you know that you will apply some color correction to the image later on, but wish to keep the rendering itself in linear space for compositing purposes. Note that the Clamp output option will have an effect regardless of the value of the Don't affect colors option.

[JeffG2]

Unless I'm nuts, the "adaptation only" renderings have better and richer colors than the straight LWF images.

I just started using "adaptation only" with the gamma set to 2.2 and the srgb button on in the VrFb and I am much more pleased with the images I'm getting now then I have been with the old LWF method.I'm finally able to get the dark shadows and rich lighting I was missing in my LWF images.

Edit: I see now that "adaptation only" basically means "no gamma correction" and therefore my improved image must be coming from the srgb display option.... or not???

[^Lele^]

Think of "adaptation only" as a way to aid the AA phase in the darker (less contrasty) areas.
It comes in particularly handy when the image is saved linearly (exr), but will have to be displayed with a 2.2 gamma, for instance.
Without "adaptation only", when displayed at 2.2 gamma, the noise in the darkest areas would be very visible.
Making vray antialias the pixels after the 2.2 gamma is applied, before remapping them back to linear, helps avoiding that issue.
Notice the max gamma is for DISPLAY ONLY, so the vray color mapping controls have to be used instead.