Corona 5's skew towards red in overexposed scenes (incl. 3dsmax scene file)

[SharpEars]

The detailed explanation is up to our developers, since I lack the knowledge to explain it. I have logged this "issue" as (Internal ID=426329039) and will share the explanation here as soon as it is provided.
Meanwhile, you can use the "notify" button at the top of this page to be notified by email about any updates in this thread.

OK, great, and just as a last question, could you please tell me what you did to get the correct image in your prior e-mail. The image where the lights gradually transitioned from blue to cyan as they were expected to?

I am referring to this image which has the colors, more or less, that I expected the scene to produce given the materials and lights in said scene:

[maru]

To get that "correct" color grading, I used "Kim Amland Photographic 1" LUT in the VFB.

[maru]

Ok, so here is a programmer explanation for non-programmers:



- The diagram is showing the sRGB color space (the smaller triangle) inside the wide RGB color space (the larger triangle). The wide RGB color space contains the sRGB color space (some color values overlap).
- Originally, we have the blue color which is the corner of the wide RGB chromatic diagram.
- Such color is outside of sRGB.
- In order to convert it to sRGB we have to move the color inside the sRGB diagram, which we do using some transform.
- One way to do it is to move it along the line connecting white color (black dot) with the original color, until we are inside the sRGB diagram. This can change the color hue (as seen in the diagram).

There are different algorithms to map from the wider gamut to the smaller gamut, we may investigate them in the future and see if some work better.

[maru]

(Internal ID=430553805)

[maru]

Our ACES OT operator in the new tone mapping should mitigate this effect (it is also enabled by default in V9 daily builds).
Other than that, I don't think we can expect any changes in this behavior.