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Cryptomatte affected by Color Space change in OpenEXR multilayer.
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Description

System Information
Operating system: Windows-10-10.0.17134 64 Bits
Graphics card: Intel(R) HD Graphics 4000 Intel 4.0.0 - Build 10.18.10.5069

Blender Version
Broken: version: 2.80 (sub 75), branch: master, commit date: 2019-07-29 14:47, hash: rBf6cb5f54494e
(also tried on the latest 2.81 Beta)
Worked: (optional)

Short description of error
I don't think it's a bug, but rather something that hasn't been thought of. Currently when you use Cryptomatte and export an OpenEXR Multilayer file, if you then import it into the compositor and change its color space to something other than linear, the cryptomatte passes will also be affected by the color space change and will no longer work properly.

Cryptomatte color picking with linear color space :

Cryptomatte color picking with linearACES color space :

Here is an example .blend with an EXR Multilayer file packed into it :

Exact steps for others to reproduce the error
Download the example file.
First set the image in linear color space.
With the cryptomatte node, pick the color of the chair for example as in this image :

Then show the generated mask of the cryptomatte node :

In linear color space, everything works as expected, the cryptomatte node masks only the chairs.
Then, set the image color space in linearACES for example.
(you'll notice that the color picking output of the cryptomatte node isn't displayed the same way as in linear color space)
Delete the values in the cryptomatte node.
Pick the color of the chairs like the first time.

Then show the generated mask of the cryptomatte node :

The mask does not only include the chairs as expected but also other objects, and the edges of the mask are too sharp compared to the same mask in linear color space.

Details

Type
Bug

Event Timeline

sineo (sineo) updated the task description. (Show Details)Sun, Aug 4, 9:39 PM
Sybren A. Stüvel (sybren) triaged this task as Needs Information from User priority.

Please attach a minimal blend file with the required EXR file(s).

sineo (sineo) updated the task description. (Show Details)Tue, Aug 6, 8:48 PM

I can confirm that the look of the cryptomatte in the compositor background changes when you change the Color Space setting of the EXR image node, including seeing edges:

However, I can't confirm a change in behaviour when picking objects via the Cryptomatte node.
Please describe the steps to reproduce in a way that we can literally follow, and clearly describe your expectations. Example "when clicking on this object (include a screenshot with an arrow where to click) the selected value should be X but when I set the Color Space to LinearACES it is Y". That makes things easier to confirm than "it behaves very weirdly".

sineo (sineo) updated the task description. (Show Details)Fri, Aug 9, 8:00 PM