Cryptomatte EXR Output Bit Depth should always be 32bit. #88049

New Issue

System Information
Operating system: Windows 10
Graphics card: RTX 2080

Blender Version
Broken: 2.92 release

Short description of error

I am not sure if this is considered as a bug, but as it is inconsistency in EXR file saving I report it here.

If Half Float format is selected in EXR output Cryptomatte layers are saved as 16bit , but Cryptomatte must be 32bit to be usable. This should follow same logic as Z-Depth which is always saved as 32bit even if the EXR setting is Half Float (16bit). So, Cryptomatte layers should be possible to be saved as 32bit in EXR no matter what is the main bit depth of the output file. This would be expected to avoid pipeline problems from 3D to compositing.

Attached image shows saved layer bit depths.

Exact steps for others to reproduce the error

Open attached blender_render_output_bit-depth.blend -file and render animation. File has just 1 frame animation range prepared for saving example files.
It saves 2 files to /tmp/ -folder: One from Output Properties and one from Compositor File Output
Open rendered files in image viewer that allows to see information of saved layers in EXR files (DJV).
See bit depths of saved layers in images to see that Z-Depth is 32bit in Half Float image and Cryptomatte is 16bit.

blender_render_output_bit-depth.blend

**System Information** Operating system: Windows 10 Graphics card: RTX 2080 **Blender Version** Broken: 2.92 release **Short description of error** I am not sure if this is considered as a bug, but as it is inconsistency in EXR file saving I report it here. If Half Float format is selected in EXR output Cryptomatte layers are saved as 16bit , but Cryptomatte must be 32bit to be usable. This should follow same logic as Z-Depth which is always saved as 32bit even if the EXR setting is Half Float (16bit). So, Cryptomatte layers should be possible to be saved as 32bit in EXR no matter what is the main bit depth of the output file. This would be expected to avoid pipeline problems from 3D to compositing. Attached image shows saved layer bit depths. **Exact steps for others to reproduce the error** 1) Open attached **blender_render_output_bit-depth.blend** -file and render animation. File has just 1 frame animation range prepared for saving example files. 2) It saves 2 files to /tmp/ -folder: One from Output Properties and one from Compositor File Output 3) Open rendered files in image viewer that allows to see information of saved layers in EXR files (DJV). 4) See bit depths of saved layers in images to see that Z-Depth is 32bit in Half Float image and Cryptomatte is 16bit. ![blender_render_output_bit-depth_layers_Cryptomatte.jpg](https://archive.blender.org/developer/F10054561/blender_render_output_bit-depth_layers_Cryptomatte.jpg) [blender_render_output_bit-depth.blend](https://archive.blender.org/developer/F10054563/blender_render_output_bit-depth.blend)

Added subscriber: @SakuP

#98986 was marked as duplicate of this issue

Added subscribers: @Jeroen-Bakker, @brecht, @lichtwerk

Changed status from 'Needs Triage' to: 'Needs Developer To Reproduce'

I can do the change, but would like additional confirmation from @Jeroen-Bakker and/or @brecht if this is the way to go.
(not this originally came up in #87988 (Open EXR layer bit depths differ in Output Properties and Compositor File Output))

I can do the change, but would like additional confirmation from @Jeroen-Bakker and/or @brecht if this is the way to go. (not this originally came up in #87988 (Open EXR layer bit depths differ in Output Properties and Compositor File Output))

Cryptomatte hashes can only be stored in 32 bits and with lossless compression or no compression enabled. Otherwise that are unusable.

Now that we have the metadata we can make this easier to detect. Haven’t looked at the technicalities of this but would be a good addition

Cryptomatte hashes can only be stored in 32 bits and with lossless compression or no compression enabled. Otherwise that are unusable. Now that we have the metadata we can make this easier to detect. Haven’t looked at the technicalities of this but would be a good addition

Changed status from 'Needs Developer To Reproduce' to: 'Confirmed'

I agree metadata would be better than, doing it based purely on pass names is not going to work in general.

But even that is not possible to make fully automatic, you can't always guess form the node setup if it's color or data. So every input still needs manual control I think, though it could auto detect by default for the most common cases.

I agree metadata would be better than, doing it based purely on pass names is not going to work in general. But even that is not possible to make fully automatic, you can't always guess form the node setup if it's color or data. So every input still needs manual control I think, though it could auto detect by default for the most common cases.

Think I wont have time for this, will step down since there is another patch around.

Added subscriber: @Carlosan

Added subscriber: @PierreRisch

Added subscribers: @Renderbicks, @PratikPB2123

+++ Adding important note +++

Besides 32bit Cryptomattes have to be saved losslessly. Cryptomattes will be broken and useless when saved to DWAA/B.

If a mix of DWAA/B and lossless isn't possible in a MultiLayer OpenEXR, Cryptomates must be saved separately (what Redshift is doing) in a lossless format.

**+++ Adding important note +++** Besides 32bit Cryptomattes have to be saved losslessly. Cryptomattes will be broken and useless when saved to DWAA/B. If a mix of DWAA/B and lossless isn't possible in a MultiLayer OpenEXR, Cryptomates must be saved separately (what Redshift is doing) in a lossless format.

Added subscriber: @Mots

This issue was referenced by cb9b6cefb3

This issue was referenced by cb9b6cefb3c01d3f759a16252aca59fa4607dd24

This issue was referenced by df751516e1

This issue was referenced by df751516e1f64bbc78b02582c631c3cdd0bc032d

Changed status from 'Confirmed' to: 'Resolved'

This issue was referenced by 40194f7219

This issue was referenced by 40194f72191fc629b96ce619540b3f0f5da0ccfc

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Cryptomatte EXR Output Bit Depth should always be 32bit. #88049