What is the Corona Cryptomatte?
The Corona Cryptomatte is a render pass that will help you easily create color mattes of a complex scene with hundreds of objects.
It uses three methods to automatically generate the render channels stored in a multichannel OpenEXR file which removes the hassle of creating dozens or hundreds of single masking elements.
To extract the mattes from still images you need to use specialized software. One example is the free Exr-IO plugin for Photoshop (you can download it here). Without the plugin, Photoshop won't be able to extract the Cryptomatte data correctly.
Currently, to use the Cryptomatte element properly, you must save the element in the .CXR file format from the Corona VFB, rename it to change its extension to .EXR and then load it in your preferred compositing software.
Example of the "Beauty" render image.
This is what the Cryptomatte pass looks like when rendered.
Note: what you see in the VFB is just a preview. It is not an accurate representation of the data included in the Cryptomatte element. Some visual artifacts may appear (e.g. when using motion blur and DOF), and the colors may not appear to be distributed correctly, but this does not affect the usability of the element in post-production.
How to use the Corona Cryptomatte?
To start using the Corona Cryptomatte, simply go through the following steps:
- Open the Corona Multi-pass window. You can find it in the menu Corona > Multi-pass...
- Then make sure to enable the active passes by activating the "Enbl" checkbox.
- Next, from the "Available passes" section on the left, open the category "Mask", and drag the Cryptomatte pass and drop it into the "Active passes" section in the middle.
(alternatively, you can use the little right arrow button located between the sections mentioned above to add the Cryptomatte pass)
The Corona Cryptomatte parameters
You can adjust the Cryptomatte's behavior by modifying its parameters.
The ID type
This parameter determines how many objects are distinguished in the Cryptomatte pass.
You can set it to work using any of the three available modes.
ID type: Name
Using this mode, only objects with the same name will have the same color. This means that if all of your scene objects have different names, different colors will be assigned to each one of them.
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| In this example, the ID type is set to "Name" | In this example, each object has a different name. |
This is the resulting Cryptomatte pass when the ID type is set to "Name"
ID type: Name with hierarchy
Using this mode, only objects with the same name and in the same group hierarchy in the object manager will have the same color.
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| In this example, the ID type is set to "Name with hierarchy" | In this example, objects in the same group have the same name. |
This is the resulting Cryptomatte pass when the ID type is set to "Name with hierarchy"
ID type: Layer
Using this mode, only objects in the same layer will have the same color.
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| In this example, the Id type is set to "Layer" | In this example, the objects have been assigned to different layers. |
This is the resulting Cryptomatte pass when the ID type is set to "Layer"
Maximum object levels
This parameter determines how many different objects can be identified by the Cryptomatte in a single pixel. By default, this value is set to 6.
Notes:
- What you see in the VFB is just a preview. It is not an accurate representation of the data included in the Cryptomatte element. Some visual artifacts may appear (e.g. when using motion blur and DOF), and the colors may not appear to be distributed correctly, but this does not affect the usability of the element in post-production.
- Currently, to use the Cryptomatte element properly, you must save the element in the .CXR file format from the Corona VFB, rename it to change its extension to .EXR and then load it in your preferred compositing software.