Chaos Corona for 3ds Max > [Max] Daily Builds
Cryptomatte playground!
TomG:
Unlike other masks, which use a "puzzle matte" approach of a single layer with different colors in them to denote different objects, materials, etc., Cryptomatte places the mask for each item in its own separate layer in the file (the CXR, which you can rename to EXR). The layers will be named after each object, or layer (in the host application), or name and layer, etc. as determined by what options you checked in the cryptomatte render element, and will contain a greyscale mask for that object (or layer, or etc. depending on what you checked in the cryptomatte settings). The fact this color map type layer exists is just a side effect of the calculations, and is not the actual cryptomatte data in usable form, and can be ignored (and deleted, even, once in Photoshop).
To see these layers, the application you use to load it MUST understand cryptomatte data, otherwise you won't see them. For Photoshop, this would mean using Exr-IO, which in the latest version can read and translate cryptomatte data. There is other software out there that has a native understanding of cryptomatte, such as Nuke, but I don't have that so can't comment on the workflow :)
You can check tutorials like https://youtu.be/apk11RaFKo8?t=247 as an example (also see the 5 minute 40 second mark, where they copy and paste the cryptomatte mask for an object into the mask for an adjustment layer, which is how you use it to refine, say, exposure for a particular object, or color tint, or saturation, or whatever adjustment layer you are using).
Hope that helps! Naturally when time allows, we'll be making our own tutorials going through from start to finish too :)
TomG:
PS, as noted at the start of this thread, CXR is the ONLY file format that can save cryptomatte data from Corona at the moment, so you must save to that.
romullus:
--- Quote from: TomG on 2022-02-11, 04:05:05 ---Unlike other masks, which use a "puzzle matte" approach of a single layer with different colors in them to denote different objects, materials, etc., Cryptomatte places the mask for each item in its own separate layer in the file (the CXR, which you can rename to EXR). The layers will be named after each object, or layer (in the host application), or name and layer, etc. as determined by what options you checked in the cryptomatte render element, and will contain a greyscale mask for that object (or layer, or etc. depending on what you checked in the cryptomatte settings). The fact this color map type layer exists is just a side effect of the calculations, and is not the actual cryptomatte data in usable form, and can be ignored (and deleted, even, once in Photoshop).
To see these layers, the application you use to load it MUST understand cryptomatte data, otherwise you won't see them. For Photoshop, this would mean using Exr-IO, which in the latest version can read and translate cryptomatte data. There is other software out there that has a native understanding of cryptomatte, such as Nuke, but I don't have that so can't comment on the workflow :)
You can check tutorials like https://youtu.be/apk11RaFKo8?t=247 as an example (also see the 5 minute 40 second mark, where they copy and paste the cryptomatte mask for an object into the mask for an adjustment layer, which is how you use it to refine, say, exposure for a particular object, or color tint, or saturation, or whatever adjustment layer you are using).
Hope that helps! Naturally when time allows, we'll be making our own tutorials going through from start to finish too :)
--- End quote ---
Just to clarify - does that mean, that information about cryptomatte usage on official Affinity channel is incorrect? https://affinity.serif.com/en-gb/tutorials/photo/desktop/video/365275093/
TomG:
Pretty much, yep. You can use it like that, but it won't work with motion blur and DOF (as can be seen by how pixelated that is in my earlier example of the colored single layer), and really whatever they are doing there with the cryptomatte can be done with other ID matte passes like object, material, etc. The main benefit of cryptomatte is handling DOF and moblur because it is a proper greyscale and not just "on" or "off" (since both effects blend the object in question into what is seen in the background), not having to worry about fringing/aliasing as those should be accounted for afaik, plus having layers that are named and correspond to objects or groups of objects so you can find the mask that applies (which should allow you for example, in their case, to have all the windows on the building on the left grouped and appearing in one mask layer, not as 30 different colors).
So, does their use work? Sure, because nothing is moving or blurred or out of focus - but you can just do that, more correctly, with other types of such "puzzle matte" single layer solutions anyway. None of this is what cryptomatte is intended for, nor is it using the "real and full" cryptomatte data.
davetwo:
You can see how Photpshop handles the Cryptomatte masks iwith the aid of the Exr-IO in this V-ray tutorial: https://vrayschool.com/vray-cryptomatte-exr-in-photoshop/
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