Cryptomatte filter is a component of the Cryptomatte system. It is set up automatically by Cryptomatte to match the existing filter and does not need to be exposed to users or manipulated by them. Cryptomatte filter is a "ranking filter" which takes a float "ID" AOV as an input, and outputs ID/coverage pairs, as described in the Cryptomatte standard. It imitates Arnold filter kernels to produce matching coverage values for samples. These IDs are then ranked by coverage, and two of the ranks are written into each RGBA image.
For example, the RGBA image produced is as follows, if the rank parameter == 0.
- R - ID 0
- G - Coverage 0
- B - ID 1
- A - Coverage 1
The filter is set up by Cryptomatte to match the original filter on which its based.
Sets the starting rank which is to be encoded. For example, if rank == 2:
- R - ID 2
- G - Coverage 2
- B - ID 3
- A - Coverage 3
Cryptomatte uses multiple Cryptomatte filters to write IDs and coverages for an arbitrary number of ranks into RGBA buffers.This is a code to specify which filter kernel is to be used. It is used internally in Cryptomatte to specify which filter kernel is to be used. The filter kernels which are available are gaussian, blackman_harris, triangle, box, disk, and cone.