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PRIMATTE
NUKE
For a description of the Primatte RT+ algorithm, go to Explanation of how Primatte RT+ works
on page 217.
For a description of the Primatte RT algorithm see Explanation of how Primatte RT works on
page 218.
Explanation of how Primatte works
The Primatte chromakey algorithm is a sophisticated method of colour space segmentation
that can be easily explained to help a user achieve maximum effectiveness with the tool. Basically Primatte segments all the colours in the foreground image into one of four separate categories. The result is a 'spill suppressed' foreground image and a matte which is used to apply
the modified foreground to a suitable background.
Primatte works in 3D RGB colour space. Here is a visual representation of the Primatte algorithm after an image has been processed.
By operating the Primatte interface, the user essentially creates three concentric, multi-faceted polyhedrons. These can be pictured as three globes (or polyhedrons or polys), one within
the other, which share a common centre point. The creation of these polyhedrons separates all
possible foreground colours into one of four regions; inside the small polyhedron (1), between
the small and medium polyhedrons (2), between the medium and the large polyhedrons (3) and
outside the large polyhedron (4).
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