Re: Digest for ocio...@googlegroups.com - 2 updates in 1 topic
Joseph Goldstone <jgold...@...>
Pretty sure there was a killer typo in Guarav’s illustration of tetrahedral interpolation though. There was supposed to be a second edition of that book (“Digital Color Imaging Handbook”, not “Digital Color Handbook”), and Amazon still shows a mock-up page for it, but it never came out.
To ARRI Partner Program members who are curious about this we recommend one of Kang’s books. You could look at pp. 70-72 of “Color Technology for Electronic Imaging Devices":
https://books.google.com/books?id=vzQH3qA_RKkC&pg=PA72&lpg=PA72&dq=kang+tetrahedral+interpolation&source=bl&ots=DC1eh_t_Xh&sig=3DrpvVzNk2RaTz3fZV7c32Wm2Hw&hl=en&sa=X&ved=0ahUKEwjql8_iz6vcAhUNKXwKHfneA8cQ6AEIVzAG#v=onepage&q=kang tetrahedral interpolation&f=false
But there’s also the Truelight documentation, and Richard Kirk does a nicer, I think, job of presentation than Kang (perhaps because Richard only outlines one scheme, whereas Henry Kang seems to outline every conceivable interpolation scheme ever invented). If you go to this page:
and download the "Truelight Software Library” document from 2006, § 6.6 (“Colour Cube Transforms”), pp. 55-57, does a nice job and includes straightforward C code. I haven’t personally tested the code by cutting and pasting but I suspect it works. You want to be sure that the tetrahedra are cut in such a way that the (0,0,0) to (1,1,1) chord of the cube runs along tetrahedral edges — this is kind of the natural way to do it, and in fact is how the (probably little used) 3D LUT processors in the original DLP Projector electronics packages did it, back in the day — a handy thing back when image processing components were twenty years behind today’s components in terms of performance.
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