[Tig] ProRes444 necessary when grading BW

Joe Owens jpo at prestodigital.ca
Fri Mar 15 22:51:36 GMT 2013

It really depends on what's in the container.  ProRes 4:4:4:4 can be either Y'CbCrA or RGBA.  If it was Y'CbCr, and transferred as luminance-only, you are actually grading 4:0:0:0.

If the ProRes container is an RGB  color scan of something originally B&W, then it's likely R=G=B, which is just a waste of bandwidth; but if your ProRes is a color picture that you are making B&W, then a nice RGB 4:4:4 could have some benefits.

Recall, of course, that Y', the luminance component of a color signal, is not actually 100% Green, but a matrix of RGB in a roughly 70/20/10 mix.  Alexis Van Hurkman covers some approaches to black & white utilizing the Resolve color mixer quite nicely in a few of his tutorials.

If you are grading a color scan to create the black & white, it depends on whether you want to redefine the Y' matrix.  There used to be a cheat on most telecines that copied the green channel into all three to create a monochrome signal, but it never looked as nice as grading for a neutral  and then desaturating.  Black and White stock has a different spectral sensitivity (and this differs between acetate and nitrate, and so on), so when anyone simply refers to "just black and white",  they're missing the nuance.

On 2013-03-15, at 3:59 PM, David HJ. Lindberg wrote:

> I started to wonder this week if it's necessary to use ProRes444 files when
> grading something bw?

Joe Owens
Presto!Digital Colourgrade
302-9664 106 Avenue
Edmonton, Alberta T5H0N4
+1 780 421-9980
jpo at prestodigital.ca

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