Colour correction

[paul_round]

Does anybody have a formula for translating camera stops into the colour corrector?

[tscholton]

Poking around I found this thread on another site. Also in Sapphire v4 under S_FilmEffect there are controls for Neg Exposure, Print Exposure, Print Lights and lots more.

Jeff

[Saran Sirikasamsap]

increasing the exposure by one F-stop results in an image with the luminance value double that
of the original….does this help ?

[prajjwal]

@rohit 23467 wrote:

increasing the exposure by one F-stop results in an image with the luminance value double that
of the original….does this help ?

Actually, increasing by one F-Stop doubles the luminance of the original IN LINEAR color space. If you are working in FFI, there is a 99% chance that you are working either in video space (aka sRGB or gamma 2.2) or in log space.

For video space (HD, DigiBeta, some JPG you found online, etc…) do a gamma of 0.45, then gain 200%, then gamma 2.2. I suggest using 3 separate CC nodes in Batch, as I am not sure of the order of corrections within a single CC node. (You should be in 12 bits, otherwise the banding is gonna sting!).

Actually, even in 12 bits, this is pretty brutal, so I suggest taking a peek and emulating the result with a curve.

For log space, take your original Cineon file, add a LUT Editor with the default values (Log to Lin, ref white 685, ref black 95, highlight 4095, shadow 0, Gam Film 1.0, Film Gamma 0.6, Softclip 0). Add a CC node after with a gain of 200% then apply a LUT Editor with default values but this time Lin to Log.

Again, I strongly advise to take a peek, then emulate the look with a curve in CC.

**SIGH** Now if FFI could give us 32 float or even 16 integer bit depths… we could finally join the world and work in linear like everybody else… Then working in f-stops would only require a single gain adjustment…

— Xavier

[Saran Sirikasamsap]

thats a good explanantion…thanks

[pixelmonk]

Managed to build myself a macro in batch, using a frame rendered one stop lighter in Shake, as a reference.
Works a treat.

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