Premiere Pro CC: Fast Color Corrector: recommended black/white luminance input levels???

[Ivan Myles]

It depends on the footage. The recommended technique is to use the scopes to keep the Y and RGB values within 0-100 IRE, and the chrominance values within -20 to 120. (Check the delivery specifications, if available.) Adjust the Input or Output black and white levels as appropriate for each clip. If there is part of an image that is known black, for example, adjust the black point until the lowest point on the scope is either 7.5 (for broadcast delivery) or zero (web). Similarly, adjust the white level to ensure the highest point is within range. The following video provides more information:

Premiere Pro CS6 Techniques: 52 Color SIX: Output Levels

[Nick Natteau]

Thank you very much for clarifying, Ivan. It seemed that with most of my footage which was a talking head shot with single keylight surrounded by darkness, the sweet spot seemed to be 170 for white level and 16 for black. But of course the scene never changed. I’ll definitely take a look a this link, thanks again!

[Ivan Myles]

Glad to help. By the way, my comment referenced IRE units, where 7.5 IRE = 16 on the 0-255 scale, and 100 IRE = 255. If you use a bright point of 170 (out of 255), it should correlate to about 67 IRE on the YC scope.

[Nick Natteau]

Thanks again Ivan. BTW, on the premiere pro waveform display, is 7.5% IRE the dotted line just below the 10% IRE line?
I’m assuming that’s why the line is dotted, correct?

And if that’s the case, then would 80% IRE on the 0-255 scale equal 204? As in…80% IRE = 255 x 80% = 204.

Or 60% IRE = 255 x 60% = 153

Does that sound right?

[Ivan Myles]

Yes, the dotted line is at 7.5 IRE.

The IRE values correlate as stated (80 IRE = 204 and 60 IRE 163), but those are displayed values based on a white point of 100 IRE = 255. The Fast Color Corrector settings will depend on the source file; two clips might require completely different settings in order to get the black and white points to look the same onscreen. Adjust the input and output sliders until the image and scopes look good. Refer to the scopes to maintain consistency from clip-to-clip.

Please also note that white point assumes full brightness and full saturation. Clips without any pure white will have the brightest area below 100 IRE. In addition, full brightness can be defined at lower levels, if desired. For example, I tend to target 92-95 IRE to avoid clipping the RGB curves when balancing color.

[Nick Natteau]

Thanks Ivan. Just one final question regarding skin tones and IRE. Is there a rule of thumb for where Caucasian skin tones should fall on the 0-100 IRE scale?

I called Canon yesterday, and they recommended that when shooting in C-Log, Caucasian skin tones should be in the 40% to 60% IRE range on the waveform monitor, (but closer to 60% than 40%). Thanks again.

[Ivan Myles]

Typically use the Vectorscope for evaluating skin tone color: The Vectorscope in Premiere Pro. I’m not sure about luminance, but I suspect you don’t want the people to be glowing. 🙂