Legalising video using CC FX.

farss wrote on 6/4/2007, 10:48 PM

Just posted how I do it here . As I say in the notes only for video, not for graphics or stills that might be Computer RGB. In the past I didn't have the bend at the top the curve which resulted in a slight shift in all the levels. I've revised my approach based on how the Sheriff seems to do it although it's a much smarter box. Even so if you look at it's specs you'll notice there's a number of options to how to solve the problem.

Bob.

Comments

Grazie wrote on 6/4/2007, 11:05 PM

Thanks for going to the trouble Bob. Much appreciated. - g

briggs wrote on 6/5/2007, 9:50 AM

Thanks, Bob. This is very helpful.

GlennChan wrote on 6/5/2007, 3:29 PM

To legalise your video you have to make sure that the luma values AND the composite values are in legal range.

The broadcast colors filter will do this, though it doesn't necessarily look the best.

With the color curves, I don't believe that ti will necessarily bring all the composite values into legal range (and the maximum composite values allowed vary from broadcaster to broadcaster... generally no more than 115 IRE).

Marco. wrote on 6/5/2007, 3:44 PM

So why don't you simply use the Broadcast Colors filter with adjusted Smoothness levels? I must be missing something.

Marco

farss wrote on 6/5/2007, 4:40 PM

Nope, not missing anything!
With the adjusted smoothness levels it works the same as my CC curve, good find. Without adjusting the smoothness it wasn't doing what I wanted so that's why I went elsewhere.

Glenn is right, the CC will not address the composite levels issue.

The BC FX can also control the composite levels although with some potential for out of gamut colors to get clipped, just try applying it to the Linear Red To Yellow gen media. However I'm not seeing anything from a camera that's out of gamut so that shouldn't be an issue.

Bob.

busterkeaton wrote on 6/6/2007, 12:21 AM

Why Color Curves and not Levels in this instance?

GlennChan wrote on 6/6/2007, 2:11 PM

Levels can't do the roll-off / curve in the highlights. It also can't clip colors at 16 and 235.