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What is difference between SDI output 4:2:2 Full to legal and 4:4:4RBG full to Legal


Soumitra Sarkar

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In recent time I grade a web series keeping my Baselight SDI output setting 4:2:2 full to legal . When I saw the output in another machine keeping setting 4:4:4 RGB full to legal, it's look like shadow up and look my not poper grading. I don't understand why happened. As I know 4:2:2 and 4:4:4 effect only chroma label. 

Usually I kept my settings 4:4:4RGB full to legal. 

Plz help me to understand...

 

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4:4:4 normally is RGB (although it *can* be YUV as well) and RGB usually is expected to be a full range signal.

4:2:2 is YUV and that is usually expected to be a legal range signal.

In any way, both RGB and YUV *can* technically be either full or legal range.

However, it all depends on how the monitor is configured. If that expects legal range and you're sending it a full range signal, 
the blacks/whites will look crushed. If it is set to expect a full range signal and you're sending out legal range, then blacks will look lifted and whites dimmed.

So when your monitor is set to expect RGB, then it might by default assume that this comes in full range.
If your system is set to output legal range.... that will not look good. 
To fix it, either set the monitor to legal range, or set Baselight to output full range (which is what I'd do).

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Hi Soumitra,

the level of black and white in the signal will not change between 422 and 444 Full to legal.

Are you maybe using Sony displays with the input range set to 'Full'? It is a common pitfall to have Sony displays set to full range, but feeding a 422 signal. Because with 422 signals they will always treat them as 'Limited' range. You can verify this by switching the display between full and limited input. For 422 signals, nothing will change in the image. That is why I recommend to use 'Full to Legal' in Baselight and 'Limited' on the display. Then it is correct for both 422 and 444 signals.

Cheers, Andy

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