Cary Knoop
Veteran
Unless your source is 4:4:4 RGB clamping is still no guarantee your colors will not be out of gamut. Most video is in Y'CbCr format. If there is chroma subsampling then going back to RGB may create out of gamut situations.
illegal (or otherwise toublesome) saturation levels?
- Thread starter rayortiz313
- Start date
There is no "out of gamut" with BT.709-type digital sampling. The digital encoding is incapable of representing colors outside of the BT.709/sRGB gamut. Maybe you are thinking of xvYCC or something else, but it doesn't exist for standard HD video. The entire BT.709/sRGB gamut is available and legal.
You only need to ensure that RGB levels are in the 0%-100% range. That's it. That's the entire definition of a "legal" digital signal. When you do that, YCbCr levels will be in range also. Chroma sub-sampling can only cause transient overshoot/undershoot, and those are actually allowed.
You only need to ensure that RGB levels are in the 0%-100% range. That's it. That's the entire definition of a "legal" digital signal. When you do that, YCbCr levels will be in range also. Chroma sub-sampling can only cause transient overshoot/undershoot, and those are actually allowed.
morgan_moore
Major Contributor
Bal
One thing of interest is that when import my nex5n to resolve it appears clipped but I can pull it back - showing that values above 100% are somehow there upon import - which leads one to imagine that one could export values above 100% too not that I think they would damage a device - but could they cause odd looks maybe ?
One thing of interest is that when import my nex5n to resolve it appears clipped but I can pull it back - showing that values above 100% are somehow there upon import - which leads one to imagine that one could export values above 100% too not that I think they would damage a device - but could they cause odd looks maybe ?
Yes, you can export values above 100%, but it won't cause odd looks. The parts above 100% just get clamped to 100% by the display, or maybe somewhere earlier in the pipeline depending on what kind of video display software and hardware you're using. Doing the clamping yourself won't change what you see on the display.
That's not to say that highlight clipping looks good. Highlight handling is a whole 'nother topic.
That's not to say that highlight clipping looks good. Highlight handling is a whole 'nother topic.
Cary Knoop
Veteran
It won't cause off looks? What you will get is hard clipped highlights.
If you properly color correct footage you should not export above 100%.
In resolve when you export with video levels most codecs do clip values above 100%, H.264 being one of the exceptions but the result will still be clipped when viewed.
I'll check out of this topic, I guess some people think all is well as long as the display does not explode!
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morgan_moore
Major Contributor
I think we all know that hard clipped highlights are (in the main) horrible.
Usually I roll right off even if I have a blown window Ill pull it back - my personal style.
But there is a difference between horrible.. what the OP wanted.. and legal/troublesome which was the title of the thread.
My thesis is that you can make it look as horrible as you want without becoming illegal/troublesome.
S
Usually I roll right off even if I have a blown window Ill pull it back - my personal style.
But there is a difference between horrible.. what the OP wanted.. and legal/troublesome which was the title of the thread.
My thesis is that you can make it look as horrible as you want without becoming illegal/troublesome.
S
Cary Knoop
Veteran
Sure, and if the poster of this topic gets his video rejected due to QA errors related to gamut he just will tell the distributor/broadcaster "members on a forum told him it is OK because he only used RGB values in his editor that were within legal ranges".
morgan_moore
Major Contributor
Back round the circle 
were how does one create thes QA errors?
were how does one create thes QA errors?Google "video program delivery standards" and you will find a sampling of different networks' standards.
E.g., the BBC's, standards, which are based on EBU R 103. See sections 1.2: Signal Parameters and 1.2.1:
Video Level Tolerance of the BBC specific technical delivery standards document. It talks about RGB levels and ranges of code values. If you understand how BT.709 converts R'G'B' levels to Y'CbCr code values, you will see that constraining RGB values to the 0-100% range will ensure that Y'CbCr code values will be in range also, aside from transient overshoot/undershoot caused by chroma sub-sampling reconstruction errors or compression noise. Transient overshoot and undershoot are actually allowed under the standards. The BBC's code value ranges, for example, are -5% to 105%, and excursions outside of that range are allowed so long as they total less than 1% of the image area. Please note that what they call "out-of-gamut" does not refer to the color gamut, but rather to the range of code values.
Some networks, e.g. PBS, clamp RGB levels to the 0-100% range, so you don't have to.
E.g., the BBC's, standards, which are based on EBU R 103. See sections 1.2: Signal Parameters and 1.2.1:
Video Level Tolerance of the BBC specific technical delivery standards document. It talks about RGB levels and ranges of code values. If you understand how BT.709 converts R'G'B' levels to Y'CbCr code values, you will see that constraining RGB values to the 0-100% range will ensure that Y'CbCr code values will be in range also, aside from transient overshoot/undershoot caused by chroma sub-sampling reconstruction errors or compression noise. Transient overshoot and undershoot are actually allowed under the standards. The BBC's code value ranges, for example, are -5% to 105%, and excursions outside of that range are allowed so long as they total less than 1% of the image area. Please note that what they call "out-of-gamut" does not refer to the color gamut, but rather to the range of code values.
Some networks, e.g. PBS, clamp RGB levels to the 0-100% range, so you don't have to.