Premiere Pro and broadcast levels

[Angelo Lorenzo]

*Sighhhhhhhh

Alright, lets get this started.

From https://camerahandbuch.wordpress.com/2012/08/03/premiere-rgb709-problem/ (edited for clarity)

“YUV and RGB do not traditionally have the same black and white levels. In 8-bit YUV, black is represented as 16 but in 8-bit RGB black is 0, and 8-bit YUV white is 235 but 8-bit RGB white is 255. Any values under 16 in YUV are considered Super Black and any values over 235 are considered Super White.

Many applications (like Final Cut Pro, Premiere Pro, After Effects) will convert YUV to RGB in such a way that expands and maps the black/white levels of YUV to the black/white levels of RGB, and likewise they will convert RGB to YUV in such a way that contracts and maps the black/white levels of RGB to the black/white levels of YUV. This is considered converting YUV to Full Range RGB (or Computer Range RGB) because the 16-235 values of YUV are expanded and mapped to the Full Range 0-255 of RGB.

While technically Super White and Super Black are illegal YUV values, some users do like to preserve them in their workflows and so there are some applications like Sony Vegas and Avid Media Composer that are aware of the color levels differences of YUV and RGB data. These applications allow workflows where YUV can be converted to/from RGB that provides more of a one-to-one mapping of the color levels where 16-235 YUV is converted to 16-235 RGB. This is considered converting YUV to SMPTE Range RGB (or Video Range RGB) because the 16-235 values of YUV are mapped to 16-235 RGB.”

This would map 0 IRE or, in the case of PAL, 0.3v to an RGB value of 0, and 100 IRE/1.0v to a value of 255. https://forums.adobe.com/thread/1107336

Use your program scopes and, if you have access to external scopes, please check program material. Do not use RGB values in Premiere to make any critical evaluations when it comes to broadcast levels as RGB levels will be compressed when output to a YUV video format.

If you want to preserve super whites and super blacks, you need to take care to use effects that process YUV directly (they will have a YUV icon) and export to a YUV supporting video format. If some care isn’t taking then you’ll just clamp to YUV legal values.

[Craig Ricker] “That moves us onto chrominance.
To ensure I am meeting the broadcast legal standard for chrominance I can use the vectorscope. I understand what the vector scope is showing, but I do not know if my levels are supposed to fall under 75% or 100%? When I put up DV Pal bars the vectorscope shows maximum chrominance of 75% where as when I put up HD 720p Bars they show maximum chrominance of 100%. Is that a hint as to what is legal?”

https://blog.ieba.com/wp-content/uploads/2010/06/ReadWaveformVector.pdf
https://forums.creativecow.net/thread/3/866589
75% is your setting for both PAL and NTSC; the first link will teach you how to read a vectorscope.

[Craig Ricker] “RGB Parade…
Is this showing the luminance values of each individual color channel? I assume this is more for color correction than actually bringing levels into safe limits, as every channel appears to be clipped on all colors. And thus what is safe limits?”

RGB and YCbCr parades are for color correcting only, you’ll notice their scales are an arbitrary 0-100. I would suggest trusting the YC waveform with the chroma overlay in addition to the vectorscope.

As for some of the specifics of legality, I’m not familiar enough with PAL to say how far the chroma can fall outside of max luma (NTSC allows for an additional 20%) or how PAL color bars should be laid to tape.

[Craig Ricker] “Here is another test I could not get to work. I create a 0,0,0 black, a 255,255,255 white and a 16,16,16 in photoshop. No matter what color profile I gave the document when I displayed this graphic on my 720p timeline it displayed 255,255,255 as 1.0v 0,0,0 as 0.3v and 16,16,16 as like 0.35v

So I could not get any graphics to fall into what I suspect is “illegal white” of 1.1v?????”

See the first set of paragraphs. Unless you use some wayward workarounds, because Premiere uses full range RGB, it’s not really possible to get superwhites from graphics. If you’re using AE to create overlays then you may want to be critical of your RGB levels if, say, you’re bringing it to Avid in an RGB based video file or image sequence.

——————–
Angelo Lorenzo

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