• Adobe Premiere Pro

  Legal Chroma Colors

  Posted by Jason Freets on December 16, 2013 at 5:37 am

  I can’t tell you how frustrated I am with determining if the UV colors captured from a VHS source are in the legal limits?

  In terms of luma (Y component), it’s easy to use the scopes (waveform monitor for example) to determine if you are in Studio RGB (16-235) or HD (0 to 255). You can easily view the scopes to see when your luma values are out of whack or illegal.

  I can’t say the same is true for Chroma. Chroma (UV), on the other hand, I’m not sure how to detect if my Chroma’s are clipping or under-saturated? I keep reading everywhere that you want safe broadcast colors and to check the Chroma levels. I always keep asking myself but how? Which scopes? What am I looking for in the scopes or watching to ensure that a digitally captured video is within the legal colors? There’s the realization that not all YUV colors map to the RGB space legally. Visualizing this or being able to detect for such is what I am looking for.

  For example, I’ve captured a bunch of VHS tapes to digital. I’d like to verify that my digitally captured file has legal UV ranges. Why? Because later on, I don’t want to have to come back and re-capture from the VHS source (especially if I no longer am in possession of it).

  So not sure what to do? What scopes or tools are there available to do this?

  Final Cut Pro seems to have the following:

  Displaying Excess Luma and Chroma Levels in the Viewer and Canvas

  Zebra Stripes

  A big however is that I never used this, so I’m not sure if that’s what I am looking for in a way to verify the proper Chroma levels.

  Suffice to say, I am looking for a way to detect that the Chroma levels captured are OK with future and current digitally captured videos.

  How do I approach this? Which tools? What am I looking for if I were to use a certain tool?

  Any guidance is greatly appreciated!

  Kevin Monahan replied 12 years, 5 months ago 2 Members · 1 Reply
• 1 Reply

• 

  Kevin Monahan

  December 16, 2013 at 8:54 pm

  Hi Jason,
  There are no “zebra stripes” in Premiere Pro (make a request for them here: https://www.adobe.com/go/wish).

  You have to use the vectorscope to detect excess chroma (and the Waveform monitor for excess luma). Before FCP had those visual indicators, I used the waveform monitor and vectorscope in that application.

  To be sure your color correction is within safe limits, you can always use the Broadcast Colors effect to be sure that you’re within broadcast safe spec.

  A tutorial on using the vectorscope: https://library.creativecow.net/devis_andrew/Premiere-Pro-Vectorscope/1

  Thanks,
  Kevin

  Kevin Monahan
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  Adobe Systems, Inc.
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