Warning about using RGB and Luma Curves in Premiere Pro CC

Update: The 7.1 version due out in October is going to fix the issue altogether. Great job, Adobe!

Update: The 7.0.1 patch for Premiere Pro CC fixes some of the below mentioned issues, although unfortunately not all of them.

To my great chagrin Premiere Pro CC changed the way curves operate. Right now the curves, both RGB, and Luma, clip the superwhites and superblacks, and there is no interpolation going on after the curves hit 0 or the white level (255 or 1.0). In CS6, the curves followed the general slope, and it was possible to recover some of the “overshot” material. Right now, if you stick to curves, all clipped data is lost.

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Curve's interpolation in Premiere Pro CS6 allowed to recover superwhites or superblacks, and correct the contrast in the same instance.

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Premiere Pro CC clamps all superwhites and superblacks, and recovering the detail is not possible with the use of RGB or Luma Curves.

This is completely new, unexpected, and if you ever used curves, it changes your workflow dramatically, even if you don’t know it yet.

It means that you must remove the superwhites and superblacks from the clip before you use RGB curves. It means that if you were like me, using curves to apply the basic correction and contrast in one go, you cannot do it now. You have to first make the signal “legal” – reduce the superwhites and raise the superblacks with for example Fast Color Corrector, so that they fit between the range that curves operate on – RGB scale that is not overshot in either direction, even if you are working in the floating point (max bit depth).

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In Premiere Pro CC you need to use Fast Color Corrector or Three-Way Color Corrector to bring the superwhites back into the RGB scale. Only then you can apply curves, and be sure that you are not loosing data.

It also means that there is no real backwards compatibility within the projects that used curves. Your colors will not be the same, if you had any superwhites in the project. I highly advise you to finish your current projects in CS6, and only then create the new ones in CC, being mindful about the necessity to use Fast Color Corrector before applying curves.

Adobe is aware of this issue, and hopefully some fix will come soon, but while using CC 7.0.0 version of Premiere you need to remember about this very real problem.

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8 Responses to Warning about using RGB and Luma Curves in Premiere Pro CC

  1. pribilinskiy says:

    Thanks for describing this new behavior. Maybe your post will influence development and brings back curves filter operation in some future update

    • pribilinskiy says:

      perhaps ProcAmp can be used instead FastCC to bring down the overexposed whites

      • BartW says:

        Good idea. I’m just not used to using ProcAmp at all… especially with the name like this ;)

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  4. Al Mooney says:

    Bart, as you know, this is a BUG that slipped through the cracks in CC and will be fixed very, very shortly. I’m surprised you failed to mention that.

    • BartW says:

      Al, I love you man, but please read carefully the very last sentence: “Adobe is aware of this issue, and hopefully some fix will come soon, but while using CC 7.0.0 version of Premiere you need to remember about this very real problem.”

      I hoped you guys would appreciate the subtlety.

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