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chrisw44157881
chrisw44157881
Inspiring
September 15, 2017
Question

proof that premiere clips at srgb colorspace

  • September 15, 2017
  • 1 reply
  • 3655 views

if you've ever wondered if premiere really did clip its color engine at srgb, look no furthur. I have undenialable proof!

You cannot grade in linear color if the lut gamut is larger than srgb or you'll get primary color clipping.

For example, if you use an Arri Logc to Linear, then sandwhich a 32bit gaussian blur and then a Linear to Logc, with a viewing lut, it

will clip shown here. For note, After Effects has zero issues with the exact same layout. Premiere has max bit depth, max render quality and composite in linear color all checked. This is not so much a bug as it is a deal breaker for any grading in Premiere higher than srgb. As such, any lut that tried to expand to a larger gamut will get clipped as well.

I will expand my tests to include jpeg2000 which adobe says supposedly imports as rec. 2020. we shall see adobe, we shall see...stay tuned..

nope.

If you were hoping exporting a PQ rec.2020 would import differently, bad news as well. true hdr only exists if you disable luts.

    This topic has been closed for replies.

    1 reply

    R Neil Haugen
    R Neil Haugen
    Legend
    September 15, 2017

    Love your diligence at sleuthing through a proof!

    Yup, PrPro is and only is "standard" BT(Rec.)709 ... period. Which is sRGB ... as a basic definition. It is not setup like AfterEffects, which does  allow setting color space to a certain extent.

    This of course makes using it with some of the wider-space monitors a bit interesting, perhaps at  times a challenge even. Ahem. But there it is.

    With Rec. 2020 coming, and HDR ... there is need of some alterations here. So as always, I suggest people file the bug/feature report on this ...

    https://www.adobe.com/cfusion/mmform/index.cfm?name=wishform

    Neil

    Everyone's mileage always varies ...
    E
    excited_Genie16B8
    Legend
    September 15, 2017

    PrPro is and only is "standard" BT(Rec.)709 ... period.

    One wonders, then, what is the purpose of being able to change the Colorspace to Rec. 2020 in the Lumetri Scopes?  The easy and assumed answer is to get PP working in that Colorspace, no?

    R Neil Haugen
    R Neil Haugen
    Legend
    September 15, 2017

    Yea ... that's assumed, and ... I've puzzled over that one. From the Wiki for BT(Rec) 2020 ...

    ITU-R Recommendation BT.2020, more commonly known by the abbreviations Rec. 2020 or BT.2020, defines various aspects of ultra-high-definition television (UHDTV) with standard dynamic range (SDR) and wide color gamut (WCG), including picture resolutions, frame rates with progressive scan, bit depths, color primaries, RGB and luma-chroma color representations, chroma subsamplings, and an opto-electronic transfer function.[1] The first version of Rec. 2020 was posted on the International Telecommunication Union (ITU) website on August 23, 2012, and two further editions have been published since then.[1][2][3][4][5]

    There's a lot of stuff in there that PrPro doesn't seem 'settable' for ... so putting the scopes into 2020, when you can't set anything else ... I've known a couple that tried this, with puzzling results. Not precisely what they'd expected, and they weren't sure ... exactly ... what they were seeing.

    Wish I knew more about this.

    Neil

    Everyone's mileage always varies ...
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