1 Reply Latest reply on Jan 21, 2013 2:06 PM by Fuzzy Barsik

    Need help with a cinema project - asked to supply in HDTV rec 709

    Mitchell Remes

      Firstly I apologise about this lengthy post, I am not a professional colour grader and I will no doubt get shot down for some of the idiot questions I am about to ask, but you guys have more than helpful in the past.  I have been editing for a number of years based in the UK and am no expert.

       

      I have been commissioned to create a 30 second cinema advert which is to be supplied in HDTV 709 which will be transferred to a DCP in an XYZ colour space, the transfer is out of my hands and I will supply a TIFF sequence (the audio is another workflow and I am not concerned about it in this post).  I am not using a video card and am working on CS5.5, plus I am beginning to realise that I need to calibrate my monitor using a hardware calibration device (any recommendations).  We are shooting on a Panasonic AF-101 and I understand that the colour space will not be 4:2:2 but 4:2:0, 8 bits, AVCHD codec.  I have seen another cinema advert where this camera was used and in my humble opinion it stood up quite well.  Can anyone advise otherwise?

       

      My main question is with regard to the rec 709 colour space and how it is handled in Premiere (I sense a big sigh as this is an old chestnut that everyone seems to be trying to crack).  It might sound a bit naive but my main concern is about getting the black, white and gamma levels correct.  I know there are a raft of other issues involved here but I would like to get to the bottom of this issue before I continue my research.  As I understand it rec 709 requires that the levels remain between 16 and 235, however there is headroom from 236 to 254 and footroom 1-15 and 0 and 255 are used for sync.  So here is the million dollar question, when I import my footage what colour space is premiere working in and how do I manage my workflow between Premiere and After Effects and where should I colour grade?

       

      I believe that premiere works in full swing 0-255 Adobe sRGB using floating 32 bit, I could be wrong though, so what is happening to my footage on import?  Does the Panasonic use the full range in it's AVCHD codec and therefore I am seeing the full range in Premiere, even though a colour space conversion has taken place?  The big question then is, do I have to restrict the output levels to 16-235 on export as a TIFF sequence or not?  Should I restrict to 1-254 so that I do not impinge on the sync signal, or alternatively do nothing?  This is all assuming that I do everything in Premiere.

       

      With regards to After Effects I have done some basic research but it appears that I can choose to work in HDTV rec 709 either full scale or specifically choose a limited 16-235 HDTV colour space, also I believe that if I buy the calibration hardware I can give After Effects my monitor's profile as well.  If I import the project into AFX without restricting levels in Premiere do I need to interpret the footage in a particular way if I choose a HDTV rec 709 as a project setting (should I choose HDTV 16-235 instead)?  I must admit to being a bit confused, this appears to be a hangover from analogue systems, is the 16-235 limit definitely part of the rec 709 spec?

       

      There are a  raft of issues here but if nothing else I want to ensure that my footage doesn't look bleached out or crushed upon transfer as all my efforts will be in vain?    

        • 1. Re: Need help with a cinema project - asked to supply in HDTV rec 709
          Fuzzy Barsik Level 4
          We are shooting on a Panasonic AF-101 and I understand that the colour space will not be 4:2:2 but 4:2:0, 8 bits, AVCHD codec.

          You can plug Atomos Samurai to your AF-101 so as to shoot with 4:2:2.

          As I understand it rec 709 requires that the levels remain between 16 and 235

          No, HDTV Rec.709 and sRGB IEC61966-2.1 have the same primary colours. 16-235 luma adjustment, which is sometimes required for TV broadcasting, is deployed in HDTV Rec.709 (16-235), SDTV NTSC 16-235 and SDTV PAL 16-235.

          When I import my footage what colour space is premiere working in?

          sRGB IEC61966-2.1 (not Adobe sRGB).

          Does the Panasonic use the full range in it's AVCHD codec and therefore I am seeing the full range in Premiere?

          Yes.

          How do I manage my workflow between Premiere and After Effects?

          Set your AE project to 32-bit and choose either sRGB IEC61966-2.1 or HDTV Rec.709 colour space. Do NOT linearise your working space unless you fully understand linear workflow.

           

          If you work in 16-235 colour space or get some footages in 16-235 colour space, see e.g. this thread on how to reverse adjust luma range for PrPro.

           

          If you import footages exported with HDTV Rec.709 (16-235) colour profile into AE, you should interpret them accordingly irrespective of what your current working space is.

          Do I have to restrict the output levels to 16-235 on export as a TIFF sequence or not?

          Don't think it's necessary for a cinema project. Ask your recipient for a particular requirements.

          Where should I colour grade?

          That depends. Some complex colour correction may require compositing work, which is better done in AE.

           

          So as to understand colours better check for Color Correction Handbook by Alexis Van Hurkman.