9 Replies Latest reply on Mar 13, 2008 4:34 PM by (Nachovilla)

    Cineon LOG 2 LIN render then back again

      Ok so I've done some reading on the subject of converting from Log Cineon to LIN using the Cineon converter utility effect. The problem is I need to render out the Lin files so I can do some touch ups in Photoshop. However I cannot render it out without clipping the whites to 1. Is it even possible to render out a Lin file that can then be converted back to Log without loosing any overwhite data. Im not sure what Im doing wrong, if anything. I am using After Effects 7.0 pro and photoshop cs2 on a windows based OS. Thanks for any help.
        • 1. Re: Cineon LOG 2 LIN render then back again
          Mylenium Most Valuable Participant
          Well, you obviously need to compress the ranges so they fit into a linear format e.g. using the Levels effect. This requires you to work in 16bpc or 32bpc and then use formats that are able to store the info at those full bit-depths. I recommend you read the manual for Red Giant Software's eLin and consult Stu Maschwitz rebelsguide.com site. Certainly someone there can provide you with the correct procedures, perhaps even Stu himself.

          Mylenium
          • 2. Re: Cineon LOG 2 LIN render then back again
            Level 1
            ill give it a look, been to that site before, must have missed that info, thanks.
            • 3. Re: Cineon LOG 2 LIN render then back again
              Why don't you just touch up the cineons themselves in Photoshop and avoid all the trouble?
              Pete O'Connell
              • 4. Re: Cineon LOG 2 LIN render then back again
                Level 1
                Someone can correct me if Im wrong, but I read you are never to composite or work on Cineons (or DPX for that matter) while in Log space, that they should be converted to linear space first, comp, then back to Log. Considering Im manipulating pixels in Photoshop, I thought same rules would apply. I read that the mathmatics behind the blending, paint and compositing tools were made to work while in Lin space, and that unfortunate side effects can happen to the pixels by performing these operations in Log space
                • 5. Re: Cineon LOG 2 LIN render then back again
                  Mylenium Most Valuable Participant
                  Exactly. And you won't even be able to do such a simple thing as determining the correct color of a pixel for painting...

                  Mylenium
                  • 6. Re: Cineon LOG 2 LIN render then back again
                    Level 1
                    Ok so read over the eLin material and spent a bunch of time reading through Prolost blogs, but im still confused. The best I have heard is to render out log and upon import into Photoshop, use adj layers with Lin curve LUTs to compensate. Isn't this just skirting the issue, wont I still be working on Log pixels anyway, just with a LUT to help, which ill have to discard anyway? Another person said I should render to 32 bit, which works but Photoshop cs2 doesn't allow me to do anything while using 32 bit images, I can just view them. So I feel like im back to square one. mylenium I remeber you saying I should compress using levels, but how do I know if im right? Am I suppose to eyeball it? Sorry, im just really frustrated...
                    • 7. Re: Cineon LOG 2 LIN render then back again
                      Level 1
                      Nachovilla said: "I need to render out the Lin files so I can do some touch ups in Photoshop"

                      If you are just touching up cineons using the stamp tool then you are effectively just pushing around cineon colour space pixels so that's absolutely no problem in photoshop.

                      Mylenium, elaborate "Exactly. And you won't even be able to do such a simple thing as determining the correct color of a pixel for painting... "

                      Why touch stuff up in photoshop anyway when you can paint in AE?

                      So there
                      Pete
                      • 8. Re: Cineon LOG 2 LIN render then back again
                        Jonas Hummelstrand Level 2
                        Let me suggest you get mark Christiansen's excellent "After Effects CS3 Studio Techniques" for great tips and workflows for cineon files (and other compositing tricks.) A must-have book!

                        - Jonas Hummelstrand
                        http://generalspecialist.com/
                        • 9. Re: Cineon LOG 2 LIN render then back again
                          Level 1
                          Using Photoshop because of the healing brush tools and the patch and extraction tools. I am a big proponent of the After effects studio tech books, even have the last two editions. But none of them ever talk about what to do if you Convert from Log to Lin render out the sequence and then reimport it and convert back to Log without losing any of the overbright values. I know it sounds strange that I am using PS for this but it is just easier than creating multiple layers that then have to be blended in proper. In any event it is more out of principle now that I want to know if anyone has a procedure for this. I can't be the first one who has tried to convert Log to lin and rendered out a 16bpc image and then wanted to convert it back. Ill mull over my books again, hope I havent turned everyone off this subject