4 Replies Latest reply on Jul 29, 2010 7:59 PM by Colin Brougham

    Helpful tip when keying with Ultra

    Colin Brougham Level 6

      This may be common knowledge, so please forgive me if I'm doubling up this information...

       

      Ultra is pretty amazing keyer, particularly when coupled with an MPE-capable graphics card--being able to key in realtime is an incredible limit-lifter. However, like most keyers, Ultra has a tough time when it comes to knocking out the background around areas with fine detail, such as hair. This is especially an issue with more highly-compressed footage, such as DV, but I'm even finding it with DVCPROHD 1080p.

       

      When I previously used Keylight in AE for keying work, I would frequently use two instances of the effect on a tough clip: one was a hatchet, knocking out the majority of the chromakey wall, and the other was a scalpel, finely working around the edges. I actually found this tip in the Keylight manual (pays to read those, sometimes!). Well, it occured to me that I might be able to do the same with Ultra--and so it is!

       

      Thanks to hardware MPE, I can stack to instances of Ultra on a clip, and really fine-tune the key, and I still get realtime playback to check how clean the result is.

       

      Hope someone finds this useful!

        • 1. Re: Helpful tip when keying with Ultra
          Todd_Kopriva Level 8

          Yep. That's a good general practice for keying. And it's hard to get beginners to do. I just recorded a beginner-level video training series for After Effects (finished yesterday!) and I made a point of showing how even an easy key requires two instances of the keying effect (in this case a special pass for the hair).

          • 2. Re: Helpful tip when keying with Ultra
            Colin Brougham Level 6

            Well, we're so groomed to think that everything should be One Click Magic(TM)-which Ultra almost is--that that sort of mentality is to be expected!

             

            I have noticed that, even with the dual effect (or maybe because of it), I get quite a bit of "shimmer" around the hair. Is this because of the "vector" nature of Ultra? Any way to counteract this without setting Choke so high that it carves into the foreground subject?

            • 3. Re: Helpful tip when keying with Ultra
              Todd_Kopriva Level 8

              I don't have any experience with refining keys around hair with Ultra in Premiere Pro yet. I do all of my compositing work in After Effects. I'll try some things out and get back to you.

              • 4. Re: Helpful tip when keying with Ultra
                Colin Brougham Level 6

                Thanks Todd. I just moved one of the clips into AE and used Keylight as a test; with just a scant amount of tweaking, I got a much better result than I could with Ultra. For shots featuring this particular individual, I think that that's what I'll have to do--poofy, wispy hair that's a nightmare to pull. Fortunately, after I set up the key once, it's a copy and paste job. I'll play more with Ultra to see if I can get a better result, but it's good to know that Keylight is there as my safety net--I'm glad that didn't get pulled when Ultra came along! I'd be happy to send a frame of this shot I'm working on, so you can see if you'll have better luck, if you like.

                 

                Now to diagnose why I'm getting weird purple edges when I use DL to send the alpha comp to Premiere... but that's another story.