13 Replies Latest reply on May 8, 2012 9:11 AM by john_orban

    Using Keylight 1.2


      After Effects CS3 - trying to learn how to use this.


      When I did my first key it is absolutely BEAUTIFUL...nice edges...right out of the box.


      Only problem is that part of my foreground character is transparent...therefore, the background shows through.


      I can't for the life of me figure out what controls to twiddle...and I've twiddled a number of them...to try and get rid of that transparency without losing my key. The docs that come with KeyLight are pretty sparse and seem to imply that you already know how to use it.


      I've thought about putting a black background behind her, but don't know how to make the black background just be her and not everything else.


      It seems to me there should be a way to create a basic matte with Keylight that I could use on a separate black layer?


      Still new to AE but trying to learn.


      Any help or points to links that can explain how to do this would be great.




        • 1. Re: Using Keylight 1.2
          Adolfo Rozenfeld Adobe Employee

          Hi, John.

          Before anything, if in Keylight you change the view menu from "Final Result" to "Screen Matte", you'll see a grayscale representation of your matte. In other words, black areas represent full trasparency, white fully opaque areas, and shades of gray, everything else (semi-transparency).


          You will probably see there are some gray spots in your forgeground. These are areas of semi-transparency. You need to get rid of these spots, trying to not kill semi-transparency in other areas, or you'll get a really harsh key.


          I would first raise a bit the Screen Gain Parameter. Don't go higher than, say, 110. As a general rule, if you have to move a slider too much, it's because you would have to do something else instead

          So, after that go to the Screen Matte section of Keylight and you'll see controls like "Clip black" and "Clip white". These are analogous to input black and input white in Levels - they force almost transparent areas to become fully transparent, and near opaque areas to become fully opaque. This should to the trick. Again, don't push it too much or you'll loose semi-transparency in hair areas, etc.


          Let me know if this worked.

          • 2. Re: Using Keylight 1.2
            Frédéric Leclair Level 1

            Could an effect like colorama be applied so that every grey in scale of key could be brought back to full black by limiting weel (after key has been applied) ?

            • 3. Re: Using Keylight 1.2
              john_orban Level 1



              Well, I guess I'm an idiot. I can't seem to get it to work. Increasing the screen gain helps smooth out the few wrinkles that remained in my green backdrop.


              Playing with the Black and White Clipping helps some but the transparency is still there.


              I guess the problem is that she's wearing a green shirt, albeit not the same shade of green as the backdrop. Of course, the ONLY ONE I wanted to green screen shows up with a green shirt on. I guess it's just not possible to do it.


              I've tried putting a black solid behind her and that works great...all the transparency is gone.


              I just don't know how to create a mask on a black solid that perfectly matches her. Trying to draw with the pen tool would be impossibly difficult...maybe that's how it's done, I don't know...seems to me there ought to be SOME WAY to create an "inverse" mask using Keylight since when I look at "Screen Matte" I get a nice clean "cutout" of her image.


              I'm clearly over my head with this. Never did really understand masks from Paint Shop Pro V7.0 on to Photoshop CS3.

              • 4. Re: Using Keylight 1.2
                Adolfo Rozenfeld Adobe Employee


                Don't worry, you're not an idiot.

                This is a craft that takes time to master.


                Using green clothes when doing green screen work is a big, big NO. Make sure you write that down


                Now, the problem is - the best way to mask something so it matches the shape of a keyed object is use the matte from the key as a mask... As you can probably anticipate, the problem is... the holes in the matte will also go through.


                But don't worry. Here's something that should work.


                Pre-compose the keyed layer (you can duplicate before Pre-Composing if you don't want to compromise the original).

                You are only pre-composing it because some effects that will take the key as source wouldn't see the key but the original unkeyed footage as result if it wasn't in a Pre-comp. This pre-comp can be turned off. You don't need to see it. The effects need to see it


                Apply the Set Matte effect in the solid. Make sure it points to the Pre-Comp in the "Take Matte from" menu, and uses Alpha Channel in the "Use for Matte" menu. This will mask the solid with the key. Then apply either the Simple Choker or Matte Choker effect (Effects > Matte) to the solid, and tweak the choke so that it closes the holes. This will give you a solid that is roughly masked like the keyed layer (the matte choking may erode the edges but nobody will see them anyway).

                • 5. Re: Using Keylight 1.2 - I AM an idiot!
                  john_orban Level 1

                  Well, I'm trying to understand what you're talking about, but it's just not making sense.


                  I keyed the video as well as I could but transparency remains.


                  I precomposed the video after copying the video track so I wouldn't lose the attributes when they transferred to the pre-comp.


                  A new window opens that has the pre-comp in it.


                  The other tab has the original keyed video below the new pre-comp.


                  I don't understand whether I should be working with the pre-comp alone plus add a black solid under it or whether I should be working with the original video that has the new pre-comp ABOVE it in the timelines and add a black solid to THAT.


                  I don't have a "Take Matte from" menu. I know how the "whip" works but can't figure out which composition I'm supposed to be working in.


                  I can't tell if I'm supposed to apply the Matte Choker before or after I do the part I can't do anyhow because I don't know how to do it.


                  You're right about it taking mastery. But at this rate I can't even turn on the freaking lights.


                  I guess I'll just have to hunt around and look for some kind of tutorial on basic matte making or something. Seems to me it should be easier than this.

                  • 6. Re: Using Keylight 1.2 - I think I got it.
                    john_orban Level 1

                    Futzed around some more and I've got my black mask. I have too heavy a black line around the outside of my "talent" but this is not for prime-time...just a school skit...I'll twiddle with a few more controls and see if I can get it down a bit more.


                    Appreciate the comments...pointed me in the right direction.




                    • 7. Re: Using Keylight 1.2 - I think I got it.
                      Adolfo Rozenfeld Adobe Employee

                      Yes, John.

                      The trick we discussed could work well for small holes in the mask. Not for someone wearing, say, an entirely green scarf.


                      Maybe pushing the choking control would make the outline contract?

                      • 8. Re: Using Keylight 1.2 - I think I got it.
                        Adolfo Rozenfeld Adobe Employee
                        Seems to me it should be easier than this.


                        Basic keying is much easier than that.

                        The #1 thing you learned for the future is, never, never use the key color in the subject's clothes.

                        The complicated solutions we're discussing are for a complicated problem which shouldn't be there

                        • 10. Re: Using Keylight 1.2 - I think I got it.
                          Mylenium Most Valuable Participant

                          Also always keep that one rule in mind: As long as you get a clean Alpha somehow, nobody will care how it was actually generated, meaning that you can freely employ any adjustment and trickery to ramp up contrast between foreground and background no matter how strange it may make your footage look. Remember, that it's easy to recombine color and Alpha using Matte modes or effects like Set Channels/ Shift Channels/ Set Matte. In your case, probably some conversion to YUV colorspace could have helped to spread the range between the two greens before keying. Also, and don't get this the wrong way, consider using the other keying options like the Color Difference keyer. People too often forget about these options because they are under the wrong impression Keylight could give instant good keys with one click of the eyedropper...



                          • 11. Re: Using Keylight 1.2 - Whoa, dog!
                            john_orban Level 1

                            Whoa, man, I'm still a newbie...I don't even understand 1/2 of what you just said...I look at some of those menu items and my head starts spinning.


                            I'm watching tutorials like crazy but realize it's going to take YEARS for this stuff to sink in.


                            I finally got an acceptable looking video which I'd love to post, but can't because it's one of the kids here at school and I'd probably get in all kinds of trouble, but I have to admit it looks pretty darn good.


                            Very frustrating to know what you want, but not know how to do it.



                            • 12. Re: Using Keylight 1.2
                              michal717777 Level 1


                              I think all they want to know is how to invert the matte. Am I missing something here? How did you interpret their question? That's why I found this thread. It seems like a simple check box for invert on keylight would be a good idea. Right? Anyway, Creative Cow gave this answer:


                              Re: Invert Keylight Effect?

                              by Dave LaRonde on Jun 9, 2010 at 3:57:49 pm


                              Easy: pull the key, precomp the layer, then use the Invert and Fill effects in that order. Change the Fill color to whatever you want.


                              You precomp the keylight layer so you can use garbage mattes on it with no problems.


                              Dave LaRonde

                              Sr. Promotion Producer

                              KCRG-TV (ABC) Cedar Rapids, IA

                              • 13. Re: Using Keylight 1.2
                                john_orban Level 1

                                Hoo boy - is this a "blast from the past". That original post was in 2009. Don't even use Keylight anymore (unless Adobe bought them and incorporated the technology into CS5).


                                Trust me, I've learned my lesson - no green shirts against green screens! Yeah - inverted mattes and all that...


                                What a difference a couple of years makes, huh?