Tuesday, January 23rd, 2018

Complex Green/Blue Screen Keying – After Effects CS4


Well – since it’s Christmas Day, early AM, I thought it was appropriate to post this Santa composite, utilizing both Green Screen (for the background) and Blue Screen (for the foreground) all in one shot. This complex keying shot uses two passes with the Keylight chroma-keyer in After Effects CS4 to accomplish the “sandwich” of Santa between the two screens.

I first needed to line-up the green screen footage layer with the background layers used in this composite, so I set a guide on the edge of the door and moved/rotated the green screen footage to line up the edge of the blue panel with the guide. I then create a large feathered mask around the live action portion of the screen footage as a “garbage matte”.

I then use the Keylight keyer filter on the green background and fine-tune the settings to get the best possible key of the Santa character. (Oooh… he looks a little pissed here, doesn’t he?) 😉

Next I use the Keylight filter on the blue foreground panel and adjust to accommodate for the shadows from his hands, so the door shows through.

Lastly, I use the Levels filter to adjust the color of the keyed character to attain the best color and lighting for the composited scene.

You can see the before/after video of this process in the movie link below:
NOTE: YouTube screws up the first few seconds by over-compressing the video, but it clears up – just let it keep running!

To see this tutorial in step-by-step detail, you can get my new training DVD here: “Learning After Effects CS4” from PhotoshopCAFE.com


5 Responses to “Complex Green/Blue Screen Keying – After Effects CS4”
  1. Chris Foley says:

    That’s awesome Jeff. I think I’m going to pick up my copy of CS4 so I can do cool stuff like this too.


  2. Hi Jeff…this is close to what I want to do…
    is it possible to have two different full screen images show through in the green and blue areas? I have a video with both colors that I want to use for separate keys: water in the blue area, sky in the green area and they are interspersed.

  3. Jeff says:

    Hi Claudia –

    If I’m understanding you correctly, you want to replace the green/blue screened areas of your footage with full-screen video, right? Technically, when you’re creating a chroma key of any color, your’e basically just “punching holes” in the footage and revealing whatever is behind it. If you’re using a tool like After Effects, then I would approach it like this… create a Comp and then key only one of the colors first and reveal the water/sky. Then create another Comp, import your first Comp into it and repeat for the second color. Viola! You have two full-screen keys from one shot and didn’t have to pre-render anything! 😉

    Hope that helps. Contact me through my site if you need further assistance.


  4. Steven says:

    Hello Jeff. Quick question… Why is it that the blue screen was needed? maybe I am missing something, but couldn’t the same effect have been achieved just the same with a green screen in the back ground and fore ground? Or was it just a case of the fact that it would be more difficult to retain things like shadows of his hands while trying to get a good key on the background with two green screen elements?


  5. Jeff says:

    Hi Steven –

    The reason you need two colors in a shot like this is so you can maintain the division of foreground and background in your composite. You are correct in your assumption that in order to keep the shadows on the surface that the actor makes contact with, but still get a clean matte from the white fur on his costume, we need two separate colors. Had this been a character that had a broader range of colors in their appearance, this would have been more difficult to pull off as well.

    Thanks – Jeff

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