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First you need to get yourself some footage with a Blue (or green) Screen
Import into a Combustion workspace. Or you can open the footage as 2D composite or a Discreet Keyer, which will open the footage and automatically assign a keyer to it.
Combustion will, by default, look at the footage as its RGB value and automatically detect the color that is most predominant in the shot as assume that the color is the screen. It will pull that as the matte.
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However, RGB may not be the best color process to pull from. Make sure that Store is toggled on and go to Buffer#2. Combustion will store the RGB pull in Buffer#1 and change the Keyer Mode to YUV. Store that in #2 and move onto #2 and change the mode to HLS. Repeat this for each of the keyer modes to see which process is pulling the matte in the most effective way.
Also check the mattes to see how they look. Note* I’m not sure why HLS and RGBCMYL has mattes that look like they are inverted – waiting on an answer for this.
(Keyer_RGBMatte.jpg, Keyer_YUVMatte.jpg, Keyer_HLSMatte.jpg, Keyer-RGBCMYLKatte.jpg)
I chose YUV because it seems to have the subtlest interpretation of the matte. But in all the processes, the blue head does not pull.
Click on the “plus eyedropper” next to the Threshold and Cntl+Drag over the blue areas in the head. The variations of blue are added to the key.
Combustion also lets you know what color ranges are being keyed. Before the threshold addition, the color threshold was the color of the screen. In each of the Y, B-Y, R-Y channels a range is set for the chosen key color. The cyan line shows the chosen color. The distance between the cyan line and the two yellow lines is the softness range – how quickly the key falls from 100% keyed to 0%. These lines can be explicitly moved to make subtle adjustments to what values are keyed.
After I added the colors of the mask, this is what the color sliders look like.
The ranges have split apart. The area between the two cyan lines are the ranges that are now included in the key. The softness ranges have also changed.
So, the matte looks like it coming along well. But if we look at the matte – there are still problems.
The matte for the shirt is still very thin (which we will fix later), and there are stray marks above the neckline. What to do? Oh the humanity!
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