ZMatte

Digital Film Tools has created a very easy-to-use plug-in—not to mention a more affordable solution for most chroma keying purposes. As with other more-expensive keying plug-ins, you can use it to key out most blue and green backgrounds, including a blue sky. zMatte has tools to quickly adjust the matte to eliminate uneven backgrounds. This example combines a scenic city image and a freeway sign against a blue sky (Figure 9.19).

Figure 9.19

Even a blue sky can be keyed out easily with the zMatte plug-in.

Figure 9.19

Even a blue sky can be keyed out easily with the zMatte plug-in.

Note: To try a demo of zMatte, visit the Digital Film Tools website at http://www.digitalfilm-tools.com/html/zmatte_download.html.

When I applied the zMatte plug-in to the sign layer by choosing Effects > DFT zMatte > zMatte and changed the View selection from Output to Matte on the Effect Controls palette (Figure 9.20), the layer turned to a reversed black-and-white matte in the Comp window.

Figure 9.20 I selected View Matte to see how much the matte needed to be adjusted to get a clean key from the sky.

I then spun down the Primary Matte arrow and opened the Background and Foreground sliders and dragged the sliders to fill in the background and foreground areas in the matte (Figure 9.21). I adjusted the Background to 30.0 and the Foreground to 20.0, which looked like a fair balance between the two.

Figure 9.21 I adjusted the Background and Foreground to get a clean key but a solid mask.

Figure 9.21 I adjusted the Background and Foreground to get a clean key but a solid mask.

I set the View back to Output and checked that the composite was nice and clean. However, there was still a bluish hue to the metal on the signpost that looked out of place against the city. If it had been actually photographed as a freeway off ramp in the scene, it would have had a warmer tone to match the background colors of the city.

I was able to adjust the color without affecting the matte in the foreground layer. I spun down the Color Correct arrow, opened the Red and Blue settings (Figure 9.22), and used the sliders to reduce the amount of blue while increasing the amount of red in the layer. Because the green level was already where I wanted it, I left that alone. The final composite shared a balance between the two light sources.

Figure 9.22 I was able to make color corrections with the plug-in without affecting the matte.
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