My friend Rufus Deuchler recently gave me a challenge. I started in video production working with virtual sets and chromakeying over a decade ago. I've used many different technologies over the years to remove green screens and blue screens, and found various techniques for preserving the original colors in the remaining video. However, I had never used Photoshop to do it before. It's actually quite easy using the new Adjustments and Masks panels in Photoshop CS4.
Let's start with a picture of Rufus, where the green has already been removed. Look at the color of the edge of the hair, and the side of Rufus's face. It has a green tinge to it.
Start by loading up the ESSENTIALS workspace in Photoshop CS4. This includes the Adjustments Panel, and the Masks Panel is in a tab in the same location.
Go to the Adjustments panel, and add a new Hue/Saturation adjustment layer. Click the check box to colorize. Set the saturation to about 65, and the Lightness to about 60. The Hue used will depend on the type of color spill in the original image. If you picture a color wheel, what we are doing is adding the opposite color to the image. So for blue spill, use a lemon yellow color - something around 60. For Green, use a magenta - something around 270.
Now, let's mask the color. With the Adjustment Layer still selected, go to the Masks panel, and click the button to Create a Pixel Mask. Click on Color Range, and in the Select drop-down menu, select Green. This will give us the start of our mask.
Now, go back to the Hue/Saturation panel, and play with the saturation and lighting. You want to add enough Magenta to the image to cancel out the green, but not so much that the hair turns purple. There may be areas that are not affected yet - that's because the mask isn't perfect. We'll fix that in the next step. For now, worry about the areas that are being affected, and get the saturation value in the right ballpark.
Select the mask in the Layers panel by clicking on the mask icon in the adjustment layer.
Select the paint brush, and set the brush color to white. Set the opacity to about 10%. Paint over any remaining areas where green is still showing in the hair or skin. For example, in this image of rufus, the right edge of his face is getting a touch of green spill that isn't currently being affected enough by the adjustment layer. Paint over this area. If you overpaint, and his face turns magenta, switch the brush color to black and repaint. Also, play with the opacity of the brush if necessary.
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