Tuesday, April 26, 2011

Green Screen For Photographers

Chris Borgman is a New York-based photographer with a knack for crafting wild and whimsical images.
By William Sawalich, Photography By Chris Borgman Published in Shooting
"What's the difference between masking and keying? Think of it this way: You mask the background, and key the subject. The same thing is happening in both instances; it's just semantics, I guess."
"What's the difference between masking and keying? Think of it this way: You mask the background, and key the subject. The same thing is happening in both instances; it's just semantics, I guess."


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Borgman, expert though he is, still starts every masking process with trial-and-error experimentation. He tests each of his favorite masking plug-ins on a different layer and keeps only the best result. For subtle touch-ups around tricky edges, he uses special brushes, which he finds online, with shapes that create a more natural blend. For the finishing touches, he smoothes the edges of the mask and addresses color and shadow issues.

"When it's time to get picky about the mask," he says, "I start with a blur/choke technique, then repeat. This is done by selecting the layer mask and applying usually a 1-pixel blur. Then select levels and move the triangles to one side to choke; moving to the other side will spread. This is the old-school way; Photoshop has probably got something in the Selection Refine tool that does the same thing, but I do what I know works. I repeat the process with a 0.5-pixel blur and less movement in Levels. Don't overdo it; you want to tighten the mask, but not sharpen it. It's the fuzzy pixels between the subject and background that make a seamless merge. Too sharp an edge, and it looks obvious.

"To get rid of any color from the original background," he continues, "if it doesn't match perfectly, I try two techniques. One is to use the Hue/Saturation filter to isolate the color in the hair and change that to match the new background. That probably works some places, but not everywhere. Next, I add a new layer above the model and turn it to Color mode. I then select a color of hair right next to the background color and literally brush away that original background. This is why I don't use white—no way to brush it out, but turning blue or green to brown is easy.

  • Canon EOS 5D Mark II
  • Canon 24-105mm ƒ/4L
  • Tamron 28-75mm ƒ/2.8
  • I rent medium-format when needed Panasonic GH1 (hacked) for video
  • Dynalite (love the size), AB ring flash, some old Novatrons—I'll use anything that flashes
  • iMac 27-inch i7
  • Old 17-inch Apple monitor, for menus
  • Two Western Digital MyBook SE IIs (2 TB)
  • Logitech MX310 mouse (fits like an old glove, and I've always hated Apple's mice)
  • Wacom Tablets
  • Two Epson R1900 Printers
  • UltraPro Gloss and Satin Paper from Red River Paper
"You can get a perfect mask," Borgman adds, "but if your model was shot with daylight-balanced strobes and your background was shot close to sunset, you've got some real tweaking to do. In that situation, I'd probably cool off the background a bit, then warm up the model until it looks convincing. Probably the most important aspect of compositing is shadows, which tie one element to another. If the shadow isn't convincing, then all your efforts are lost. In compositing, you have to pull the shadow from your studio shot or create one from scratch. Many of my students have had a hard time wrapping their two-dimensional photography minds around a three-dimensional idea. Shadowing—that's a whole article by itself."

Chris Borgman is a New York-based advertising and editorial photographer. He also teaches photography and advanced Photoshop techniques at the Miami Ad School in Florida. "If you want to learn advertising photography in its truest form, this is the place." Go to chrisborgman.com.

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