Colorizing a Grey Background with a Bad Mask

Quite often, you do not need a perfect mask in order to colorize a grey studio background. The purpose of the mask is to protect the subject from color spill from the background. But, is this always desirable? Let us start with a studio capture of Michelle Nguyen:

Starting image of Michelle.

Starting image of Michelle.

I wanted to change the grey seamless background to a bluish color. To accomplish this I added a color layer over Michelle's image, changed the layer blending mode of this color layer to Vivid Light (which lets Michelle show through a bit), then added a very quick, as well as imperfect, layer mask to reveal Michelle:

The strands of blue hair indicate a poor mask.

The strands of blue hair indicate a poor mask.

In this instance, this imperfect layer mask is black over most of Michelle to keep the blue color off of her, and white around the edges to reveal the blue color. In a real studio situation with a blue background, it is entirely possible that there could be some color splash coming from the background from behind Michelle and illuminating her edges. This can easily be simulated by using a soft, 20% opacity white brush to paint on the mask anywhere some of this blue light splash is desired. Here is the result:

Final image of Michelle.

Final image of Michelle.

This technique is much easier than using colored gels in the studio, and has several advantages:

  1. The color spill can be painted exactly where it is wanted.
  2. The color of the background can be changed to any color - at any time.
  3. You do not have to be a master at masking hair.
  4. The same grey seamless can be used over and over to achieve a multitude of colored backgrounds.