What is color spill?

After you've created a mask in Primatte, you may see a colored tinge around the foreground image. This fringe is called 'color spill'. Color spill describes areas of your foreground subject that have absorbed or reflected color from the background. This often happens during the shooting process and needs to be corrected afterwards.

TOP: This fringe is also called 'green spill' or 'blue spill', depending upon the color screen you've used.

The spill removal process.

Any color tinge will be especially noticeable in semi-transparent areas, like wispy hair and materials such as glass and water. You need to remove spill in order to create a natural looking composite. Otherwise, your composite will look 'cutout' and fake.

During the removal process, you want to be conscious of any tradeoff between removing spill versus maintaining color fidelity. Primatte gives you a dozen ways to remove this spill without losing details that you need to keep. [more]

A tinge of blue is noticable in the model's hair. Primatte's simple 3-step process immediately removed the blue background screen. Now we need to deal with the color spill that is left over.

Here we've used two of Primatte's spill removal tools. The 'Spill Minus tool brought down the blue tones in the model's hair. Then the 'Restore Detail' brought back lost, delicate hair strands.

Dynamics of color spill.

How does spill occur? Basically, light bounces off the screen behind your photographic subject. This makes the background a light source essentially. That light throws a color on the subject.

If you threw a ball against the wall, the ball would bounce off and hit another wall. That's physics. In the process of light bouncing, the wall absorbs all the other colors besides itself, then casts off its own color light. If the wall is blue, the wall absorbs all the other colors that are cast by the lights around it, and bounces back only blue.

Think about it this way: If you have a red gel over a light, the light shines red. This is because the gel absorbs all the other colors but red, and lets only the red through. Oten it seems that you are coloring the light. In fact, you're actually removing light. This is a negative rather than a positive process.