[DonRotolo]

Let's say you want to filter OUT the color yellow. You place a Yellow colored piece of something transparent over the thing doing the looking, and the yellow material makes all things that are yellow appear to be the same as things that are white.

Try it. Find something colored and transparent, and look at the world through it. Green is especially weird outside.

You may note that the "filter" doesn't exactly cancel out the color, you can tell a difference between the colored item and a white item. That is because the color of your filter is not exactly correct.

People in the photography world use colored plastic sheets, thin like an overhead transparency, available in literally thousands of different colors, for exactly this purpose. Go to a high-end photography store - not a chain store - and someone will surely send you in the right direction.

Hope this helps

Don