This project from Kevin Winzeler was really fun to work on because the final output was black and white.
The fun of finishing in B&W is that you can use the color channels to remap the luminance. Basicly in B&W, different colors apear as lighter or darker shades of gray.
You can see in this little chart what it looks like when you suck out the color. Magenta turns almost white.
So by tilting the hue of a particular color channel, you can darken or lighten elements in the image. Lips for instance, can be darkened by making them blue.
Black and white hue-bending can best be seen in the shot(numbers 12 and 13) of him holding a frame where you can barely see the paint job in the plain B&W. The light green paint on the front of the frame wasn't showing up. In color it really popped, but in B&W it looked white. The shot right after is a silver frame which also looks white. The two shots would appear as a jump cut in the middle of the same shot of him holding a white frame. So to fix it, I tilted the hue of the green toward blue to darken the paint so it would have the same contrast as the color version.