Now there’s a huge subject, and actually I don’t want to talk about colors in general just one particular point, or actually one particular color, black. I took a black and white photography class a few years ago. In the class the teacher said that Ansel Adams always felt it was important to have a pure black and pure white in every print. During the class I never tried to get a pure black in my prints. I didn’t think it was important. Since then I’ve grown in my understanding of photography. Now I understand the importance of pure blacks in a print. When you set a black point in photoshop using curves it can take care of a lot of problems. The first thing I notice when setting a black point is it takes care of a lot of color cast issues. The second thing with setting a black point it increases contrast. With increased contrast details become more defined and haze in the print clears up (prints pop). Setting a black point to black is the fastest way to improve a print.
To set black using curves in photoshop is fairly easy. In the navigator window change to info. Then bring up the layers window and create a new curve layer (layers another time). The new layer button is the half black and half white circle at the bottom of the layer dialog. Choose curves from the menu that pops up. From the window that pops up click on the eyedropper with the black dropper section. Finally move the curser around areas of the image that is or should be black (watching the info box for numbers that are in the teens or less if possible). When you’ve found a black area click on it. The results should be immediate. Give it a try.
-Philip