PHOTOSHOP TIP: A Trick with Luminosity
by Charles Cramer

If you are working in RGB, and are using a curves or levels adjustment layer to lighten or darken your image, you'll probably notice a change in the color, too.

Unlike a LAB file, where the lightness/darkness and color information are stored in separate channels,

in RGB, each channel controls both--they're intertwined.

So, when you lighten (or darken) an image, you'll also be changing the color. Sometimes this color change can help the image--sometimes not. I usually check to see whether I like the effect--it's easy to do!

Change the mode of the curves or levels adjustment layer from "normal"

to "luminosity"

Luminosity mode makes the curve or levels adjustment layer work only on the lightness/darkness of the image--and not on the color.

Text and photos ©2004 Charles Cramer, All Rights Reserved. This page may not be reproduced without the permission of the copyright holder.