Removing and Replacing Color
Remove Color is easy to understand and easy to use. When you select it from the Enhance, Adjust Color submenu, it simply removes all the color from your picture, converting it to grayscale, but without changing the color mode to grayscale, too. Why is that important? Because, having turned the picture to grays, you might want to paint back some colors, perhaps different ones, or paste things in color on layers over it, or who knows ? It's your picture. By the way, you can use the Remove Color command on a selection, removing color from just an area of an image. You might select the background and remove the color from behind a person, for example, to make her stand out in an interesting way. This technique is used in advertising all the time to draw attention to products.
Replace Color, on the other hand, is in my opinion the least comprehendable dialog box in any form or version of Photoshop. You can use Replace Color to replace one color in an image with some other color. For example, you can change all the yellow roses in a photo into red ones, or try out a new paint color on your house. Still, the dialog box is a bit intimidating. I've taught you an easier way to do it, but in case you really want to try out Replace Color, the following task will show you how.