Blending Modes

Want to win some bets at Photoshop World? Ask your buddy to name all of Photoshop's blending modes. Odds are, he or she won't know all 21 of them. That's right, 21 (twenty-one) blending modes! (Of course, if he or she visits Planet Photoshop, don't offer the wager.)

Be careful how you phrase this challenge. Don't qualify the bet by saying "layer blending modes." A lot of knowledgeable Photoshop users can come up with all 17 standard blending modes. Many of them will even remember the 18th blending mode, Behind, found with the painting tools.

If he or she has really been paying attention, the blending mode Clear might be listed. It's found with the Paint Bucket, the shape tools (in Create Filled Region mode), the Photoshop 5 Line tool, and the Fill command.

All right, well, that's 19 blending modes. What about numbers 20 and 21? You'll have to look hard for them. The menu commands Image> Apply Image and Image> Calculations are the secret. Buried deep within their dialog boxes are the blending modes Add and Subtract.

The blending modes Add and Subtract are found only with the Apply Image and Calculations commands.

So now that we know how many there are, what are blending modes? In a nutshell, blending modes are used to determine the interaction of two color values for a single pixel.

Two layers may have different colors for the same location (pixel) in an image.

A painting tool may add a color to a pixel that already has an assigned color value.

Multiple color channels may be used to produce a single color value.

When talking about blending modes, we normally use three terms:

The base color is the original color of a specific pixel.

The blend color is the color being applied.

The result color is the end product of the interaction between the base and blend colors. Changing the blending mode can have a substantial impact on the result color.

For a quick look at what blending modes do, lets see some examples. In the following image, the text layer has a blending mode of Normal. The pixels on the top (type) layer do not interact with the pixels below, they simply block them (depending upon opacity settings).

In this image, the only change that has been made is a switch of blending modes for the type layer. It is now set to Screen.

Changing to the Exclusion blending mode creates a much different look.

Notice how in the Screen and Exclusion blending modes the text's areas of solid color change according to the color beneath. In these examples, the colors found in the image of the bear are the base colors, the color values of the text (with bevel and drop shadow) are the blend colors, and the colors you see when the two are mixed are the result colors.

Because the change is being made to a layer's blending mode, everything on the layer is affected. In the case of the type layer, the layer effects (bevel and drop shadow) are affected.

Keep in mind that layer blending work downward the blend color must always be above the base color to create a result color. And remember that the reversing layers and blending modes can change the result color. In this image, the bear layer has been moved above the type layer. The type layer's blending mode has been returned to Normal, and the bear layer's mode is Exclusion. Note the difference between this image and the previous image.

In the next column, we'll start describing the individual blending modes and how each works.