Seán Duggan: Layer Blend Modes, Part 1
Mar 2014 11

Blending Modes in Adobe Photoshop are some of the most powerful ways to quickly transform an image, either for creative explorations, or for more practical purposes that address fixing a specific issue. Most people are probably familiar with blending modes from the Mode menu at the top of the Layers panel, but they also make appearances in other areas of Photoshop, such as options for any of the painting tools, and as key elements in the Apply Image and Calculations dialogs.

Understanding how blend modes work and knowing the general result you’re likely to get will help you use them more effectively. In part 1 of this article, we’ll take a look at some essential blend mode concepts, and then in part 2, I’ll present several examples of how certain blend modes can be used for specific effects.

Under the hood, Blend modes are essentially just math. When it comes to layers, blending modes control how layers interact with each other by taking the values of pixels on the top layer (the “blend” color), as well as the values for the underlying pixels (the “base” color”), running an equation with those numbers and displaying the result.

The changes you see on screen are due to the fact that the new numbers created by the equation are being used to display the image. Fortunately, you don’t need to know the actual math that is doing all of this; to get started using blend modes effectively, you just need to know what to expect in general. As you use them more, you’ll become more familiar with how they work on certain types of images and you’ll learn how to control them and, most importantly, use them to the address very specific issues.

Blending modes are presented in the Mode menu of the Layers panel in a definite order and are grouped together in specific arrangements (in order to see this in your version of Photoshop, you need to have a file open with at least two layers). The modes in each section generally will produce a similar result. The big caveat here is that blend modes affect the image on a per channel basis, and this can sometimes create unexpected results.

General Results

In very broad strokes, here’s what you can expect: The section that begins with Darken will generally produce a result that is darker that what you start with, and dark values will be emphasized.

The section that begins with Lighten will produce a lighter result, and lighter tones and colors will be emphasized.

The modes beginning with Overlay will produce a result that increases contrast, sometimes pronounced, sometimes subtle, and sometimes very extreme.

The modes beginning with Difference are comparative and are typically create the most exaggerated effects, such as the color negative view created by Difference and it’s lower contrast cousin, Exclusion.

The final group of blend modes beginning with Hue are component-oriented, meaning that they will emphasize the color components of hue, saturation and luminosity of the active layer. In the case of Color, the components of both the hue and saturation of the active layer are applied. In the example below using the Luminosity mode, the luminosity (brightness) is coming from the sky window layer, with the color and saturation from the underlying music/ferns layer.

Neutral Colors

Most of the blend mode groups have a neutral color that has no effect on the blend. When used with the right blend mode, neutral colors disappear, as if that part of the layer was totally transparent. Knowing the neutral color is important when working with blend modes because it can be used very effectively in combining images, or controlling how a blend is applied.

The neutral color for the Darken blend modes is White. Any white areas on a layer will not be visible when these modes are used.

The neutral color for the Lighten blend modes is Black. Any black areas on a layer will not be visible when these modes are used.

The neutral color for the Overlay blend modes is 50% Gray. Any middle gray areas, specifically 50% gray, on a layer will not be visible when these modes are used.

Blend Modes Shortcut

If you’re curious how different blend modes will affect an image you’re working on, give this cool shortcut a try: Hold the Shift key down and repeatedly tap the + key to move down through the list of blend modes. The reverse direction and go back through the list, use Shift – (minus).

In Part 2 of this article, I’ll explore some examples that show how blend modes can be used to create very specific effects, either for creative treatments or to address and fix very specific issues in a photo.

Seán Duggan is a fine art photographer and the co-author of Photoshop Masking & Compositing, Real World Digital Photography, and The Creative Digital Darkroom. He leads workshops on digital photography, Photoshop and Lightroom.