Blending modes are one of the fastest ways to experiment with imaging effects in your Photoshop files. Think of them as preset functions that apply a range of imaging effects that standard Photoshop commands can't touch. The basic function of a blending mode is to compare two sets of pixel data and combine them in different ways. Although I could write an entire chapter on exactly how these options work, 99 percent of Photoshop users simply experiment until they get an effect they like.
Blending Modes in Layers Palette
Select Window, Layers to open the Layers palette. The Blending Mode drop-down menu is at the top of the palette. Highlight a layer tile in the list and click and hold the menu to select one of the modes. The contents of the selected layer are compared with all the layers below it to achieve the result. Keep in mind that you cannot apply a blending mode to the Background layer.
Blending Modes in Paint Tools
You can select any of the paint or shape tools and apply them using the blending modes. With the tool selected, select an option from the Mode menu in the Options bar. This approach to modes compares the values from the paint color or source data (if you're using the Clone Stamp or History Brush tool) with the underlying image. Blending modes are available with the following tools: Airbrush, Paintbrush, Clone Stamp, History Brush, Gradient, and Shape.
Blending Modes with Filters
After applying a filter, select Edit, Fade <filter name>. The Fade dialog box opens with an Opacity slider and a Mode menu. Select the desired mode from the menu and click OK to apply the effect. This approach to modes compares the original image data with the results of the filter effect.
Blending Modes with Fills
Select Edit, Fill to launch the Fill dialog box. Select Foreground Color or Background Color from the Use menu and then select the desired blending mode from the Mode menu. If you want, you can enter a percentage value in the Opacity text box to apply the mode with a degree of transparency. This approach to modes compares the current foreground or background color with the image.
Blending Modes with Pattern Fills
Select Edit, Fill to launch the Fill dialog box. Select Pattern from the Use menu and select a pattern preset from the Custom Pattern list. Choose the desired blending mode from the Mode menu. If you want, enter a percentage value in the Opacity text box to apply the mode with a degree of transparency. This approach to modes compares the pattern values with the image.
Blending Modes with History
Follow the steps in Part 8, Task 4, "How to Use the History Brush," to set the History source in the History palette. Then select Edit, Fill to launch the Fill dialog box. Select History from the Use menu and select the blending mode from the Mode menu. If you want, enter a percentage value in the Opacity text box to apply the mode with a degree of transparency. This approach to modes compares the selected history state with the image.
Blending Modes with Tone and Color Adjustments
Because a blending mode requires the comparison of two sets of data, it's not possible to apply modes when using the color and tone adjustments found in the Image, Adjustments menu. However, you can create an adjustment layer and apply a blending mode to that layer as described in Step 1. This achieves the same result and also provides the flexibility of being able to hide or move the layer.
Blending with the Liquify Command
You can also fade and blend the Liquify command. After applying the Liquify command (Filter, Liquify), select Edit, Fade Liquify to launch the Fade dialog box. Select the desired mode and opacity and click OK.