Buried at the base of the Layer Style dialog, the Blend If sliders are among Photoshop’s most mysterious and least understood compositing features. Given their extraordinary power, it’s a shame that more people don’t use them. In this Photoshop Workbench, I intend to demystify these sublime sliders.
To explore the Blend If sliders, we’ll use a three-layer document. The bottom layer is a photograph with a broad range of tonal values. The second layer is a grayscale step wedge. The top layer contains the entire color spectrum. We’ll work with two layers at a time, sometimes turning layer visibility off and on.
Their are three ways to access the Blend If sliders:
1) Choose Layer>Layer Style>Blending Options.
2) In the Layers panel, double-click in the empty space to the right of a layer name.
3) Click on the Add a layer style icon at the base of the Layers panel and choose Blending Options.
At the base of the Layer Style dialog is a box labeled “Blend If.” By default, the pull-down is set to Gray. Within the pull-down, there are also Red, Green, and Blue options.
Beneath the Blend If pull-down are the blending sliders. The “This Layer” sliders are used to make parts of the active (top) layer invisible. The “Underlying Layer” sliders are used to visually “pop” parts of the underlying layer through the top layer.
During this lesson, you’ll notice that moving any of the sliders creates a noticeable “tear” in the picture. In most cases, it’s more desirable to produce a smooth blending transition. To achieve this, at the very moment when tearing occurs, hold Option (PC: Alt) and grab the inner half of the slider to split it in two. Continue to drag this half to create a smooth transition.
To illustrate all that these sliders offer, we’ll first explore them by blending the “Grayscale” layer with the underlying picture. Then, we’ll blend the “Colors” layer with the underlying picture.