Layer Blending Options, Part 1

MonkeyLek · September 30, 2003 9:34 am

In the Layer Style dialog box, up near the top, is the under-utilized Blending Options. Learning the basics of layer blending can take your images to the next level, and save you quite a bit of time with certain jobs. In this basic look at the simple (yet somewhat daunting) dialog box and the layer blending options, we'll show you the basic controls and options. First, let's look at the dialog box. Graphic1251.jpg To the left is a list of the Layer Style dialog box panels. Clicking on Blending Options opens the panel shown. To the right are the standard buttons and the Layer Style preview button. The middle section contains the options themselves. In the General Blending section, you'll see the Blend Mode and the Opacity slider. Changes made here are immediately reflected in the Layers palette, and changes made to blending mode and opacity in the Layers palette are shown here. The Advanced Blending section holds some incredibly powerful tools. Fill Opacity: This slider allows you to reduce the opacity of the content of a layer without reducing the opacity of effects applied to the layer. Drop shadows, bevels, and several other effects retain the layer's general opacity (set in General Blending or the Layers palette). Graphic1252.jpg In the Layers palette, you'll see that the heart shape (at the top of the layers palette) is actually a shape layer with effects applied. If no effects were applied and the blending options were set to the defaults, a larger, flat, boring red heart would appear. However, a stroke has been applied, as well as a bevel and a drop shadow. Below, in the Layer Style dialog box, you can see that the Fill Opacity has been reduced. This affects only the heart's red fill, not the beveled stroke. (If we wanted the stroke to be transparent as well, we would use the opacity slider in the general Blending area or the Layers palette.) Channels: You can choose to blend all channels, or specific channels. Knockout: The specified layer will be used to hide the underlying layers. (Sort of a reverse layer clipping mask.) The choices are None, Shallow, and Deep. If None is selected, there is no knockout. When you choose Shallow, the layer's pixels will knock out underlying pixels of layers in that same layer set. If there is no layer set, the knockout extends downward in the layers until either it hits a background layer or reaches transparency. In the following image, notice that the heart has been moved into Layer Set 1, with the type layers. With Knockout set to Shallow, the heart knocks out all of the layers in the set, but only the layers in the set. Graphic1253.jpg With Knockout set to Deep, as shown below, the knockout goes all the way to the Background layer (or, if no background layer, all the way to transparency). Note, however, that Set 1's blending mode is Pass Through in the Layer's palette. When the layer set's blending mode is any other, the knockout stops at the bottom of the layer set, even when Deep is selected for a specific layer. Graphic1254.jpg In addition to layer sets, knockout can be affected by clipping groups. Blend Interior Effects as Group: When selected, any layer effect that ranges inside the actual artwork on the layer (Inner Glow, Satin, Overlay) is blended with the artwork before the artwork is blended with the rest of the layers. Blend Clipped Layers as Group: Layers within the selected layer's clipping group (if any) will be blended together before they are blended with other layers. Blend If: When Gray is selected, all channels are blended using each pixel's luminosity or brightness value. Alternatively, you can choose to blend the color channels individually. The sliders control what pixels blend, and how much, between layers. In this figure, the upper layer (golden chains) is active and the upper slider is set to exclude the lighter pixels on that layer. Using the Gray option, the lightness values of each pixel is evaluated. As shown, any pixel on the upper layer with a brightness of more than 200 will not be blended, and therefore will be rendered invisible. Graphic1255.jpg By holding down the Option/Alt key, we can split the sliders to define a range of partially-blended pixels. This creates a smoother blending. Graphic1256.jpg In addition to the value shown above for Gray, we could also blend the individual channels. (This does not affect the slider positions for Gray.) If we adjust the underlying image to force blue to blend, areas with blue pixels in the lower layer will show through the upper layer, as shown here. Graphic1257.jpg You can even drag the light and dark sliders past each other to create fantastic blends. In this example, we achieve the desired effect of "ghostly golden chains" by reversing the sliders. Graphic1258.jpg Reversing the sliders for the heart layer also changes the look of the underlying pattern in Hippie Haven's final version. Graphic1259.jpg In Part II of this exploration of Layer Blending Options, we'll look at some particularly practical applications.
Previously featured Planet Photoshop articles, including the other Brushes Palette tutorials, are archived under Featured Columns. Special thanks to for allowing us to reprint their Photoshop tutorials here at Renderosity. You can e-mail Pete Bauer, the author of this article, at

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