How to Use Photoshop's Blend If Feature

Photoshop offers a number of techniques for blending colors between layers. This can be very useful for filling a jar with water or floating fish in an aquarium. Sometimes, however, Photoshop's more visible blending modes just don't do the trick. When these fail, you can resort to Photoshop's little known Blend If feature.

Instructions

1. Arrange your Photoshop layers so that the blended layer is on top of any colors or image areas you want to bleed through." Open the Layers palette and double click on the layer. The Layer Styles dialog will appear. Check "Preview" to watch your changes appear as you adjust the dialog.

2. Select the channel with the colors you want to mask or blend from the Blend If options (usually it will be gray). Option (Mac) or Alt (PC) click the white highlights slider in "This Layer" and drag to the left to split the control into two handles. Drag the leftmost highlights slider to the left to set the bottom range of white and midtone areas you want to mask. You will see the colors from the underlying layers appear in the document window.

3. Drag the rightmost highlights slider to the left to mix some highlights back in. Continue to tweak until the white areas are sufficiently transparent.

4. Split the shadows slider by clicking the "Option/Alt" key. Drag the handles to the right to mask the black and dark gray shades in the layer.

5. Mix underlying colors by choosing the color channel from the Blend If menu. Adjust the shadow and highlight sliders in "Underlying Layer" to add shades of that color channel back into the overall image. With a little experimentation you will learn to blend or mask any colors in a layer.

Tips & Warnings

• If you want to make a water glass or bottle appear to be transparent, work with two copies of the glass layer. Place one beneath the layers to be used for contents and one above. Apply the blend effects to the top layer to keep the reflective colors in the glass.

• You can still reset a layer's basic blend mode to increase the layer blend options. The advanced sliders affect the distribution of colors in the layer, the blend modes how the colors mix between layers.