Photoshop CC: The Missing Manual, 2nd Edition

Layer Blending

In Photoshop, blending refers to the way colors on one layer interact with colors on other layers. The program gives you some pretty powerful blending options in the form of layer blend modes, advanced blending, and “blend if” sliders. You can do some amazing stuff with these tools, as illustrated in the quick exposure fix described on Fixing Exposure with an Adjustment Layer and its Mask. However, since blending is most handy when you’re combining images, these tools are covered in depth beginning on Layer Blend Modes.