Adobe Photoshop is a great program, but there are so many features and options that it’s easy to get confused or even dismiss something helpful because you aren’t sure what it is or how it works. Further complicating things is the fact that the available “Help” menu doesn’t always teach you how or why the features work the way they do.
What I’d like to explain here is how the blending modes work in Photoshop. This isn’t a step-by-step tutorial on how to replicate a nifty swirling ethereal glow around your subject, or realistic starship exhaust. This is an item-by-item description in plain English of each mode and how it works.
I assume that you understand the basics of layers and layer properties, channels, and color modes. If you’re still new to Photoshop this might be a little hard to follow, but if you still want to forge ahead, I will try and keep it simple.
A background layer is the last layer in a Photoshop document. Nothing can go behind it, and its blending mode can’t be changed. The background can contain pixels, but every layer above the background will affect the pixels of every layer beneath it including the background. Layers can range in opacity from nearly transparent to completely obstructing your view of what lies behind. If it helps you to understand by doing as you read this, then by all means make a new Photoshop document. Just make sure you are creating on a layer other than the background or it won’t work.
A blending mode is a reference to how the pixels being applied will interact with the pixels they are being applied over. In other words, you might experiment with a single layer’s blending mode and not notice any difference between one and the other because there are no pixels beneath for the layer to interactively blend with. Confused? Think of it this way: Each layer is like a clear sheet of plastic wrap suspended above a background layer. If you smear some opaque paint on any of those layers, it will cover up everything that is on any layer beneath it (because it’s opaque, so you can’t see through it). You could have the Mona Lisa right beneath that layer, but you’d never know it by looking. But if you could magically change the property of that layer and control the opacity of the paint (similar to some blending mode options) you would begin to see the subsequent layers showing through. The manner in which the translucent layer changes the appearance of the layers beneath it is analogous to a layer blending mode.
That’s about as simple an analogy as I can think of. Unfortunately, a simple analogy won’t get you very far in a multiple-layer, multiple-blending mode document because so many different things are happening at once that you lose track of what layer is influencing which color. To complicate it even further, tools which apply color to your document have blending modes as well. But don’t worry–they have the same net effect IF you keep the following in mind: The blend mode of any brush will relate to the pixels of one layer the same way a layer blend mode works across multiple layers.
Confused? Take a look at this image.
