When it comes to learning Photoshop, believe it or not, there's really only a handful of things you absolutely, positively need to know. Sure, Photoshop is a massive program that only seems to get bigger and bigger with each new version. But do you really need the latest and greatest version of Photoshop with all its bells and whistles in order to complete most of your day-to-day photo editing tasks?
Adobe would like you to think, "Yes, absolutely!!", but chances are, more often than not, the answer is no. With just a little knowledge and a few basic skills, you can usually accomplish most of what you need to do. Even though each new version of Photoshop comes with new features, new options and new toys for us to play with, the core skills you need to have are the same in Photoshop CS3 as they were back in Photoshop 3 when Adobe first introduced layers into Photoshop.
So what are these core skills? Knowing how to make basic selections is one of them. Knowing how to use and work with layers in Photoshop is definitely one of them. Understanding how layer masks work is very important. And knowing how and when to use layer blend modes, which just happen to be the topic of this discussion, is absolutely essential.
What Are Layer Blend Modes?
Quite simply, layer blend modes give us different ways for a layer to interact with, or "blend" with, the layer or layers below it. Without layer blend modes, the only real way we have of blending layers together is by reducing the opacity (or fill) of a layer, which usually doesn't give us very interesting results. But with blend modes, not only do they unlock a world of creative possibilities, especially when we combine them with layer masks, they can also be extremely helpful when it comes to editing, retouching and restoring photos, and they can save us a whole lot of time!
Of course, as with Photoshop itself, you don't need to know everything there is to know about layer blend modes in order to use and benefit from them in your daily work. As of Photoshop CS2, there were 23 blend modes in total (including the default "Normal" mode), and Photoshop CS3 adds two more to the list for a whopping 25 blend modes to choose from! With names like 'Dissolve", "Color Dodge", "Linear Burn", "Difference", and "Exclusion", it's enough to leave anyone scratching their heads wondering what does what and when to use which.
Here's a little secret. Okay, so it's not really a secret, but let's pretend it is since you seemed to perk up a little bit there when you thought I was about to tell you something no one else knows. As I just mentioned, you don't need to know everything there is to know about all the different blend modes. In fact, when it comes to day-to-day photo editing work, there's really only five blend modes you need to know. That's right, not 23 or 25, just 5! What are they? Multiply, Screen, Overlay, Color, and Luminosity. Understand how and when to use these five blend modes and your life of photo editing with Photoshop becomes a whole lot easier.
Where To Find The Layer Blend Modes
Before we get into what each of these five blend modes does and why they're so important, we should probably learn where to find them. If you think they're under the Layer menu at the top of the screen, well, good guess but no. Actually, that would be a bad thing, since you'd always be dragging your mouse up to the Menu Bar any time you wanted to change the blend mode of a layer. Fortunately, Adobe realized we're all a bit too lazy for that so they made things very easy for us. You can access all of the blend modes from a drop-down list in the top left corner of the Layers palette. By default, the "Normal" blend mode is selected:
One important thing to note here is that if you look at the screenshot above, you'll notice that I've gone ahead and made a copy of the original Background layer (by pressing Ctrl+J (Win) / Command+J (Mac)) and that I currently have the copy, named "Layer 1", selected. That's because Photoshop treats the Background layer differently from all other layers and it doesn't allow us to change the blend mode for the Background layer. If you're following along on your own and notice your blend mode drop-down box is grayed out, it's most likely because you only have one layer in your Layers palette and it's named "Background". To access the blend mode list, you'll need to either make a copy of the Background layer or you'll need to rename the Background layer.
When you click on the small, down-pointing arrow beside the word "Normal" and the drop-down menu appears showing you a list of all the blend modes, it may seem at first like there's no rhyme or reason to it, especially when you're not sure how each of them works. I'm using Photoshop CS2 here which has 23 blend modes to choose from, and as I mentioned earlier, Photoshop CS3 adds two new ones for a total of 25. If you look closely though, you'll see that the blend modes are actually divided up into different groups. The top two - "Normal" and "Dissolve", make up the first group. Below them, "Darken", "Multiply", "Color Burn", and "Linear Burn" make up the second group, and so on. There's six groups in total, and you may get the impression that the reason certain blend modes are grouped in with other blend modes is because they have something in common, and you'd be correct!
Well, you'd be correct except for the first group at the top. The "Normal" and "Dissolve" blend modes have absolutely nothing to do with each other, even though Adobe chose to group them together. You could easily go your whole life never using the "Dissolve" mode, since it's pretty much useless, especially when it comes to photo editing, whereas "Normal" is the default blend mode that all layers are automatically set to unless you change it. So the first group at the top isn't really a group at all, unless you want to think of it as the "We Have Nothing To Do With Each Other" group. The rest of the blend modes, though, are grouped together because they most definitely have something in common with each other. Here's a breakdown of the various groups:
As we can see in the CCFC (Color Coded For Convenience - yes, I just made that up) diagram above, the "Darken", "Multiply", "Color Burn", and "Linear Burn" blend modes are the Darken modes. Why? Because each one of them has the effect of making the image darker. Notice that the Multiply blend mode is included in the Darken group. If you remember, it's one of the five blend modes you absolutely need to know and one of the modes we'll be taking a closer look at in a moment.
Next, the "Lighten", "Screen", "Color Dodge", and "Linear Dodge" modes make up the Lighten group. Each one of them has the effect of lightening the image. Notice that the Screen blend mode is included in the Lighten group, another one you need to know and one of the ones we'll be looking at.
Below that, the "Overlay", "Soft Light", "Hard Light", "Vivid Light", "Linear Light", "Pin Light", and "Hard Mix" modes make up the Contrast group. Each one both darkens and lightens the image, boosting contrast. Notice that the Overlay mode, another one you need to know and one we'll be looking at, is part of the Contrast group.
Next up is a group we're not going to be looking at in this discussion, the Comparative group, made up of the "Difference" and "Exclusion" blend modes. Both of these modes are for comparing pixels between layers and neither one of them is used very often, especially in photo editing. Very rarely would you have a use for the "Difference" mode, and you'll use "Exclusion" almost as much as you use "Dissolve", which is to say pretty much never.
Finally, we have the Composite group, also known as the HSL group, which stands for "Hue, Saturation and Luminosity", which just happen to be the names of three of the four blend modes included in this final group, along with the "Color" mode. The blend modes in this group all have something to do with either the color or luminosity (lightness) values in the layer, and the Color and Luminosity modes make up the last of the five essential blend modes you need to know when it comes to editing photos and images in Photoshop.
So far, we've seen that even though the number of layer blend mode choices we're given in Photoshop can seem a bit overwhelming, there's really only five main types of blend modes. There's ones that darken the image, ones that lighten the image, ones that both lighten and darken at the same time to boost contrast, ones that compare pixels between different layers, and finally, ones that affect either the color or luminosity values of an image. Already, we've managed to take up to 25 seemingly different blend modes and break them down into only five main types (which the exception of "Normal" and "Dissolve", which we're not going to concern ourselves with). Not bad for starters, but we can break things down even further than that because out of those five main types, there's really only five blend modes you need to know when it comes to photo editing - one from the Darken group, one from the Lighten group, one from the Contrast group, and two from the Composite group.
The first one we need to look at is Multiply, and as we saw in the diagram above, it's found in the Darken group, so right away, we know it has something to do with darkening an image. In fact, it's the only blend mode from the Darken group you really need to know, and it also happens to be the most widely used blend mode of all. We'll look more closely at the Multiply blend mode next.
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