When you’re first learning about image editing, the sheer amount of knowledge and jargon there is to learn can seem a bit intimidating, but it doesn’t have to be.
Layer modes in GIMP are a perfect example because they seem complex and mysterious at first, but they’re actually fairly simple to use.
The real trick lies in figuring out when it’s actually beneficial to use them!
- Layer mode determines the way a layer will affect the layers below it in the layer stack during the compositing process.
- Layer modes are also known as blending modes.
- There are 38 different layer modes in GIMP.
- Most layer modes are highly technical and not in common usage.
- Layer modes can be changed in the Layers panel.
The Basics of Layers
Before we go any further, it’s a good idea to make sure that we’re all on the same page about how layers work in GIMP. If you’re already familiar with image layers, feel free to jump ahead to the next section.
The classic example that is used to explain the layers concept is to imagine a stack of perfectly transparent plastic sheets. Each sheet can have something different drawn on it, but when you view the stack from above, you see a single image that is created by combining each of the sheets together.
The simplest practical example is a copyright watermark on a photo. The photo is on one layer, and the copyright watermark text is on a second layer, which is placed on top of the photo layer.
You can move the copyright watermark around to position it anywhere you want overtop of the photo, and when you view the image in the main document, the two layers get visually merged into a single combined output.
Layers in GIMP are organized into a “layer stack” just like in the transparent plastic sheets example, which is visible in the Layers panel at the bottom right corner of the interface.
If you were to place the copyright watermark text layer beneath your photo layer, you wouldn’t be able to see it at all because it would be covered up by the photo.
You can have as many layers in your GIMP document as your computer can handle – although adding too many layers into a document can make the fastest computers struggle to keep up!
Layer Modes in GIMP
By default, all layers in GIMP use the Normal layer mode. Normal mode has no impact on layer contents or compositing, so when your separate layers are combined into the image that displays in the main document window, they are simply stacked up together with no alterations.
When you change the layer mode in GIMP, you change how that layer affects the layers below it in the layer stack. Each layer mode has a different effect, and some of them will only be noticeable if the layer contains a certain pixel color or pixel value.
GIMP has 38 different layer modes, and most of them are very technical and have limited practical use. There are some that you’ll probably never need to use. In fact, there are so many that even GIMP’s developers didn’t bother finishing the explanation of each one in the user manual, and the relevant section just says TO DO (as shown below).
I’m also not going to explain every single one of the layer modes since there isn’t enough space in this article, but if you’re curious about the explanation and mathematics behind some of them, you can check out the Layer Modes section of the user manual.
Fair warning, though: unless you find mathematical formulae to be enlightening, you’re probably better off just playing around with the different layer modes until you find something that’s useful – but more often, you won’t find one.
That being said, there are a few useful layer modes that can be a big help when working on photo composites and other digital art projects: the Screen layer mode, the Multiply layer mode, and the Overlay layer mode are useful for creating partially transparent overlays.
If you want to experiment a bit further afield, create a new layer and apply a colored gradient that fades into transparency, then use that layer to experiment with different blending modes.
You can also vary the hue and brightness of the gradient layer to see the full range of possible layer mode compositing effects, although there’s usually a better way of creating a similar result. It all depends on the effect you want to create!
How to Change Layer Modes
Luckily for all of us, changing layer modes is a much simpler task than understanding exactly what each layer mode does.
To change layer mode in GIMP, select the layer you want to change in the Layers panel, then open the Mode dropdown menu and select your desired layer mode from the list.
That’s all there is to it! You can change layer modes as often as you like since layer modes are an example of non-destructive editing. No pixels are permanently altered by changing layer mode, so feel free to experiment with the available options. You can always change the layer mode to Normal to get things back to (you guessed it!) normal.
A Final Word
Hopefully, the word “layer” hasn’t lost all meaning by the end of this article! You now know the basics of layer modes in GIMP, as well as how to change the layer mode to get your desired results.
While you probably won’t ever have a use for most of the available layer modes, the few that are useful are a big help when making photo composites and other digital art projects.
Happy layering!About Thomas Boldt