GIMP Layers 101 {the Complete Guide}

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Layers in GIMP are essential for everything you do in, well, GIMP. Here are a few examples of how you’ll use them…

Editing images (non-destructively) requires multiple layers
Adding text auto-creates a new layer
You'll need to add a new layer for creating shapes
Applying gradients requires a new layer
Advanced image editing requires a Layer Mask

In this guide, you’ll learn everything you need to know about layers. This includes understanding what they are, the four types of layers you’ll encounter, the four ways to customize them, layer attributes, and more.

This article is the first in a series of articles on layers. Other Layer tutorials will go in-depth for particular types of layers and how to use them in the real world.

First, we need to set the foundation of layers before moving onto more advanced layer concepts.

So, if you’re ready… let’s do it!

What Is a Layer?

A layer in editing software like GIMP and Photoshop is no different than how artists work in the real world. A canvas or a piece of paper is in and of itself a layer. It’s the media by which you paint or draw on. A photographic piece of paper is a layer too.

The power of a layer is in the ability to, well, Layer (or stack) them. If you have a photographic print and decide you’d like to add text (after it’s printed), you could print it out on clear acetate. Then, you could place it over the image. The clear acetate is the second Layer in your artwork.

When you open an image in GIMP it’s the first Layer for your project. When you add text with the Text Tool, a new layer is created with its content.

Four Types of GIMP Layers

When working with GIMP layers, you’ll use four main types of them. Each is distinguishable from the others based on the thumbnail preview of that Layer.

Here are the four kinds of GIMP layers…

BACKGROUND LAYER

The thumbnail preview of this type of Layer shows the image in its entirety. Background layers work a little differently in GIMP vs. Photoshop for those transitioning from Photoshop.

In Photoshop, when you open an image, the Layer is named “Background” and is locked from being manipulated. You have to unlock it to make adjustments to that Layer.

In GIMP, the Background is not locked, and you can begin working on it immediately.

GROUPED LAYER

The preview of a Grouped Layer looks like a folder. To group layers, choose this option from the bottom of the panel. Once you place your layers inside, you can collapse them to hide those contained within.

For some image edits, I can use anywhere from 20 – 50 different layers! Some artists use more.

Having many of them creates chaos, slows down your workflow, and can be detrimental to your final artwork. I recommend getting organized by grouping similar types of editing layers together.

Plus, unlike Photoshop, you can not select more than one Layer at a time. Instead, use a Grouped Layer to achieve this.

PIXEL LAYER

A Pixel-based layer will show the pixels being used in the thumbnail preview. The entire thumbnail will be filled with pixels like an image. Or only a part of it based on how many pixels make up that Layer. If only a portion, then the rest of the preview will have a transparent background (made up of different colored squares).

Every Layer you create requires pixels to form your image or designs. Even a text layer is pixel-based. I make this distinction for those coming from Photoshop. Text and shapes in Photoshop are vector-based.

Vectors allow elements in a layer to be resized without a loss of quality. If you create a shape layer and resize it larger, it will become pixelated. This may change with the release of GIMP 3.0+ since shapes are on the roadmap for implementation.

TYPE LAYER

When adding text, you’ll end up with a Text Layer. It’s distinguishable from the other types with its “A” icon in the thumbnail. If you deactivate the Text Tool and decide to add more text, you can create a new Text Layer or add to an existing Text Layer.

Four Ways To Customize Your GIMP Layers

The following includes the four main ways you can customize a layer.

Layer Mask - offers precise image editing.
Opacity - increase or decrease the visibility of the pixels of the Layer.
Blending or Layer Modes - the ability to blend two together.
Layer Effects - includes things like adding a stroke to a graphic (or text) or a drop-shadow.

LAYER MASK

A Layer Mask gives you the precision to apply an edit in a specific location of an image.

OPACITY

Setting the Opacity slider of a layer allows you to decrease the visibility of that Layer. You can also use it to tone down an edit applied to an image layer.

BLENDING MODES

Blending Modes provide a multitude of creative tools for helping you achieve your creative vision. Not all Modes are created equal and will not work with every type of Layer. It depends on the intended purpose of what the Mode was designed to do.

Discover an in-depth view of each of the 38 Blending Modes, how they work, how to use them, and more by clicking here.

LAYER EFFECTS

Layer Effects were designed to be used with graphics. They can be used with a text layer or with shapes. Unlike Photoshop, there are very few effects to choose from.

Although you can extend the library effects with plugins provided by third-party developers. The only problem you may run into is when a developer disappears and doesn’t update the plugin. This recently happened to a plugin I promoted through my 37 GIMP Graphic Design class.

An expansion of the type of Layer Effects is in the roadmap for 3.0+. Hopefully, the sooner, the better.

GIMP Layer Stacking Order

Top of the world… Photo by Marius.

Stacked! Photo by Suzy.

In the world of layers, the one on top is dominant. Or at least can hide the layers below and other special powers.

As you now know, layers are made up of pixels. If the entire layer is filled with pixels, is above all other layers, then no other layers can be seen. Only when a portion of the pixels from the top layer is removed or hidden (Layer Mask) will you be able to see the layers below.

Although you could also lower the Opacity of the top layer to reveal the others too. Lower level layers will also become visible if the topmost layer is smaller than the canvas’s dimensions. So much for being dominant.

The stacking order also has consequences on how layers interact with each other. For example, when you apply a Mode to a layer, it blends in with the one below.

In the layer management section (coming up soon), I’ll show you how to rearrange your layers.

The Layer Panel

How To Access the Layer Panel In GIMP

As with other tools, layers can be accessed via a panel called “Layers.”

The Layer Panel lists each Layer created and provides additional tools for using your layers. Plus, there are four places (1 hidden) for different tools for working with them.

To view the Layer Panel in GIMP, go to;

Windows > Dockable Dialogs > Layers.

Top Layer Panel Section: Includes a drop-down menu labeled "Mode" and an option for adjusting a layer's opacity. The Mode is also known as Blending Modes or Layer Modes. Also, options for locking the layers can be found here too.
Middle of Layer Panel Section: Includes a list of all the current layers.
Bottom Layer Panel Section: At the bottom, you'll find icons with different tools for working with your Layer (s).
Top Right of Layer Panel: To the right of the Layer Panel, you'll find a left-pointing icon. This offers multiple layer properties for customizing how the panel looks.
Hidden: If you right-click on a layer, you'll be presented with a pop-up menu with more tools for working with them!
Layer Preview: shows the contents of the Layer and updates as you edit.
Layer Mask:- shows how you adjusted the visibility of the Layer. The scope of a Layer Mask is beyond this guide. I've created a separate in-depth guide on Layer Masks to share everything you need to know about them.

The Layer Tools

Let’s explore each of the tools at the bottom of the Layer Panel. From left to right, we have the following…

New Layer - allows you to create a new layer and adds it to the Layer Panel.
Layer Group - enables you to create a layer for organizing your layers.
Arrows - up and down arrows allow you to rearrange the order of your layers.
Duplicate Layer - creates a duplicate layer of the active Layer.
Merge - merges the active Layer with the one below.
Layer Mask - an advanced photo editing technique that allows precise control of where an edit is applied.
Delete Layer - use this to delete a layer.

NEW LAYER

It’s essential to create a new layer for achieving your creative vision for the project you’re working on. For example, suppose you wanted to create a gradient background or overlay. In that case, a new layer will keep it separate from the rest of your artwork.

ARROWS

Stacking your layers is vital for achieving your creative vision. For example, if an image layer is above a text layer, the text will not be visible! Use the arrows to rearrange the layer order. Or click on the Layer and drag it into a new position.

DUPLICATE LAYER

Duplicating a layer is vital for editing an image non-destructively. If you edit the original Layer, save the image, and realize you made a mistake, you can not go back to the original!

MERGE

Sometimes it’s not necessary to have a specific layer separate from others. In this case, if you’re confident you won’t need the original Layer, it can be merged with the one below. Remember, if you change your mind, it’s too late after merging.

LAYER MASK

Gives you control over where the edit (s) are applied on that image layer.

ANCHOR LAYER

This tool is not visible in the Layer Panel until you copy/paste a selection. This will create what is known as a Floating Selection. To add the selection as a new layer, hit the Anchor Layer icon (replaces the Merge icon temporarily).

Managing GIMP Layers Via the Layer Panel

In addition to the Layer Panel sections covered so far, you may have noticed some other data within the panel too.

This includes a section called “Lock” and two icons to the left of the Layer. Let’s look at those next.

LOCK

The Lock gives you three options for locking a layer. This includes;

You can activate one, two, or all three at once on a specific layer.

ICONS

Eye - The first icon, to the left of a layer, looks like an eye. This, by default, is set to show the Layer. If you click on the icon, it will hide the Layer. Click in that area again to reveal it.
Layer Link - Click to the eye icon's right, on 2 or more layers, to add the chain link icon. Any linked layers will allow you to reposition them on the canvas simultaneously.

Hidden Layer Editing Tools

Right-clicking on a layer will reveal a pop-up window with more options for working with that Layer.

You’ll find some tools that are available directly from the Layer Panel. However, there are new ones not available elsewhere.

Edit Layer Attributes: This gives you access to the Layer Attribute window. It's the same window that pops up when creating a new layer.
New From Visible: Merges all existing layers into one new Layer and keeps the originals intact.
Layer Boundary Size: The dimensions of a layer is it's "boundary" size. Any image edits are confined to that boundary. When adding Layer Effects, part of it may not be visible if they're exceeding the Layer Boundary. Use this to increase or decrease the perimeter of the Layer.
Layer to Image Size: This option resizes the Layer Boundary to match that of your document.
Scale Layer: Gives you the option to resize only the active Layer.
Layer Mask: Options for managing the Layer Mask.
Add Alpha Channel: An advanced tool for making a layer capable of handling transparency even though it's not.
Remove Alpha Channel: Removes the Alpha Channel applied to it.
Alpha to Selection: Confines the Alpha Channel to a selection and not the entire boundary of a layer. This is used repeatedly throughout the 20+ text effects tutorials I have for.
Merge Visible Layers: A destructive action that merges all visible layers into a single layer. Not recommended.
Flatten Image: Another destructive action that merges all visible and nonvisible layers. Again, not recommended.

Layer Attributes

When you create a new layer, you’re presented with a new layer dialog window with options for organizing the Layer.

You can manage the layer attributes of an existing layer, too. To do so, right-click on a layer and choose “Edit Layer Attributes.”

Layer Name: give the Layer a name of your choosing.
Color Tag: organize a layer with a color label.
Mode: set the Blending Mode of the layer
Two Spaces and a Composite Mode: these are advanced settings that are set to Auto by default.
Width + Height: set the dimensions of the Layer if it should be different from the canvas.
Offset X + Y: reposition the new Layer if it should be offset on the canvas.
Fill with: This gives you the option to add a transparent layer, one with a solid color or pattern.