How to Use Layers in GIMP

Learning how to use layers in GIMP is crucial for achieving the creative vision you have for your images. In this article, you’ll learn everything about GIMP layers to get the look you want. 

As well, you’ll get answers to the seven most common questions beginners ask about GIMP layers.

Here is what you’re going to learn:

1. How to create a new layer and add attributes.
2. Discover what the “Layer Boundary” is and how to adjust it.
3. How to group layers to get organized.
4. How to use Layer Masks for precise editing.
5. How to rotate a layer for straightening horizons.
6. How to link multiple layers.
7. How to align a layer in the middle of your canvas.

If you’re new to GIMP, I recommend you start with my first article on GIMP editing basics.

The GIMP Layer Panel

Before showing you how to work with layers in GIMP, first, let’s go over the Layers Panel. If it’s not visible, go up to the menu under Windows > Dockable Dialogs > Layers to open the panel.

The Layers Panel consists of three main sections (as shown above):

1. Top: Here, you’ll find three options for interacting with your layers; Modes, Opacity, and Locks.
2. Middle: This section will reveal the layers in your document.
3. Bottom: From here, you’ll find eight different icons to help you work with and manage your layers.

Layer Modes

At the very top is an option (pull-down menu) called Mode. This is a method of altering how your layers interact with one another.

These are similar to Blend Modes in Photoshop. When you choose from the drop-down menu, the active layer will “blend” with the layer below according to the mode you have chosen.

Opacity

To adjust the transparency of a layer, use the Opacity slider to increase or decrease as needed. 

Lock

To prevent accidental adjustments to a layer, you can lock it. There are three choices available here.

The first the paintbrush icon) prevents any kind of edit being done to the layer. The second (arrows icon) prevents the contents of the layer from being moved. The third lock (checkerboard icon) prevents adjustments to the transparency of the layer.

Layer Previews

Each new layer you create will display a preview (thumbnail) of the layer contents in the middle of the layer panel. The size of the layer previews displayed can be adjusted larger or smaller to suit your preferences. 

Just follow these directions:

• Navigate to the top right of the Layer Panel and click on the left-pointing arrow (indicated below in the red box).
• Scroll down to Preview Size and choose your preferred size (see red arrow).

Manage Layers

You’ll find the following options for managing your layers in GIMP, at the bottom of the layer panel as shown below.

1. Create a new layer by clicking the first icon (1).  
2. The second option is used for creating a grouped layer (2).
3. The next two choices allow you to change the stacking order of a layer either up or down, one position at a time per click (3).
4. Next, this option will duplicate your active layer (4).
5. If needed, you can merge an active layer with the one below it by clicking on this icon (5).
6. The funny-looking clown icon is used for creating a Layer Mask (6).
7. If you no longer require a specific layer clicking the “x” icon will delete it (7).

Create a New Layer

As mentioned previously, to create a new layer just click the first icon at the bottom of the layer panel (#1 in the image above). 

Before finalizing the layer’s creation, you may want to make some choices in the “New Layer” dialog window that pops up. 

Here are the options and a description of each. 

• Layer Name: This allows you to add a name for your layer that describes its purpose. For example, if the layer’s intended use is for retouching, name it “Retouch”. This is helpful for identifying them easily if you have many layers. 
• Color Tag: Adding a color overlay to your layer preview can help you organize them by type. For example, blue could represent retouched layers, green might be for special effects, etc.
• Mode: Allows you to select the type of blending mode applied to this layer.
• Blend Space: This option and the next two are advanced settings. The defaults are perfect in most situations.
• Opacity: Sets the transparency level of your layer.
• Width + Height: Sets the dimensions of the new layer if you’d like it to be different from the current canvas size.
• Offset X + Y: You can position the layer’s contents to be in a specific location within your canvas by adjusting these settings.
• Fill With: There are five choices for filling your new layer with either a solid color, transparency, or a pattern.
• Switches: Set the layer management options as needed.

All of these options, with the exception of Fill With and the size (width/height), can be changed at any time by right-clicking on a layer and choosing “Edit Layer Attributes.”

What’s the yellow dotted line?

A unique characteristic in GIMP is the yellow dashed line around a layer. This yellow line is known as a “Layer Boundary”. 

At first, it’s not that big of a deal. It’s not until you resize a layer larger or smaller than the canvas that it can become annoying.

So if you want to turn it off, go up to the top menu and select View > Show Layer Boundary to show or hide it.

Organize your layers in groups

As you work on an image, you’ll begin creating numerous layers to achieve your desired final result. The greater the number of layers you make, the more chaotic it will be and the slower workflow. 

The solution is to put similar types of layers together into a group.

First, to create a new grouped layer, click the second icon at the bottom of the layer panel. Double click the “Layer Group” name and title it accordingly.

To add layers inside the group, just drag and drop them into it. Click on a layer, hold your mouse button down, and drag it over the layer group. Once you see an outline around it, release your mouse button to drop it, and the layer will be added to the group. 

Repeat this for every layer you’d like to add to that group.

Layer Masks

Utilizing layer masks is an essential skill that will elevate your editing!

A mask gives you precise control of where an edit is applied in your image. So, take the time to learn how to use layer masks.

For example, suppose you have a portrait where the skin tones are unnatural. In that case, you could lower the Saturation with the Hue/Saturation tool, as shown below.

However, that will adjust the Saturation for the entire image. If you want to only apply it to your subject’s skin (and hair in this case), you’ll need to use a Layer Mask. 

Follow these steps: 

• First, duplicate the image layer and give it a new name. To rename it, double-click the existing name and type in a new one.
• Make your saturation adjustment with the Hue/Saturation tool; Colors > Hue-Saturation. After making the edit, click the OK button.
• Add a Layer Mask by clicking on the “clown” icon and choose “Black” for the color. After clicking the “Add” button, the edit will disappear!
• To fix the skin, grab your Paintbrush tool (B) and set the foreground color swatch to white. Paint over the skin, and the edit will be applied!

It’s important to note here that whatever shows as white on the mask – that part of the layer will be visible or show. Whatever is black on the mask will be hidden. Think of it as actually looking through a Halloween mask with the eyes cut out. 

If you paint at a lower opacity (gray tones) that means it will partially show those sections of that layer. 

NOTE: Make sure you are painting on the mask and not the layer. The red arrow above indicates the mask. Notice the white outline around it. If the image thumbnail is outlined instead, click the mask to make it active and your painting will apply there.

Rotating GIMP layers to straighten an image

Sometimes, getting the horizon (or vertical lines) straight in-camera can be challenging. But not to worry, this is easily corrected in GIMP.

To fix this problem, you can rotate the layer as follows: 

1. First, set a guide line along the horizon to assist you when rotating. Click on the top ruler and drag it down to add a guide along the horizon (blue dotted line seen in the image below).
2. Grab the Rotate Tool (Shift + R keyboard shortcut) and click on the image to activate the tool.
3. In the Tool Options (Windows > Dockable Dialogs > Tool Options), choose “Crop to Result” under the Clipping drop-down menu.
4. Adjust the image angle as needed and hit the Rotate button when you’re happy with the adjustment.

How to Link Layers in GIMP 

There may come a time when you’ll need to move, rotate, or resize multiple layers simultaneously and equally. Unfortunately, with the current version of GIMP, it’s not possible to select multiple layers at one time.  

In order to get around this, you can link two or more layers together and adjust them as you see fit. 

To mark a layer as linked, click to the left of the layer thumbnail preview (right of the eye icon) to add a link (see the red box in the image above for the precise location). 

Do this for each layer that you want to be part of the link.

NOTE: Being able to select multiple layers is coming in GIMP 3!

Aligning Layers

Knowing how to align layers is another frequently asked question for new GIMP users. 

Although you may have already found the Alignment tool, there are no built-in instructions on how to use it. This will likely lead to frustration because you don’t know the secret step. 

But all will be revealed below! 

How to align layers in GIMP

The secret for aligning layers in GIMP, is to activate the ones you want to be aligned via the canvas and not the layer panel. This is due to not being able to select multiple layers in the current GIMP version.

First, grab the Alignment Tool by hitting the Q as a keyboard shortcut. To activate a layer to be aligned, click on its contents inside the canvas. You’ll know the layer is activated when you see a small square in each corner of that layer’s content (see below).

Then, in the Tool Options, make sure the “Relative to” is set to “First Item.” Below that drop-down menu, click on the icons to align the layer accordingly to your canvas. 

To align two or more layers with each other, you’ll need to activate the additional layers to be aligned. As before, activate a layer with the Alignment tool. Then, hold down your Shift key and click on each additional layer. 

This has the effect of selecting multiple layers. You can now use the alignment options in the Tool Options to align your layers.

Conclusion

These seven tips should give you a good base for getting starting editing with GIMP. 

Now that you’re on your way to mastering layers in GIMP let me know if you have any questions in the comment area below.