Layers are one of the most useful features of digital image editing, whether you’re working on a new social media graphic or a photorealistic art piece. GIMP’s layer system could use a bit of work, but that makes it all the more important to know how to merge layers in GIMP.
Because GIMP won’t let you select or edit multiple layers at once, merging your layers allows you to quickly apply consistent effects to multiple image elements at the same time as well as a number of other useful transform effects without relying on tedious layer linking structures.
To merge your currently selected layer with the one below it, there’s only a single step to follow, but three different ways you can accomplish it.
Method 1: The Layers Panel Method
In the Layers panel, click the Merge down button.
Your currently selected layer will be combined with the layer below it in the layer stack, and that’s all there is to merging layers in GIMP!
Method 2: The Direct Layer Method
This method can be as fast as the button method above, but the comically huge menu that appears has so many options that it can slow you down.
To open it, just right-click on the appropriate layer in the Layers panel stack and click Merge Down.
Method 3: The Layer Menu Method
Of course, if you prefer to work with the menus, you can achieve the same result by opening the Layer menu and selecting Merge Down.
If you want to learn more about different merging options, read on!
Advanced Layer Merges
It’s probably a bit silly to call this ‘advanced’, but let’s run with it. The quick methods that I explained above work great for an image with only two or three layers, but you might find yourself with twenty, thirty, or a hundred layers, depending on the project.
No matter how many layers you have, you can merge them all at once by holding down the Ctrl button while you click the Merge Down button in the Layers panel.
You can also open the Image menu and choose Merge Visible Layers, or use the keyboard shortcut Ctrl + M (Command + M for Mac users).
Whichever route you choose, GIMP will display the Merge Layers dialog box so that you can decide the size of the final result.
In order to make sense of this dialog, it helps to remember that GIMP treats the size of each layer as independent from the overall size of your image. Layers can be smaller, but they can also extend beyond the edges of your visible image workspace.
For most situations, the Clipped to image setting is the best option. This will trim all your layers to match the dimensions of your image and discard anything that extends beyond those borders. If you want to retain all that image data because you’re planning to change your canvas size later, choose Expanded as necessary.
If you’re wondering about layer groups, you might have noticed in the screenshots above that GIMP doesn’t list any options for them, except in the Merge Layers dialog box. This is a bit of an odd UI quirk for GIMP, but the options appear only if you’ve actually created a layer group.
That makes sense for the contextual menu, but I’m not sure why GIMP felt it was a good idea to alter the main Layer menu contents. However, you can open the Layer menu and select Merge Layer Group once you’ve created one.
Merge, Don’t Flatten
If you want to combine all your layers, you could also open the Image menu and choose Flatten Image, which does technically merge all your layers. However, it also has the unfortunate downside of discarding the alpha channel in your image and replacing any transparent pixels with your current background color – so I don’t recommend it as a method.
That’s just about everything there is to know about how to merge layers in GIMP! If you want to learn more about working with layers, I’ve got a bunch of guides around the TGT site for you to dig into, although keep in mind that GIMP’s layer system is a bit rudimentary right now.
The next version of GIMP should include a rework of some of the layer functionality, so hopefully, we’ll get a bit more flexibility out of them once the development version finally gets the stamp of approval and is released to the public!About Thomas Boldt