Advanced editing projects usually involve working with layers, since they’re the best way to keep your image elements separate and organized. GIMP’s layer system is extremely confusing at the moment, so don’t feel bad if you’re getting frustrated with how it works – or rather, doesn’t work.
Many Photoshop users expect GIMP to handle layers in a similar way (including me, when I first started using it), but GIMP has other ideas: it actually doesn’t let you select multiple layers.
Wait, what? Yes, you read that right, unfortunately.
Even though you can’t select multiple layers at once, you can apply transforms to multiple layers. Transform operations change the size, rotation, and position of your image objects, but GIMP doesn’t allow you to apply other edits like contrast adjustment or filters to multiple layers at once.
As I said earlier, the layer system in GIMP is a bit of a mess at the moment. But there are a couple of tips and tricks I can pass on to help you make the most out of the GIMP layer system, and hopefully speed up your workflow at the same time.
Layer Linking in GIMP
If you want to apply a transform operation on multiple layers in GIMP – scale, rotate, or move – then the fastest way is to link your layers in the Layers palette. Layer linking does exactly what it says on the tin: any transform adjustments you make are applied to all linked layers at the same time.
By default, the Layers palette is located in the bottom right corner of the GIMP workspace, unless you’ve done some additional layout customization.
Linking your layers is extremely simple, although it’s not immediately obvious how it works just from looking at the Layers palette. Beside each layer, there’s a small eye icon to indicate if the layer is visible, but there’s also a small gap – click in that gap, and a wild chain-link icon appears!
You can also link layers by double-clicking the layer thumbnail to bring up the Layer Attributes window, and then selecting Linked on the side, but it’s not nearly as fast as the shortcut using the Layers palette.
Using Layer Groups in GIMP
Layer grouping is a useful organizational tool that helps to smooth over some of the gaps in GIMP’s layer system by offering a tiny bit more flexibility. Once you place your layers into layer groups, you can move multiple layers (within the group) around the Layers palette and link groups like single layers.
Creating a layer group is a simple process. At the bottom of the Layers palette are a few quick shortcut icons – we want the “new folder” icon located second from the left, Create a new layer group and add it to the image.
Layer groups are really just an organizational tool that allows you to maintain different sets of linked layers at the same time since grouped layers behave the same way linked layers do. Transform operations applied to groups apply to all the layers within.
But it’s not exactly the best solution, because linked layers don’t have to be next to each other in the layer hierarchy, but layers within groups must also move through the hierarchy together.
This can make for some headaches when creating complex composites, but it’s all we have to work with until the next version of GIMP is released.
Bonus Tip: A Scripted Semi-Solution
The only other workaround that I’ve discovered involves a type of script that won’t work for all situations. The script copies each of your layers into a new document and arranges them side by side on one layer, and then you can apply any edits you want – filters, color adjustments, etc.
Once you’re done, the script splits that one composite layer back into all your original layers. The end result is that you’ve edited multiple layers, but before I even tested it out, I could already see that it wouldn’t work in a lot of different situations.
Many filters and edits use surrounding content to define their effects, so you might get unwanted effects from one neighboring layer-frame that wouldn’t actually be nearby in the properly multi-layered version of the image, creating unexpected results (though that can be fun too).
If you want to give it a shot, there are a few different versions of this floating around, but the one I discovered is named “ofn-layer-tools” and is hosted on SourceForge along with a few other scripts written by the same author. Take a look through the list for more unexpected goodies!
They have been tested and are working with the latest version of GIMP, but that may change as new versions are released. Naturally, I can’t promise that it will work for you, but it might be worth a try if you’ve got a lot of layers to work on.
Ah, the joys of free software 😉