Mirroring an image is one of the most common techniques in image editing, whether you’re creating a reflection or a shadow for a photo composite or if you just want to flip a landscape upside down for fun.
It’s such a common task that there are several ways to mirror an image in GIMP, so let’s take a quick look at how it works.
Quick Navigation
The Flip Transformation
Depending on the image editor you’re using, mirroring can have many different names, but the mirror/reflect tool in GIMP is called the Flip tool.
The quickest way to activate it is to use the keyboard shortcut Shift + F, but you can also find it in the Toolbox nested in with the rest of the Transform tools. Right-click the Transform tools icon and select Flip from the popup menu, as shown below.
If you prefer to go the long way, you can open the Tools menu, select the Transform Tools submenu, and click Flip, but that seems like a lot of unnecessary extra effort unless you’re unable or unwilling to use the other methods.
When the Flip tool is active, the mouse cursor will change to indicate the current mirroring direction. By default, it is set to horizontal mirroring, but you can switch it to vertical mirroring by holding down the Ctrl key. Notice the arrows in the cursor change direction to match!
If you want vertical mirroring to stay as the default option, you can go to the Tool Options panel and change the Direction setting to Vertical. In this mode, holding down the Ctrl key will still swap the tool into the alternate direction.
Once the Flip tool is configured the way you want, simply click once anywhere on your image, and it will flip in the chosen direction!
How Do I Mirror a Layer in GIMP?
Mirroring an individual layer is actually the default setting for the Flip tool, but when you’re working with a single-layer image, this doesn’t matter. Sometimes the default setting may be different.
For example, if you accidentally misconfigured the tool in the past and GIMP “helpfully” remembered your previous settings.
The Flip tool has four different transform modes: Layer, Selection, Path, and Image. The modes are fairly self-explanatory, so there’s no need to go into a long-winded explanation, but you may need to swap the settings between Layer and Image, depending on the structure of your document.
To change transform modes, simply click the appropriate icon in the Tool Options panel. Layer mode is on the left, and Image mode is on the right.
Quick Project: Seeing Double
Here’s a quick project you can do to experiment with the mirroring effect a little bit. It might be useful if you’re making a double-sided printout or if you just want to experiment with your imagery a little bit and have some fun with symmetry.
To try this for yourself, load an image you want to mirror in GIMP, and then open the Image menu and click Canvas Size.
In the Set Image Canvas Size dialog window, click the chain link icon between the Width and Height fields to unlink the aspect ratio.
If you want to double up your image horizontally, increase the Width setting to double the original size. If you want to double your image vertically, increase the Height setting to double the original size.
Tip: Unless you like doing quick math, you can change the unit setting to percentage and then enter 200 in the Width field to double the width of your canvas.
Click the Resize button to adjust the canvas size.
Next, duplicate your original image layer so that you have a second copy of the image. You can use the keyboard shortcut Ctrl + Shift + D (use Command + Shift + D if you’re using GIMP on a Mac), or you can right-click on the layer in the Layers panel and choose Duplicate Layer from the popup menu.
You can also open the Layers menu and select Duplicate Layer.
The newly duplicated layer should be automatically selected in the Layers panel, so it’s time to start flipping!
Switch to the Flip tool using the keyboard shortcut Shift + F, or find it in the Toolbox. Double-check that the Flip tool is set to mirror in the same direction you expanded your canvas, and click anywhere on your image to mirror the new layer.
“Of course, you always have the best ideas!”
Last but not least, switch to the Move tool using the keyboard shortcut M or by clicking the Move icon in the Toolbox, and reposition your layers so that you get the desired mirroring effect. Make sure you view the image at 100% zoom level when aligning the images!
You can also hold down the Ctrl key when using the Move tool to constrain the movement to a straight line.
A Final Word
That covers everything you need to know to mirror an image in GIMP! I strongly encourage you to take the time to learn the keyboard shortcut for the Flip tool since you’re probably going to be using it a lot if you do any kind of digital artwork in GIMP.
It might not seem like much of a speed boost at first, but once you get used to using keyboard shortcuts for everything, you’ll wonder how you ever got anything done without them.
Happy mirroring!
About Thomas Boldt