In this tutorial, I’ll be demonstrating the easy process for scaling a selection in GIMP. I’ll be using GIMP 2.10.18 for this tutorial, which is the latest version of GIMP at the time of this article.
Step 1: Draw Your Selection
There are a variety of ways to draw a selection in GIMP. You can use the Rectangle Select tool, Ellipse Select tool, Free Select tool, Foreground Select tool, Scissors, Fuzzy Select, Select by Color, Paths tool, or even a Quick Mask or Layer Mask to Selection. I won’t go into detail as to how to draw a selection for this tutorial – though you can check out my GIMP Selection Areas Basics and GIMP Selection Areas Advanced tutorials on YouTube for more on that subject.
Step 2: Grab Your Scale Tool and Change the Mode
Once you have your selection area drawn, as I do in the image above (red arrow), you can grab the scale tool from your toolbox (tools are grouped together as of GIMP 2.10.18, so you can find your scale tool in the Transformation group denoted by the yellow arrow in the image above – you can also use the shortcut key “shift+s” to grab the scale tool). I’ll click on the “Scale” option from the tool group to activate my scale tool (green arrow).
Once your scale tool is active, navigate over to your Tool Options panel (this panel is usually underneath the Toolbox by default – though I’ve customized my GIMP workspace to have it on the right side of my image window – outlined in green in the image above).
In the Tool Options for the scale tool, you’ll see an area labeled “Transform:” with a series of transform options (outlined in blue in the image above). This is where you can change the mode of the transformation you are applying with the scale tool. By default, the scale tool is set to transform your layer. However, the second option is a red box with a dotted line around it (green arrow). Clicking this icon will change the mode of your scale so that it will now transform a selection.
Step 3: Click on the Selection You Wish to Scale
Now that our scale tool is in the “Selection” transform mode, we can simply click on the selection area we’d like to scale. Clicking on the selection area with the scale tool will bring up the “Scale” dialogue box (red arrow in the image above), as well as place a rectangle around the selection area containing transform handles (these are the boxes located in the corners and midpoints of the rectangle – green arrows in the above image).
For starters, make sure your chain-link icon is locked (red arrow in the image above) so that the selection area will maintain its original aspect ratio while you scale it up or down (this just ensures you don’t end up with a squished or stretched out selection area).
If you’d like to scale the selection area up (make it larger), click and drag any transform handle (red arrow in the image above) outward and hold the ctrl key (this will scale the selection area from the center of the rectangle).
If you want to scale the selection area up from the bottom left corner (green arrow in the image above), for example, grab the opposite handle in the top right corner (red arrow) and drag it outward (without holding the ctrl key).
You can hit the “Reset” button in the Scale tool dialogue box (red arrow in the image above) at any time to revert your selection area back to its original size.
To scale the selection down, click on any of the transform handles (red arrow in the image above) and drag your mouse inwards while holding the ctrl key (to scale it from the center). If you don’t want to scale from the center, simply release the ctrl key.
You can also move the selection area wherever you’d like by clicking on the four boxes in the center of the rectangle (red arrow in the image above) and dragging your mouse to the new location.
You can also of course manually set the new size of your selection area using the “Width” and “Height” fields inside the Scale dialogue box (outlined in green in the photo above).
Once you have scaled and moved your selection area, click the “Scale” button to apply the scale (red arrow).
Your newly scaled selection area will now appear (red arrow)! I recommend changing the Transform mode of your scale tool back to “Layer” once you are done to keep yourself from getting frustrated the next time you try to scale a layer with this tool (I have done this many times – forgetting my tool was in a different mode).
That’s it for this tutorial. If you liked it, you can check out all my GIMP Help Articles, GIMP Video Tutorials, or GIMP Premium Classes and Courses. You can also get more with a Premium Membership to Davies Media Design!