Most of the important retouching effects in GIMP are applied using brushes, so becoming an expert in brush control is essential for any good image editor. The most basic control of all is the size of your brush, and adjusting your brush should happen without stopping to think about it.
In GIMP, the simplest way to change brush size is using the keyboard shortcuts [ and ] to increase and decrease your brush size gradually. To change brush size more rapidly, hold down the Shift key while pressing either square bracket and the adjustment rate will multiply by 10.
But like most things in the image editing world, there are actually a few different pathways to achieve the same end result. Creating custom brush presets in the sizes you use most can give you a nice speed boost while editing, and keyboard shortcuts can adapt to fit your editing style.
Using the Tool Panel
To get complete control over your brush size, you’ll need to take a look at the brush settings for your currently selected tool. Each brush-based tool shares the same customization options, so it’s easy enough to learn all the panel settings for brush size, although I strongly suggest that you try to use keyboard shortcuts whenever possible.
Size is the most obvious one, but Aspect Ratio and Angle can combine to create oval brushes of any size, and Brush Dynamics can have a huge impact on brush size. As you adjust the settings on the panel, you’ll notice the circular brush cursor updates in size and shape to match.
Creating New Brush Sizes in GIMP
If you find yourself having to switch back and forth regularly between large and small brush sizes, it can be faster to create custom brush presets in the Brushes panel. Then you can swap sizes in a single click, instead of having to mash the square brackets repeatedly.
Start things off by finding the Brushes panel in the upper right corner of the GIMP window. If it’s not visible, open the Windows menu in the GIMP menubar, select the Dockable Dialogs submenu, and click on Brushes. The shortcut Ctrl + Shift + B will also open the Brushes panel.
At the bottom of the Brushes panel, select the button second from the left labeled Create new brush. The Brush Editor opens, allowing you to edit the size of your new brush, as well as all the other usual options you’d find in the brush section of the Tool panel.
Your preset will be automatically saved, and you can go back to the Brushes panel to find it. Create as many new brushes as you want, and use the Brushes panel to switch quickly between them as needed for each stage of your edit.
Even if these presets are just starting points that you tweak to your exact needs at the moment, they can still save you a lot of time during brush-based retouching tasks.
Customizing Your Brush Shortcuts in GIMP
If you’re not happy with the existing shortcuts for changing brush size in GIMP, you can always configure new shortcuts that fit better into your workflow. One popular technique is to reassign the mouse wheel to control brush size instead of using it to control zoom (since it can’t do both).
To view and customize your shortcuts, open the Edit menu and select Keyboard Shortcuts. If you’re using GIMP on a Mac, you’ll need to look in the GIMP application menu to find the link.
Search for “size” and scroll to find the appropriate settings. Click the middle Shortcut column for the command you want to change, and GIMP will wait to register your next keypress or mouse click as the new shortcut. Spin your mouse wheel in the desired direction, and click Save.
Of course, you can adjust this shortcut to anything you want if the mouse wheel doesn’t work for you, but you might need to remap an existing command to an unused key combination. The mouse wheel is used for zoom, by default, but GIMP has plenty of other zoom shortcut options already.
That’s everything you need to know about making a brush size bigger or smaller in GIMP! Practice those shortcuts, or customize them to your heart’s content and then practice, but always practice! Changing brush size will become something you don’t even have to think about, and your editing process will speed up dramatically.About Thomas Boldt