Using GIMP: Correcting and Touching Up Your Images - GIMP 2.6 for Photographers: Image Editing with Open Source Software - page 142

use this as a special effect.) This setting can be altered while drawing, after
defining the brush.
When you close the Brush Editor, the new brush is saved permanently in
the program. Your new brush can now be found in the Brushes window; just
click on its name whenever you wish to use it.
Create a total of seven new brush pointers with soft edges and diameters
of 25, 35, 45, 65, 85, 100, and 200 (i.e., set Radius to 11.5, 16.5, 21.5, 31.5, 41,5,
50, 100; remember: the resulting brush size will always be slightly bigger than
twice the indicated radius). This will give you a good array of brush choices.
Smaller soft round brushes sized from 1 × 1 to 19 × 19 were installed with
GIMP.
You can use the Brush Editor at any time to edit your custom brush
pointers or to create new ones. The maximum brush radius is 1000 px.
When setting the size for a brush in the Brush Editor , first use the sliders to
get an approximate size. Next, fine-tune your new brush by using the cursor
keys (arrows) or by typing the exact value desired in the text fields.
If you want to create more brushes with the same characteristics with
just a difference in diameter, the program offers you the option of copying
an existing brush. Choose the brush with the desired characteristics in the
Brushes window and then click the Duplicate brush button. This is the third
button from the left in the Brushes window.
The Brush Editor opens. Now you can customize your brush according
to your preference and give it a new name. The brushes provided by GIMP
can only be customized if they are duplicated and then changed to your
preference. The default brushes are write-protected and can't be altered.
GIMP offers a comfortable option to change the scale of the brush while
it is in use. You can do this with all tools that work with a brush pointer, such
as the Clone tool. You can change the size of the brush by adjusting the Scale
option in the tool settings. The size of the brush starts at the value 1 as a default
and the brush can be reduced and enlarged in scale. Unfortunately, you can
change the size only in decimal fractions. An indication of the diameter of the
new brush is lacking to date.
Importing Brush Pointers from Adobe Photoshop into GIMP
It is comparatively easy to import brush pointers from Adobe Photoshop or
Adobe Photoshop Elements into GIMP. You simply have to copy the brush set
files from Photoshop with the extension abr . You can find them in the Presets/
Brushes subdirectory of your Photoshop installation directory. Copy the file
into the brushes folder in your GIMP installation. (The entire path in Windows
is C:\Program\Gimp-2.X\share\gimp\2.0\brushes .)
You can find a variety of prepared brushes for Photoshop and GIMP as free
downloads on the Web. Simply enter the keywords “Photoshop” (or “GIMP”)
and “brushes” into your preferred search engine. I have also listed several Web
addresses for brushes in the section 3.11.6.