The stamp icon in the GIMP toolbox represents the Clone tool, which draws pixels sampled from a source image using any of GIMP's brushes. In addition to using it as a basic stamping tool, you can achieve a number of interesting effects by selecting options from the toolbox menu. The Clone tool's alignment options control how your brush strokes sample pixels from the source image, enabling you to make precise corrections to a photo or paint image filters such as blur or lens distortion. By saving a custom brush in the GIMP Brushes folder, you can stamp basic patterns using the Clone tool.

Create a Custom Brush

Step 1

Create a new file, and then enter the width and height for your brush in the "Create a New Image" dialog. These dimensions should match your brush's smallest size, because you can increase them from the toolbox menu, but you can't make them smaller. If you don't need to create a custom shape for your stamp, skip to the next section.

Step 2

Use the Text, Paintbrush or other tool to draw a shape for your stamp. Alternatively, open an image from your computer, click “Image,” and then select “Scale Image” to scale it to the correct dimensions. If it's a color image, click “Colors,” and then select “Desaturate” to convert it to black and white. When converted to a brush, black areas make marks, white areas are inactive and gray areas have varying levels of opacity according to how dark they are.

Step 3

Click “File,” choose “Save As,” and then name your brush file. In the Save Image dialog, click “Select File Type,” and then choose “GIMP Brush.” Using the file browser window in the dialog sidebar, navigate to the “.gimp” folder in your user directory. Save the file in the Brushes folder.

Step 4

Click “Refresh” in the "Layers and Brushes" window to display your brush in the menu.

Use the Clone Tool

Step 1

Open an image from which you want to sample colors or patterns. To draw them into another file, open a separate file for editing.

Step 2

Select the "Clone" tool from the toolbox menu -- its icon is shaped like a traditional stamp -- and then select your brush from the "Brushes" menu. Hold down “Ctrl” and click the area of the source image from which you want to sample pixels. By default, the Clone tool's alignment is set to Fixed, and if you only want to stamp your brush's shape, this setting doesn't matter. To paint an area exactly the way it appears in the source image, choose “Registered” from the "Alignment" menu.

Step 3

Apply pixels to your canvas by left-clicking in the appropriate area. If the alignment is set to Fixed, each brush stroke samples pixels from the same origin point, following your cursor as you move the mouse and snapping back when you let go of the mouse button. If you select “Registered,” the Clone tool follows your cursor but doesn't snap back to the origin when you let go of the button, so you can copy your source image to any area of the canvas. This setting is useful for painting effects over part of your image while leaving other parts unaffected.