Whether you're drawn to open-source software's philosophy or its low price, you can find a capable, free image editor that can help you do everything from retouching digital photos to creating original sketches and vector illustrations.

These four open source image editors are suitable for serious use.

GIMP is the most widely used of the full-featured image editors, sometimes called Photoshop alternatives, available in the open source community. The GIMP interface can be confusing at first, especially if you have used Photoshop, since each tool palette floats independently on the desktop.

If you look closely, you'll see that GIMP offers a rich and robust array of image editing features, including photo editing, drawing and painting tools, and built-in plugins that include options for blurring, distortion, lens effects, and more.