Color It! for Mac

From Digimage Arts:

Color It! is an award-winning, fully-featured image editing program that opens a wide variety of file formats, offers 16 levels of undo, and supports pressure-sensitive tablets and Photoshop-compatible plug-ins for scanners and filters. A customizable tools palette, animated GIF and image map creation, clipping paths, levels, curves, CMYK four-color separations, and a bevy of built-in filters including ones to remove scratches, dust and red eye are just some of the powerful features. Work with existing images and photographs, scan in new ones, or create original works of art from scratch. Easily manipulate and blend images in ways limited only by your imagination!