Painting by computer is nothing new--for years, artists have used digital technologies to create their works. But most of those technologies focused on the product, not the process, so painting with a computer had little in common with painting on canvas.

Not anymore. William Baxter and Vincent Scheib, two Carolina computer science grad students working with computer science professors Ming Lin and Dinesh Manocha, have developed dAb, a computer painting system that works and feels like the real thing. "We're attempting to recreate the experience of painting -- the look, the feel, and the action of it," Baxter said.

In dAb, the artist's brush is a 3D stylus, and her canvas is the computer screen. The stylus provides force feedback, meaning it feels like a real brush moving on canvas, Scheib explained. The artist can choose one of several virtual brushes -- rounds, flats, brights, and more -- which the developers modeled to perform like real-life paint brushes. Brush shape alters as the artist increases or decreases pressure on the stylus. The "footprint" of each brush is modeled to be predictable and lifelike, so the artist can control complex brush strokes just as she could with real brushes.

dAb also allows the artist to load up her brush with complex blends of paint, and to apply them onto the canvas in predictable and realistic ways. When it's time to mix colors or clean a brush, the artist simply taps her keyboard's space bar, and out pops a virtual palette. Another tap brings back the canvas. The paint model is bi-directional -- paint can move from the brush to the canvas, and vice versa.

The researchers even factored in drying time: the artist can control the blending of new paint layers onto previously painted layers by allowing the paint to partially dry. She can dry the whole canvas instantly, or let dAb dry it slowly.

Best of all, dAb is so intuitive that an artist can grab the stylus and paint without training. "Artists using our brush really think of it as a real brush," Scheib said. "They move it like they would a real brush, and they really imagine that it's a real brush in the computer."

And what do artists think of dAb? "Bill and Vince have worked hard to make the program as realistic to actual painting as possible -- and I think they've definitely succeeded," Rebecca Holmberg said. "In some ways dAb even surpasses wet painting. The capability to dry the canvas at any time and having a button to undo minor mistakes -- that's an artist's dream."

"Our ultimate goal is to increase the quality of human-computer communication and to enhance the level of usability for computer interfaces such as dAb," Lin said.

"We also envision that a virtual brush model like this one will be incorporated into future computer painting software for training and education," Manocha added.

Find dAb on the web