CGSociety :: Technology Focus
    8 September 2006, by Barbara Robertson

    Light Strokes launches their OptiPaint system, allowing completely tactile digital painting.

    There’s a wonderful air of “mad inventor” around Richard Greene, founder of Light Strokes, a small San Rafael, California-based company.

    Recently, the former street artist, MIT graduate, museum exhibit developer, and director of engineering for the MOTO product development group, rolled all that knowledge and experience into a radical new digital painting system that lets artists paint with real brushes. The product, OptiPaint, debuted at Photoshop World, being held in Las Vegas.

    Simply put, the product uses a video camera and a patented optical system to put onscreen, at 60 frames per second, the points of contact for something touching – moving on – the system’s “painting surface.”

    You can select colors and effects and then paint with your fingers, traditional brushes, sponges, string, paper printed with patterns, and so forth, even flowers and vegetables: You can, in fact, use any bright-colored object that you can wet and place on the transparent surface.

    Greene fills a drinking glass with water to illustrate how the system works, and then presses his fingertips against the side of the glass. “OK, now look in the glass,” he says. When we look into the water, we see his fingertips; only his fingertips. That, essentially, is what he captures with OptiPaint – internal reflections in a prism.
      The OptiPaint system seems an odd sidetrack from Greene’s MIT degree in biology until you follow his path.

    After graduation, he joined San Francisco’s Exploratorium, which houses hundreds of interactive exhibits on science, art and human perception. There, he developed exhibits with founder Dr. Frank Oppenheimer until 1982.

    At the same time, he worked on his own art, including those he calls “dendritic drawings,” that he sometimes reproduced with serigraphy – silkscreens. “The paint grew into dendrites,” he explains, as he points to a many-branched abstract organic drawing on his office wall.

    Eventually, he took his work to an art gallery. “They said, ‘You aren’t ready yet,’” he remembers. “So I asked them what they recommended. They suggested selling the prints on the street.”

    Greene saw this as an opportunity. He got a street artist’s license and for the next five years made his living by selling his water colors, dendritic drawings, and prints on the street and at art fairs. At first, before he knew what to do, he sold prints for $7 each. Later, he sold his work for several hundred dollars each.
    While at the Exploratorium, while he was creating his art using traditional tools, he began reading about the early computer paint systems.

    “They would say that an artist could pick a triangle shape or a circle shape for a brush and drag it,” he says. “But I was using a Japanese sumi brush. I started thinking about how to combine the expressiveness of traditional media with the power of computers.”

    At first, he made brushes – wands, really - using fiber optics, but he quickly discovered that the video camera captured everything around the brushes, too. So then, he filled a clear-bottomed tray with oil and painted in the oil.
    “Someone said, “If only you could get rid of the oil,’” Greene remembers. “So, one night I came up with the idea of using internal reflections in a prism.”
    Using that germ of an idea, Greene developed the first Light Strokes system as an Artist-in-Residence at the Exploratorium.


     The interactive public exhibit, now installed in several museums in addition to the Exploratorium, uses a glass-covered computer screen mounted in a tabletop. The system is 65” wide, 60” high, and 40” deep, and it weighs 200 pounds. Multiple visitors can interact simultaneously with the tactile system to produce digital art.

    “I not only got rid of the oil, I didn’t need the fiber optic brush,” Greene says. “I could use my fingers, hands, and any light-colored brush or object.” One of the big challenges in developing the system was in getting the high resolution both spatially and temporally for real time responsiveness. “The system needed to grab frames as quickly as possible and process them at 60 frames per second,” he says. Because computers weren’t yet fast enough, Greene developed his own image processor – a circuit board with “many chips.”

    Later, his experience at MOTO, where he worked with clients to develop products, helped him turn the idea into OptiPaint. That, and faster computers. OptiPaint, which includes his patented input device and Photoshop plug in, now works with off-the-shelf desktop computers and laptops. The painting surface is 10” by 7.5”; the hardware weighs 24 pounds.

    Greene eagerly demonstrates how he creates paintings with it. He selects green paint, wets his fist, rubs it across the painting surface, and thick, undulating curves of paint appear onscreen. A landscape. Then, he wets a brush and dabs the surface to add grass. He switches to another Photoshop layer and types “hello” in the sky above the landscape, changes layers again, and paints in clouds with a brush.

    In this painting, the strokes are segmented; each segment represents a captured frame. When he switches from textured mode to solid and moves more slowly, the segments nearly disappear. They’d disappear completely if he could do the processing in the video camera, he says, but he likes the textures.

    Next, he picks a new watercolor brush he’s discovered that comes with a built-in reservoir of water. When he pushes hard on the painting surface, he creates a thick brush stroke on screen just as he would if he were working on paper. Then, he wets and presses a piece of black cardboard with the word “OptiPaint” in white letters onto the surface. The letters transfer instantly to the screen. By sliding the cardboard, he paints with the letters. By saving each frame and converting the frames to a QuickTime movie, he creates motion graphics.

    So far, Greene has been the only user, so most examples of what artists can do with the system are his own abstract landscapes. That should change soon. “I can’t wait to see what other people do with the system,” he says. The OptiPaint hardware and together with the Photoshop Plug-In will sell for US$2,495.

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