All Things Painter Six Degrees of Expression by John Derry

In 1985, when I started working in the paint software development business, the technology was nascent to say the least. The difference between the tools named Pen and Brush were that the pen drew a continuous one-pixel line and the brush rendered large circles that separated into individual elements if you drew too fast.

The first digitizing tablets that we used were borrowed from the realm of computer-aided design (CAD). These tablets were designed to input points on engineering drawings into a CAD system. They had a stylus that was attached to the tablet by a wire. For some maddening reason, their designers chose a wire length just short enough to make it nearly impossible to place the stylus at a natural drawing angle. It reminded me of the tethered pens found in the lobby of a bank. It was frustrating!

There was no pressure-sensitivity associated with this generation of tablets. Who needed pressure-sensitivity to input points from a set of engineering plans? Regardless, these borrowed tablets represented a breakthrough when applied to a paint software and hardware system. They replaced the mouse as the drawing instrument. A mouse is a great pointing device, but drawing with one is like drawing with a bar of soap. A stylus, on the other hand, is similar in balance to many art-making tools: pencils, pens, brushes, etc. By starting with a shape and weight that is comfortable to hold in your hand, a stylus made it infinitely easier to associate the marks streaming from this device with the artistic media they attempted to mimic.

Early attempts to add pressure-sensitivity were, at best, partially successful. One early pressure-enabled tablet had an outboard box with a knob on it. As the temperature of the electronics varied, so did the pressure-sensitivity of the tethered stylus. The artist had to use the knob to constantly re-calibrate the pressure response. It was not the most elegant solution, but it provided a hint of how powerful the input of pressure-sensitivity could be when applied to painting tools.

Everything changed in 1988 with the arrival of the Wacom® cordless pressure-sensitive pen and tablet. Here was a stylus with no wires attached. And it didn't use batteries. It was like a magic trick! By removing the tethered cable, Wacom had an elegant solution for artists using early painting software. The feel of a Wacom stylus in the hand is very natural and reminiscent of traditional expressive mark-making tools. Today, we've grown so accustomed to Wacom's technology that we almost take it for granted.

The various spatial movements associated with an artist's hand, wrist, and arm motion are referred to as the six axes of motion. It is the artist's unique and unconscious blend of these spatial metrics that constitutes personalized expressive marks. Either individually, or in combination, these axes can be used to describe the location and attitude of a stylus in relation to a tablet surface. Essentially, this is the data that streams from a Wacom tablet and is utilized by Corel® Painter™. Let's take a look at how the various axes are interpreted by Corel Painter.

Imagine an invisible grid on the surface of your tablet. The horizontal and vertical lines represent the X and Y positional axes. Using these coordinates, you can precisely identify where your stylus is in relation to the tablet surface. The Z positional axis represents depth. When you apply pressure to the stylus, you are invoking the Z axis.

As an artist creates expressive strokes, the tilt and bearing of the stylus changes relative to the tablet. Tilt and bearing represent the 4th and 5th axes of motion. Up until very recently, the preceding five axes of motion comprised all of the data supplied to Painter by the Wacom tablet. The final axis, barrel rotation, was added with the release of the Wacom 6D Art Pen. This pen additionally transmits data pertaining to the rotation of the pen barrel relative to the tablet.

With the addition of barrel rotation, all six degrees of the artist's hand motion can be communicated to Corel Painter. What this means to us as artists is that all of our subtle expressive nuances are now capable of being captured in high fidelity. And this translates into greater expressive range. Have you ever known an artist that was worried about being too expressive?

The availability of the Wacom 6D Art Pen (which must be used in conjunction with a Wacom® Intuos® 3 tablet) does not automatically mean that Corel Painter will be more responsive to your input. It will be necessary to build barrel rotation, where desirable, into future brush variants. A set of five rotation-aware variants are shipped with the Wacom 6D Art Pen. Additional variants are sure to follow. For the brush building savvy, the Rotation parameter is available for use in the various Expression pop-up menus scattered throughout the Brush Control palettes.

As one who has been involved with the development of expressive software for the past two decades, the ability to capture all six degrees of hand-mediated expression represents a technological high-water mark. It will be interesting to see what new brushes are lurking around the bend.

Now, please excuse me while I rotate my barrel.

John Derry
Somewhere in Kansas

John Derry is a pioneer of digital painting and one of the original authors of Corel® Painter™. Since 1985, John has leveraged his background in drawing and painting to advance the look and experience of traditional art-making tools on the computer. John has a bachelor's degree and a master's degree in Fine Art and is a practicing artist and photographer. He is the Art Director at Strauss Peyton Imaging, a fine art printing company. John's Web site is at www.pixlart.com.