During the development of JMP 7, I learned more than I ever wanted to know about color. At one extreme are the physicists studying optics and at another extreme are the biologists exploring color receptors and their connections to the brain. Somewhere in the middle is the study of the perception of color. What makes two colors look related? At what point does a color change from reddish to orangish? The simple models don't work too well to answer those kinds of questions, so color research has a psychological perspective with most new knowledge being gained from human experiments.
How does all this relate to JMP? Color is an important dimension of computer graphics, of course. Color can be used in a categorical way to represent distinct values, or it can be used in a continuous way to represent a scale of values. JMP has a general-purpose palette of 65 colors, organized as 5 shades of 12 hues, plus 5 achromatic shades.
JMP 6 palette (Windows/Linux version)
These are the colors conveniently available for graph markers, and the colors in the center row are the default colors for most categorical needs in JMP. In JMP 7, we have made minor updates to the palette to address some noted weak spots and have kept the overall structure of 5 shades by 12 hues for compatibility.
JMP 7 palette (Windows/Linux version)
Some of the hue spacing has changed so that, for instance, orange isn't as close to red as it was before, but the main change is in luminance. We've tried to make the colors in each row be more compatible in their luminance values. (What's luminance? Consider pure RGB green vs. pure RGB blue. They have the same magnitude in RGB space, but green is much more luminous -- has less contrast against white.) Previously, for instance, JMP's yellow was too light to see on a white background and blue was too dark to distinguish from black in some situations. Yellow is still lighter than blue, but now stands out better on a white background.
Of course, color perception depends a great deal on the environment and the observer, so the general-purpose palette is just a starting point. JMP 7 offers more ways to customize colors in your graphs. I'll explore those and other color features of JMP 7 in the next few postings.
If you want to know all about color models, I found a collection of informal and informative papers on color theory at handprint.com.
