Next: I.7 CMYK color system Up: I. Color Space: The Previous: I.5 Artificial illumination Contents Index

# I.6 Thinking in RGB or HSV

The RGB system is understandable because it is cartesian, and we all learned cartesian coordinates in school. But it doesn't help us create a tint or shade of a color; we cannot say, ``We want orange, and a lighter shade of orange, or a less vivid orange''. With HSV we can do this, by saying, ``Orange must be between red and yellow, so its hue is about = 30°; a less vivid orange has a lesser , a darker orange has a lesser ''. On the other hand, the HSV system is a peculiar geometric construction, more like a cone (Figure I.3). It is not an orthogonal coordinate system, and it is not found by a matrix transformation of RGB; these make it difficult in some cases too. Note that a move toward black or a move toward white will change both and , in the general case of an interior point in the cube. The HSV system also doesn't behave well for very dark colors, where the gray point is near black and the two lines we constructed above are almost parallel. If you are trying to create nice colors for drawing chocolates, for example, you may be better off guessing in RGB coordinates.

Next: I.7 CMYK color system Up: I. Color Space: The Previous: I.5 Artificial illumination Contents Index