The Color Picker dialog box allows you to choose a specific color to be used for displaying a Sketchpad object, for displaying text in Sketchpad, or for changing any of the colors available on Sketchpad’s Color menu.
The Color Picker appears when you choose the Display | Color | Other command or when you click the Color Picker swatch on the Text Palette. It also appears when you click the Edit Color Menu button on the System panel of the Advanced Preferences dialog box.
The Color Picker dialog box allows you to specify a color in several different ways. The most common methods involve RGB (Red-Green-Blue) values and HLS (Hue-Luminance-Saturation or Hue-Lightness-Saturation) values.
The actual Color Picker dialog box is provided by the particular Macintosh or Windows operating system installed on your computer, and may differ from the sample dialog boxes shown in the subtopics.
To specify a color using RGB, you set numeric values for the red, green, and blue components of the color. These numeric values are most commonly expressed either in percentages or in a range from 0 to 255, with higher numbers for a color corresponding to the presence of more of that color in the mix. Thus 255 for red and 0 each for green and blue specifies the purest possible red. Setting all three values to 0 specifies black (no color at all), and setting all three values to 255 specifies white (the brightest color, with the maximum amount possible of all three components).
The three values of HLS (Hue, Luminance, and Saturation) also allow you to specify a color numerically. Hue determines the color, such as red, blue, or green. Luminance determines how light or dark the colors are, with the maximum value corresponding to white and the minimum value (zero) corresponding to black. Saturation determines how much of the color is present; high saturation corresponds to vivid colors, and low saturation to pale colors. A saturation value of 0 specifies gray, with the shade of gray determined by the luminance. The most vivid pure colors correspond to the midpoint of the luminance scale and maximum saturation.
An alternative system called HSV (Hue-Saturation-Value) is similar to HLS, with the difference that the most vivid pure colors correspond to the maximum of the V scale (rather than the midpoint of the L scale) at maximum saturation. In this system white corresponds to zero saturation and maximum value.