Color Models define the way in which a color is defined. In Xara LX you can define colors using these models:

RGB (Red-Green-Blue). Most often used by video cards to define colors.

CMYK (Cyan-Magenta-Yellow-Key). Favored by commercial printers. Cyan, Magenta, Yellow and Key (Black) are the colors of the inks used.

HSV (Hue-Saturation-Value). The "artists" method of defining colors. Hue is the pure pigment of the color, Saturation is the amount of white mixed into the color and Value is the amount of Black mixed into the color. Hue is measured in degrees representing the angle around a color wheel that sweeps from Red through Yellow, Green, Cyan, Blue, Magenta and back to Red again.

Gray scale defines colors as Black, White or shades of Gray.