Chapter 7 Color, Alpha Transparency, and the Quartz Graphics State

A color in Quartz consists of a color space, a set of component values, and an alpha value. The color space determines the number of color components and how the components are interpreted. The alpha value determines the transparency of a color. Alpha transparency is one of the distinguishing features of the Quartz drawing model. Not only does every color have an associated alpha value, but Quartz supports a global alpha, an additional transparency value that can be applied to all drawing.

Quartz offers a wide variety of color models for painting graphics. Because ColorSync color management is integrated into Quartz, it’s easy to use calibrated colors and color spaces for drawing, ...

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