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Inside Macintosh: Advanced Color Imaging on the Mac OS /
Chapter 1 - Palette Manager


About the Palette Manager

You can use the Palette Manager to

Indexed devices (devices with a pixel depth of 8 bits or less) have default color lookup tables (CLUTs) that contain a broad spectrum of colors to meet the color needs of the widest range of applications. The Palette Manager allows you to customize the colors for each window in your application--within the limits of each display device's pixel depth. The Palette Manager can enhance your color display because it can give you a specialized range of colors to display. For example, on a device with an 8-bit pixel depth, instead of 256 colors spread across the spectrum, which is what the default CLUT provides, you could choose a particular range of colors depending on the image your application is displaying in a specific window. For one image you might provide 180 greens and the remaining 76 colors across the spectrum, or for a different image, 254 reds with black and white.

The Palette Manager compares your palettes with the CLUTs for the available display devices. For example, if a user opens your application's window or makes it active and frontmost on the desktop, the Palette Manager compares the colors of the palette you specified for your window with those available for the video card and loads whatever colors are needed into the color table of the card.

On direct devices, the Palette Manager uses the exact colors you request, to the limits of the card's pixel depth (15 or 24 bits per pixel). The use of palettes does not enhance the color display on direct devices because direct devices can display thousands or millions of colors, which means that sufficient colors are available for even the most skewed or narrow color scheme.


Subtopics
Palette Format
The Palette Paradigm
Colors in a Palette
How the Palette Manager Allocates Colors for Display
How the Palette Manager Restores the Color Environment

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© Apple Computer, Inc.
13 NOV 1996