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Inside Macintosh: Advanced Color Imaging Reference /

Chapter 3 - ColorSync Manager Reference for Applications and Device Drivers / Constants and Data Types

Defining Color Spaces

Color Packing for Color Spaces

The ColorSync Manager bitmap CMBitMap data type (page 3-61) includes a field that identifies the color space in which the color values of the bitmap image are expressed. The following enumeration defines the types of packing for a color space's storage format. The enumeration also defines an alpha channel that can be added as a component of a color value to define the degree of opacity or transparency of a color. These constants are combined with abstract data color space constants (page 3-23) to create values that identify a bitmap's color space (page 3-26). Your application does not specify color packing constants directly.

enum {
   cmNoColorPacking  = 0x0000,
   cmAlphaSpace      = 0x0080,
   cmWord5ColorPacking= 0x0500,
   cmLong8ColorPacking= 0x0800,
   cmLong10ColorPacking= 0x0a00,
   cmAlphaFirstPacking= 0x1000,
   cmOneBitDirectPacking= 0x0b00
   cmAlphaLastPacking= 0x0000,
   cm24_8ColorPacking= 0x2100,
   cm32_8ColorPacking= cmLong8ColorPacking,
   cm40_8ColorPacking= 0x2200,
   cm48_8ColorPacking= 0x2300,
   cm56_8ColorPacking= 0x2400,
   cm64_8ColorPacking= 0x2500,
   cm32_16ColorPacking= 0x2600,
   cm32_32ColorPacking= 0x2700
};

Enumerator descriptions

cmNoColorPacking

This constant is not used for ColorSync bitmaps.

cmAlphaSpace

An alpha channel component is added to the color value.

cmWord5ColorPacking

The color values for three 5-bit color channels are stored consecutively in a 16-bit word, with the highest order bit unused.

cmLong8ColorPacking

The color values for three or four 8-bit color channels are stored consecutively in a 32-bit long. For three channels, this constant is combined with either cmAlphaFirstPacking or cmAlphaLastPacking to indicate whether the unused eight bits are located at the beginning or end.

cmLong10ColorPacking

The color values for three 10-bit color channels are stored consecutively in a 32-bit long, with the two highest order bits unused.

cmAlphaFirstPacking

An alpha channel is added to the color value as its first component.

cmOneBitDirectPacking

One bit is used as the pixel format. This storage format is used by the resulting bitmap pointed to by the resultBitMap field of the CWCheckBitMap function (page 3-123); the bitmap must be only 1 bit deep.

cm24_8ColorPacking

The color values for three 8-bit color channels are stored in consecutive bytes, for a total of 24 bits.

cm32_8ColorPacking

The color values for four 8-bit color channels are stored in consecutive bytes, for a total of 32 bits.

cm40_8ColorPacking

The color values for five 8-bit color channels are stored in consecutive bytes, for a total of 40 bits.

cm48_8ColorPacking

The color values for six 8-bit color channels are stored in consecutive bytes, for a total of 48 bits.

cm56_8ColorPacking

The color values for seven 8-bit color channels are stored in consecutive bytes, for a total of 56 bits.

cm64_8ColorPacking

The color values for eight 8-bit color channels are stored in consecutive bytes, for a total of 64 bits.

cm32_16ColorPacking

The color values for two 16-bit color channels are stored in a 32-bit word.

cm32_32ColorPacking

The color value for a 32-bit color channel is stored in a 32-bit word.