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LOGCOLORSPACE Structure

The LOGCOLORSPACE structure contains information that defines a logical color space.

Syntax

typedef struct tagLOGCOLORSPACE {
  DWORD         lcsSignature;
  DWORD         lcsVersion;
  DWORD         lcsSize;
  LCSCSTYPE     lcsCSType;
  LCSGAMUTMATCH lcsIntent;
  CIEXYZTRIPLE  lcsEndpoints;
  DWORD         lcsGammaRed;
  DWORD         lcsGammaGreen;
  DWORD         lcsGammaBlue;
  TCHAR         lcsFilename[MAX_PATH];
} LOGCOLORSPACE, *LPLOGCOLORSPACE;

Members

lcsSignature

Color space signature. At present, this member should always be set to LCS_SIGNATURE.

lcsVersion

Version number; must be 0x400.

lcsSize

Size of this structure, in bytes.

lcsCSType

Color space type. The member can be one of the following values.

ValueMeaning
LCS_CALIBRATED_RGBColor values are calibrated RGB values. The values are translated using the endpoints specified by the lcsEndpoints member before being passed to the device.
LCS_sRGBColor values are values are sRGB values.
LCS_WINDOWS_COLOR_SPACEColor values are Windows default color space color values.

 

If LCS_CALIBRATED_RGB is not specified, the lcsEndpoints member is ignored.

lcsIntent

The gamut mapping method. This member can be one of the following values.

ValueIntentICC NameMeaning
LCS_GM_ABS_COLORIMETRICMatchAbsolute ColorimetricMaintain the white point. Match the colors to their nearest color in the destination gamut.
LCS_GM_BUSINESSGraphicSaturationMaintain saturation. Used for business charts and other situations in which undithered colors are required.
LCS_GM_GRAPHICSProofRelative ColorimetricMaintain colorimetric match. Used for graphic designs and named colors.
LCS_GM_IMAGESPicturePerceptualMaintain contrast. Used for photographs and natural images.

 

lcsEndpoints

Red, green, blue endpoints.

lcsGammaRed

Scale of the red coordinate.

lcsGammaGreen

Scale of the green coordinate.

lcsGammaBlue

Scale of the blue coordinate.

lcsFilename

A null-terminated string that names a color profile file. This member is typically set to zero, but may be used to set the color space to be exactly as specified by the color profile. This is useful for devices that input color values for a specific printer, or when using an installable image color matcher. If a color profile is specified, all other members of this structure should be set to reasonable values, even if the values are not completely accurate.

Remarks

Like palettes, but unlike pens and brushes, a pointer must be passed when creating a LogColorSpace.

If the lcsCSType member is set to LCS_sRGB or LCS_WINDOWS_COLOR_SPACE, the other members of this structure are ignored, and WCS uses the sRGB color space. The lcsEndpoints,lcsGammaRed, lcsGammaGreen, and lcsGammaBlue members are used to describe the logical color space. The lcsEndpoints member is a CIEXYZTRIPLE that contains the x, y, and z values of the color space's RGB endpoint.

The required DWORD bit format for the lcsGammaRed, lcsGammaGreen, and lcsGammaBlue is an 8.8 fixed point interger left-shifted by 8 bits. This means 8 interger bits are followed by 8 fraction bits. Taking the bit shift into account, the required format of the 32-bit DWORD is:

00000000nnnnnnnnffffffff00000000

Whenever the lcsFilename member contains a file name and the lcsCSType member is set to LCS_CALIBRATED_RGB, WCS ignores the other members of this structure. It uses the color space in the file as the color space to which this LOGCOLORSPACE structure refers.

The relation between tri-stimulus values X,Y,Z and chromaticity values x,y,z is as follows:

x = X/(X+Y+Z)

y = Y/(X+Y+Z)

z = Z/(X+Y+Z)

If the lcsCSType member is set to LCS_sRGB or LCS_WINDOWS_COLOR_SPACE, the other members of this structure are ignored, and ICM uses the sRGB color space. Appliations should still initialize the rest of the structure since CreateProfileFromLogColorSpace ignores lcsCSType member and uses lcsEndpoints, lcsGammaRed, lcsGammaGreen, lcsGammaBlue members to create a profile, which may not be initialized in case of LCS_sRGB or LCS_WINDOWS_COLOR_SPACE color spaces.

Requirements

Minimum supported client

Windows 2000 Professional

Minimum supported server

Windows 2000 Server

Header

Wingdi.h

See Also

RGB
CMYK
BITMAPV4HEADER
BITMAPV5HEADER

 

 

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Build date: 11/16/2010

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