LOGCOLORSPACE

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

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.

    Value Meaning
    LCS_CALIBRATED_RGB Color values are calibrated RGB values. The values are translated using the endpoints specified by the lcsEndpoints member before being passed to the device.
    LCS_sRGB Color values are values are sRGB values.
    LCS_WINDOWS_COLOR_SPACE Color 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.

    Value Intent ICC Name Meaning
    LCS_GM_ABS_
    COLORIMETRIC    		 Match Absolute Colorimetric Maintain the white point. Match the colors to their nearest color in the destination gamut.
    LCS_GM_
    BUSINESS    		 Graphic Saturation Maintain saturation. Used for business charts and other situations in which undithered colors are required.
    LCS_GM_
    GRAPHICS    		 Proof Relative Colorimetric Maintain colorimetric match. Used for graphic designs and named colors.
    LCS_GM_
    IMAGES    		 Picture Perceptual Maintain 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

**  Windows NT/2000/XP/Vista:** Included in Windows NT 4.0 and later.
**  Windows 95/98/Me:** Included in Windows 95 and later.
**  Header:** Declared in Wingdi.h.
**  Unicode:** Declared as Unicode and ANSI structures.

See Also

RGB, CMYK, BITMAPV4HEADER, BITMAPV5HEADER