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typedef struct tagRGBQUAD {
    BYTE rgbBlue;
    BYTE rgbGreen;
    BYTE rgbRed;
    BYTE rgbReserved;
} RGBQUAD;
 
The RGBQUAD structure specifies a logical color or a 16-bit color index. A
logical color specifies the color desired by an application. A color index
indirectly specifies a logical color by identifying a color in an array (or
table) of colors.
 
Member       Description
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rgbBlue      Specifies the intensity of blue. It must be a value in the
             range 0 (no blue) to 255 (brightest blue).
 
rgbGreen     Specifies the intensity of green. It must be a value in the
             range 0 (no green) to 255 (brightest green).
 
rgbRed       Specifies the intensity of red. It must be a value in the range
             0 (no red) to 255 (brightest red).
 
rgbReserved  Specifies whether the RGBQUAD structure specifies an RGB color
             or a 16-bit color index. If this member is zero, this is an RGB
             color. If this member is 0xFF, then the low 16 bits (rgbBlue
             and rgbGreen members) is a color index, not an RGB color.
 
Comments
 
When the colors are at minimum intensity (0,0,0), the result is black; when
at maximum intensity (255,255,255), the result is white; and when at half
intensity (127,127,127), the result is gray.
 
Primary colors can be combined to form new colors. For example, solid red
(0,0,255) and blue (255,0,0) can form purple (255,0,255). If a device cannot
display all the possible RGB color combinations, the device driver must map
given RGB color values to colors the device can display. For example, in a
black-and-white display with only one bit per pixel, the driver uses a
cutoff intensity at which all the RGB values above the intensity are white
and all below are black. One method used to compute the cutoff intensity is
to add the individual color intensities according to the following formula:
 
((5*rgbGreen+3*rgbRed+rgbBlue)+4)>>3
 
If the result is greater than 128, then all the RGB values above that
intensity will be white, and those below it will be black.
 
 
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