Graphics File Formats(Windows的.BMP .CUR .ICO文件的格式，有范例)

8 the bitmap has a maximum of 256 colors, and the bmcicolors member
contains 256 entries. in this case, each byte in the array represents a
single pixel.

24 the bitmap has a maximum of 2^24 colors. the bmcicolors member is
null, and each 3-byte sequence in the bitmap array represents the relative
intensities of red, green, and blue, respectively, of a pixel.

the biclrused member of the bitmapinfoheader structure specifies the number
of color indexes in the color table actually used by the bitmap. if the
biclrused member is set to zero, the bitmap uses the maximum number of colors
corresponding to the value of the bibitcount member.

the colors in the bmicolors table should appear in order of importance.
alternatively, for functions that use dibs, the bmicolors member can be an
array of 16-bit unsigned integers that specify an index into the currently
realized logical palette instead of explicit rgb values. in this case, an
application using the bitmap must call dib functions with the wusage
parameter set to dib_pal_colors.

note: the bmicolors member should not contain palette indexes if the bitmap
is to be stored in a file or transferred to another application. unless the
application uses the bitmap exclusively and under its complete control, the
bitmap color table should contain explicit rgb values.

see also

bitmapinfoheader, rgbquad

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bitmapinfoheader (3.0)

typedef struct tagbitmapinfoheader { /* bmih */
dword bisize;
long biwidth;
long biheight;
word biplanes;
word bibitcount;
dword bicompression;
dword bisizeimage;
long bixpelspermeter;
long biypelspermeter;
dword biclrused;
dword biclrimportant;
} bitmapinfoheader;

the bitmapinfoheader structure contains information about the dimensions and
color format of a windows 3.0 or later device-independent bitmap (dib).

member description

bisize specifies the number of bytes required by the
bitmapinfoheader structure.

biwidth specifies the width of the bitmap, in pixels.
biheightspecifies the height of the bitmap, in pixels.

biplanesspecifies the number of planes for the target device. this
member must be set to 1.

bibitcount specifies the number of bits per pixel. this value must be 1,
4, 8, or 24.

bicompression specifies the type of compression for a compressed bitmap. it
can be one of the following values:

value meaning

bi_rgb specifies that the bitmap is not compressed.

bi_rle8 specifies a run-length encoded format for bitmaps with 8 bits
per pixel. the compression format is a 2-byte format consisting of a count
byte followed by a byte containing a color index. for more information, see
the following comments section.

bi_rle4 specifies a run-length encoded format for bitmaps with 4 bits
per pixel. the compression format is a 2-byte format consisting of a count
byte followed by two word-length color indexes. for more information, see