BITMAPINFOHEADER Structure

The BITMAPINFOHEADER structure contains information about the dimensions and color format of a device-independent bitmap (DIB).

Note   This structure is fully described in the Microsoft® Platform SDK. This entry is included in the DirectShow documentation for quick reference.

Syntax

typedef struct tagBITMAPINFOHEADER {
    DWORD  biSize;
    LONG   biWidth;
    LONG   biHeight;
    WORD   biPlanes;
    WORD   biBitCount;
    DWORD  biCompression;
    DWORD  biSizeImage;
    LONG   biXPelsPerMeter;
    LONG   biYPelsPerMeter;
    DWORD  biClrUsed;
    DWORD  biClrImportant;
} BITMAPINFOHEADER;

Members

biSize

Specifies the number of bytes required by the structure.

biWidth

Specifies the width of the bitmap, in pixels.

biHeight

Specifies the height of the bitmap, in pixels. If biHeight is positive, the bitmap is a bottom-up DIB with the origin at the lower left corner. If biHeight is negative, the bitmap is a top-down DIB with the origin at the upper left corner.

biPlanes

Specifies the number of planes for the target device. This value must be set to 1.

biBitCount

Specifies the number of bits per pixel. 

biCompression

Specifies the type of compression for a compressed bottom-up bitmap.

biSizeImage

Specifies the size, in bytes, of the image. This can be set to 0 for uncompressed RGB bitmaps.

biXPelsPerMeter

Specifies the horizontal resolution, in pixels per meter, of the target device for the bitmap.

biYPelsPerMeter

Specifies the vertical resolution, in pixels per meter, of the target device for the bitmap.

biClrUsed

Specifies the number of color indices in the color table that are actually used by the bitmap.

biClrImportant

Specifies the number of color indices that are considered important for displaying the bitmap. If this value is zero, all colors are important.

When the value in the biBitCount member is greater than eight, video drivers can assume bitmaps are true color and do not use a color table.

When the value is less than or equal to eight, video drivers can assume the bitmap uses a palette or color table defined in the BITMAPINFO data structure. This data structure has the following members:

typedef struct tagBITMAPINFO {
    BITMAPINFOHEADER bmiHeader;
    RGBQUAD          bmiColors[1];
} BITMAPINFO;

The BITMAPINFO bmiheader member specifies a BITMAPINFOHEADER structure. The BITMAPINFO bmiColors member specifies an array of RGBQUAD data types that define the colors in the bitmap.