The BITMAPINFO structure defines the dimensions and color information for a Windows device-independent bitmap (DIB).
A device-independent bitmap consists of two distinct parts: a BITMAPINFO structure that describes the dimensions and colors of the bitmap, and an array of bytes that specify the pixels in the bitmap. The bits in the array are packed together, but each scan line must be padded with zeros to end on a LONG boundary. If the height is positive, the origin of the bitmap is the lower-left corner. If the height is negative, the origin is the upper-left corner.
A packed bitmap is a bitmap where the byte array immediately follows the BITMAPINFO structure. Packed bitmaps are referenced by a single pointer.
For more information about the BITMAPINFO structure and appropriate values for members of the BITMAPINFOHEADER and RGBQUAD structures, see the following topics in the Windows SDK documentation.