The word “bitmap” refers to an image formed by a pattern of bits, rather than a pattern of lines. There are two kinds of bitmaps in the Windows environment:
Device-dependent bitmaps are composed of patterns of bits in memory that can be displayed on an output device. Because of the close correlation between the bits in memory and the pixels on the display device, a memory bitmap is said to be device-dependent. The arrangement of bits in memory depends on the output device in use.
Device-independent bitmaps (DIBs) describe the actual appearance of an image, rather than the way that image is internally represented by a particular output device. Because this external definition can be applied to any display device, it is referred to as device-independent.
The Document Imaging SDK specializes in the manipulation of device-independent bitmaps (DIBs).