BMP Image Format Analysis

BMP Format Images

Since all machines on the market support the Windows system, it's essential to understand some basic Windows operating system knowledge.

▲ BMP (Bitmap File) is the graphic file format used by Windows, and all image-processing software running in the Windows environment supports the BMP format.

▲ All internal graphics-rendering operations in Windows are based on BMP.

▲ BMP files prior to Windows 3.0 were device-dependent, so this format is called DDB (device-dependent bitmap).

▲ After Windows 3.0, BMP files became device-independent, so the format is known as DIB (device-independent bitmap).

*(Note: Even after Windows 3.0, DDB bitmaps still exist in the system. Functions such as BitBlt are based on DDB. However, when saving images to BMP files on disk, Microsoft strongly recommends using the DIB format, so that Windows can display stored images on any type of display device.)*

▲ The default file extension for BMP bitmap files is .BMP or .bmp (sometimes .DIB or .RLE is used).

▲ File Structure

A bitmap file can be considered as consisting of four parts:

★ Bitmap file header

★ Bitmap information header

★ Color table

★ Bitmap data (the image data array, also called *Data Bits* or *Data Body*)