SUMMARY: BMP files are uncompressed images, Windows bitmaps.
The BMP file extension normally represents that the file is an image. BMP files are normally used on Windows machines though many other operating systems have programs to view such files. BMPs can represent virtually any type of image imaginable, from photographs of cars to holiday clip-art.
BMP files are made up of pixels, tiny dots that represent color in an image. Some BMP files may only contain black-and-white images (1-bit), others images that have up to 16 colors (4-bit), other 256 colors (8-bit), some 65,536 colors (16-bit), and others 16 million (24-bit). The more colors that can be represented in a bitmap the larger the file.
You can shrink a bitmap's size to some extent and still retain much of the image quality. However, if you increase a bitmap's size, no new detail is automatically added. Thus, the more you resample a bitmap upward, the blockier and more jagged it will look as the pixels turn into larger blocks of the same color. This results in 'pixilated' low-quality images.
Virtually any image viewer/editor on Windows machines, and many on other operating systems, can view and edit bitmaps. BMP files are "uncompressed", meaning that computers perform no operations on these files to reduce their file size. Also, it means you can open and resave a bitmap as many times as you want and the file will remain looking the same (assuming you do not adjust the color depth), which is not the case for some other image file formats.
Link: Sample less-expensive photo editing software that support BMP files.
Windows users: NOTE that unless you have configured your computer with the file extension viewing tweak, it is possible that a filename that looks like it ends with ".bmp", especially one attached to an e-mail message, actually has a hidden OTHER extension, meaning that if you double-click the file, it may actually run a computer virus!
Return to the File Extensions page.
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