Uncompressed raster image made up of a rectangular grid of pixels; each pixel is a different color (or level of gray for grayscale images), which together form an image; zooming in on a bitmap image will make it appear blocky since the size of each pixel increases.
View the BMP definition.
Program(s) that open bmp files
Mac: Apple Preview; Adobe Photoshop; Nuance OmniPage Pro X; Roxio Toast; The Logo Creator; Other image viewer Windows: Adobe Photoshop; Corel Paint Shop Pro; ACDSee Photo Manager; Microsoft Windows Photo Gallery Viewer; Nuance PaperPort; Nuance OmniPage Professional; Roxio Creator; The Logo Creator; Other image viewer
Information from FileInfo.com - The File Extensions Resource.
http://www.fileinfo.com/extension/bmp
