Bitmap images are made up of pixels in a grid, these are small dots of colours which together form what is seen on the computer. Bitmap images are also known as raster images. Bitmap graphics are dependent on resolution. What resolution actually is, is the amount of pixels that are in an image, this is seen as dots per inch (dpi) or pixels (ppi). Common bitmap formats are such as, BMP (bitmap file format), GIF (Graphics Interchange format), JPG/JPEG (Joint Photographic Experts Group, PSD.