What’s a bitmap image?
If you think of ‘computer graphics’ as being the heading at the top of the tree, the next two headings would be vector graphics and bitmap graphics. Bitmap images are composed of a grid of pixels (squares) where each pixel has a colour. An important property of a bitmap image is its resolution – or the number of pixels per inch of image (also know as dots per inch – DPI). The higher the resolution, the better the quality of image. Another important factor is the number of colours the image can support – in most cases this is either 256 colours, or 16 million colours. With 16 million colours (‘true colour’) available, and usually upwards of 72 dpi, you can see how real-life can be represented on screen, i.e. photos. All onscreen photos and scanned images are bitmap images. The disadvantage of bitmap images is that it’s easy to lose definition by making changes to them, e.g. resizing, adding, deleting or changing colours.
