What does a scanner do?

A scanner'sees'images and converts the printed text or pictures into electronic codes that can be understood by the computer. With a flatbed colour scanner, the paper with the image is placed face down on a glass screen, as with a photocopier. Beneath the glass are the lighting and measurement devices. Once the scanner is activated, it reads the image as a series of dots and then generates the digitized image that is sent to the computer and stored as a file.
The scanner operates by using three rotating lamps, each of which has a different coloured filter: red, green and blue.The resulting three separate images are combined into one by appropriate software.