A scanner is a device to scan an image or a document and convert s a hard copy in to a soft copy which can be further saved in the computer and edited. The saved image can be in the form of a jpeg, gif, bmp or any other format as per the requirements. Here’s how a regular image scanner works. A photograph which needs to be scanned is mounted on a rotating drum and then a collimated light beam is shot at the photo. After that a photocell is used to record the reflected light. The drum is then rotated to do the full scan of the image.