Document Image Acquisition

Abstract

In the wider field of image processing and analysis the most common source of greylevel images is the CCD (Charge-Coupled Device) camera. This quite closely resembles a standard photographic camera; a lens at the front of the unit focuses light from the viewed environment onto a light sensitive surface within the camera body. In photography that surface is a section of photographic film. In CCD cameras, film is replaced by a rectangular array of light sensitive cells. When the shutter opens, each cell generates an electrical signal proportional to the amount of light falling upon it. These signals are fed out of the camera and into the computer via special purpose hardware which converts the analogue signals generated by the CCD array into a digital raster image.