An image must be converted to numerical form before processing. This conversion process is called digitization, and a common form is illustrated in Figure (1). The image is divided into small regions called picture elements, or pixel for short. The most common subdivision scheme is the rectangular sampling grid shown in Figure (1). The image is divided into horizontal lines made up of adjacent pixels. At each pixel location, the image brightness are sampled and quantized. This 15 step generates an integer at each pixel representing the brightness or darkness of the image at that point. When this has been done for all pixels, the image is represented by a rectangular array of integer. Each pixel has a location or address (Line or row number and sample or column number) and an integer value called gray level. This array of digital data is now a candidate for computer processing.
