Knowledge base: Knowledge can be as simple as detailing the regions of an image where information of interest is known to be located, thus limiting the search that must be conducted to search for information. The knowledge base can also be quite complex, such as a related list of all major possible defects in a materials inspection problem or an image database containing high-resolution satellite images of a region in connection with change detection applications. Applications of digital image processing :• Digital cameras generally include specialized digital image processing hardware (dedicated chips or circuits added on other chips) to convert raw data from the image sensor into a color-corrected image in a standard image file format. Images from digital cameras can be further processed to improve their quality or create desired special effects. This additional processing is usually performed by special software programs that can manipulate images in various ways. • Artistic effects are used to make images more visually appealing, to add special effects, and to create composite images. • Image processing techniques are widely used by law enforcement agencies License plate recognition for speed cameras/automated toll system, Fingerprint recognition. Enhancement of CCTV