Nowadays there is an explosion of multimedia information. A huge quantity of static and video images has been stored on the Internet. A large number of images stored on different media were converted to digital format. For example, TV images and newspapers have been converted to digital form, making an easy task their processing, distribution and storage.
More than 2700 digital pictures are made in every second (in total 85 billion images yearly). For example, PhotoWorks includes tens of millions of images on its web site. The common images are completed by special purpose images, like medical images with an estimation of 2 billion per year.