When it comes to expressing ideas and conveying information, mankind has always preferred

concrete visual means (images, painting) to more abstract counterparts (written text). This is

evident from the antiquity of the former methods compared to the latter. The recent spate

of technological advances in handling digital data have further strengthened our dependence on

visual modes of communication. This can, for instance, be witnessed in the explosively growing

amount of digital image data, especially with the proliferation of the world wide web.