1. A system for transmitting a digital image over a communication network, comprising: (a) an image storage device for storing a digital image; (b) a client computer coupled to the communication network, wherein the client computer generates and transmits across the communication network coordinates defining a region of interest within the digital image; (c) a server computer, coupled to the communication network and the image storage device, wherein the server computer performs the steps of: (i) pre-processing the digital image through a lossless wavelet transformation; (ii) receiving the coordinates from the client computer; and (iii) progressively transmitting to the client computer the region of interest within the digital image defined by the coordinates.