During the course of about a decade, the digital image went from being a medium for scientists and specialists to the most popular method for creating and sharing pictures on the planet. The pace of technological advance in this fi eld has been astounding; the hardware required to process and store fi lm-quality images is readily available on the average home computer, and it is almost effortless to work with digital images, given the abundance of free, intuitive software packages, and the same is becoming true of fi le-based video formats.