A novel fractal block-coding technique for digital images

An approach to digital image coding, rooted in iterated transformation theory (ITT) and referred to as ITT-based coding, is proposed. It is a fractal block-coding method which relies on the assumption that image redundancy can be efficiently exploited through block self-transformability. The coding-decoding system is based on the construction, for any given original image to encode, of an image transformation of a special kind which (when iterated on any initial image) produces a sequence of images that converges to a fractal approximation of the original. The requirements on the transformation are that (i) it is contractive in the metric space of images endowed with the L₂ metric, (ii) it leaves the original image approximately invariant, and (iii) its complexity is smaller than that of the original image. The fully automated ITT-based system has comparable performance, in terms of signal-to-noise-ratio and bit rate, to state-or-the-art vector quantizers, with which it shares some features