The conception of digital image coding techniques is of great interest in various areas concerned with the storage or transmission of images. For the past few years, there has been a tendency to combine different classical coding techniques in order to obtain greater coding efficiency. In this paper, we propose an independent and novel approach to image coding, based on a fractal theory of iterated transformations. The main characteristics of this approach are that i) it relies on the assumption that image redundancy can be efficiently exploited through self-transformability on a block-wise basis, and ii) it approximates an original image by a fractal image. We, therefore, refer to our approach as fractal block coding. The coding-decoding system is based on the construction, for an original image to encode, of a specific image transformation-a fractal code-which, when iterated on any initial image, produces a sequence of images which converges to a fractal approximation of the original. We show how to design such a system for the coding of monochrome digital images at rates in the range of 0.5-1.0 b/pixel. Our fractal block coder has performance comparable to state-of-the-art vector quantizers, with which it shares some aspects. Extremely promising coding results are obtained.
