A method for approximation of image block is presented

based on a least squares fractal approximation by a Self Affine System。The computational cost is only equal to 2×M×N products and 4×M×N additions。The code of image block consists of the quantized fractal cofficients。This block coding of images is called as block fractal approximation code (BFAC)。Its compression ratio depends on the size of image block and quantization of fractal cofficients。BFAC for "Lena" image by 8×8 blocks is quantized to six bits and encodes to a comp ression ratio of 17.8:1

its encoding and decoding time is about 30 seconds in PC486?D X33。A f ter eight iterations of decoding

the reconstructive image look like the origin。Its greater speed and simplicity compared to other fractal transforms suggest its immediate applicability。