Low bit-rate image coding techniques

This paper discusses the design of a matrix quantizer to be used to encode 1) homomorphically processed images, and 2) mean subtracted images. An image obtained by optical means is modeled as a product of the illumination and reflectance components. The illumination part is lowpass and the reflectance part which reveals the edge and texture details, is highpass. The homomorpphic system as applied to image processing consists of a logarithmic point transformation followed by linear filtering. Homomorphic processing achieves a simultaneous dynamic range reduction and contrast enhancement. A matrix quantizer operating on such processed images is shown to achieve bit rates as low as 0.16 bpp with acceptable quality.