A comparison of the Z, E8 and Leech lattices for image subband quantization

Lattice vector quantization schemes offer high coding efficiency without the burden associated with generating and searching a codebook. The distortion associated with a given lattice is often expressed in terms of the G number, which is a measure of the mean square error per dimension generated by quantization of a uniform source. Subband image coefficients, however, are best modeled by a generalized Gaussian, leading to distortion characteristics that are quite different from those encountered for uniform, Laplacian, or Gaussian sources. We present here the distortion associated with Z, E₈, and Leech lattice quantization for coding of generalized Gaussian sources, and show that for low bit rates the Z lattice offers both the best performance and the lowest implementational complexity