Optimal digitization of 2-d images

The problem of representing an image by M × N samples with b bits/sample, subject to the constraint of a fixed total number of bits, is discussed. Reasonable assumptions are made in such a way that the optimization problem has a closed form solution. The solution is tested experimentally and agrees well with human perception of visual quality. The analytical solution brings out the dependence of the optimal digitization on image characteristics very clearly. The results explain and agree with results of other subjective tests.