A Nearly Optimum Generalized Multilevel Block Truncation Coding Algorithms With a Fast Nonexhaustive Search Based on a Mean Square Error Criterion

Block Truncation Coding (BTC), using a one-bit moment preserving quantizer to quantize a block, is a simple compression method; however, compression with BTC cannot be used to obtain a sufficiently high quality image, especially an image with many edges. In this paper, a new generalized multilevel BTC algorithm, which arbitrarily specifies the number of quantization levels, is developed. In the proposed algorithm, a nearly optimum quantizer is proposed based on a multiplication-free and nonexhaustive search such that the computational complexity is very low. The simulation results indicate that both the computational complexity and the reconstructed image quality obtained using the proposed multilevel BTC algorithm are better than those obtainable with other existing multilevel BTC algorithms.