Hybrid image compression methods based on vector quantization and block truncation coding

Vector quantization (VQ) and block truncation coding (BTC) are two popular schemes for image compression. VQ has been widely used for its simplicity and low bit rate; on the other hand, BTC has the advantages of requiring little computational cost and providing high image quality. To put together the advantages of VQ and ETC, three hybrid methods based on VQ and ETC are proposed in this paper. According to our experimental results, it is shown that the first two methods of ours produce good image quality while keeping low bit rate. Meanwhile, the third method produces higher image quality while keeping acceptable bit rate. Also, these methods require little computational cost. In other words, our methods can be applied to diverse occasions according to their specific requirements. (C) 1999 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(99)00204-4].