Improved Block Truncation Coding using Optimized Dot Diffusion

Block Truncation Coding (BTC) has been considered as a highly efficient compression technique for decades. However, the annoying blocking effect and false contour under low bit rate configuration are its key problems. In this work, an improved BTC, namely Dot-Diffused BTC (DDBTC), is proposed to solve these problems. On one hand, the DDBTC can provide excellent processing efficiency by exploiting the innate parallelism advantage of dot diffusion. On the other hand, the DDBTC can provide excellent image quality by co-optimizing the class matrix and diffused matrix of the dot diffusion. The experimental results demonstrate that the proposed DDBTC is fully superior to the pervious Error-Diffused BTC (EDBTC) in terms of image quality and processing efficiency, and has much better image quality than that of the Ordered-Dither BTC (ODBTC).