Lossless Information Hiding in Images

5.5. Lossless Data Hiding in Block Truncation Coding–Compressed Color Images

As we know, BTC [1] is a lossy compression technique that can significantly reduce the size of digital images with acceptable visual quality. The traditional color BTC method compresses each color image block (typically 4 × 4) into three high means, three low means, and three bitplanes. To conceal secret data into color BTC compression codes as well as reducing the number of bitplanes, Chang et al. [5] used the genetic algorithm (GA) to generate an optimal common bitplane (replacing the traditional three bitplanes) to reduce the bit rate, and then utilized the side match distortion concept to increase the embedding capacity. However, Chang et al.'s method is time consuming ...