High payload image steganography with minimum distortion based on absolute moment block truncation coding

This paper presents an improved image steganography scheme based on absolute moment block truncation coding (AMBTC). The purpose of the proposed scheme is to achieve high payload, good visual quality and low computation complexity at the same time. In the scheme, a threshold is predefined to classify the blocks of the AMBTC-compressed codes as smooth or complex blocks, in which data are then embedded. For the smooth blocks, the bit planes of them are used to embed the data. Later, the two quantization levels in the smooth block are re-calculated to minimize the distortion in image quality. For the complex blocks, a proportion of secret bits are concealed by exchanging the order of two quantization levels with together toggling the bit plane, by which the payload can be increased without any distortion. Furthermore, the proposed scheme inherits the advantages of the AMBTC method, such as pleasing image quality, ease to be implemented and low computational complexity. With adjustable threshold, the application of the proposed scheme becomes flexible, that means different thresholds can be used for different applications. Experimental results and analysis demonstrate the effectiveness and superiority of the proposed scheme.