Reversible DCT-based data hiding in stereo images

Stereo images captured from a pair of CCDs simultaneously are widely used to create the illusion of 3D depth. Each pair of stereo images has many similar block pairs. In this paper, a novel reversible data hiding method is proposed to embed secret data in these similar block pairs. To increase the embedding capacity, each 3-bit secret data is first converted to a pair of integers. Then, similar block pairs are found based on the lower frequency DCT-quantized coefficients. Each converted integer is embedded via the difference of a pair of middle frequency DCT-quantized coefficients from these similar block pairs. It is worth mentioning that the proposed method is reversible, but the existing data hiding methods for stereo images are irreversible. Experimental results show that the proposed method is undetectable under Chi-square analysis, and it provides high embedding capacity while maintaining acceptable quality of stereo images higher than 30 dB. The experimental results also show that the proposed method outperforms Chang et al.'s method and Lin and Shiu's method in embedding capacity and image quality.