Abstract: In order to improve the imperceptibility, robustness and embedding capacity of available reversible data hiding (RDH) in encrypted color images, a high capacity reversible data hiding method forencrypted color images was proposed. At its transmission end, firstly the color image was encrypted by logistic chaotic mapping encryption algorithm and separated into RGB three color channels, and the three channels were divided into blocks and processed by two-dimensional discrete cosine transform (2D-DCT). Then, its low-frequency region with better robustness was selected to embed secret information and its anti-attack performance was improved. Finally, pixel complementary method was adopted to embed large-capacity secret information. At the receiving end, the encrypted image was decrypted firstly and then the secret information was extracted and the original image was recovered by means of inverse process of information embedment. Experimental result showed that compared with the hiding methods available, the proposed method would have much better performance in connection with image quality, embedding capacity, robustness and encryption; and the embedding capacity could be adaptively selected. When the capacity reached to 1.15 bpp, the average value of peak signal-to-noise ratio would amount to 39.39 dB.

Key words: reversible data hiding, encrypted color image, two-dimensional discrete cosine transformation(2D-DCT), logistic chaotic mapping, adaptive embedding