Improved reversible data hiding in encrypted images using histogram modification

Inspired by Zhang et al.'s method that applies the integer discrete wavelet transform (DWT) to the original image, and embeds the secret data into the middle (LH, HL) and high (HH) frequency sub-bands of integer DWT coefficients with histogram modification based method, we propose a reversible data hiding method that embeds the secret data into the encrypted prediction error values. Compared with the LH, HL and HH integer DWT coefficients, the prediction error values generated by our proposed method are more concentrated to 0, and thus a high visual quality of the marked decrypted image can be achieved. Experimental results show that our proposed method has a better performance than Zhang's.