A new distortion-free data embedding scheme for high-dynamic range images

Distortion-free data embedding enables a cover image to be recovered from its stego-image without any distortion after the secret data have been extracted. This distortion-free property allows the appropriate recovery of highly sensitive images for which even the smallest modification of the cover images cannot be allowed. In this paper, a new distortion-free data embedding scheme is proposed for high-dynamic range (HDR) images. The proposed scheme uses all homogeneous representations of each pixel in an HDR image efficiently and effectively for data embedding to enhance the embedding capacity of the HDR cover image. First, in the embedding phase, all homogeneous representations are used, and each homogeneous representation is used to represent one pattern of secret bits. Then, to conceal the secret bits, the current homogeneous representation of the current processing pixel is modified by the corresponding homogeneous representation of the hidden secret bits. Experimental results confirmed that the proposed scheme has greater embedding capacity than three other existing schemes. In addition, the experimental results indicated that our scheme matched the visual quality of the stego-image by producing a tone-mapped cover image and its stego-image that were exactly the same. In other words, our scheme also provided the desired, distortion-free property.