Image steganography based on Kirsch edge detection

Conventional steganography methods fabricate the secret information into the cover pixels without analyzing the pixel intensities of an image. As a result, some minor pixel level manipulations may lead to huge visual distortion in the stego-image. To this end, in this paper, a novel steganographic scheme based on Kirsch edge detector is proposed. The aim of the scheme is to maximize the payload by embedding more secret bits into edge pixels and fewer bits into the non-edge pixels. The proposed scheme has three major phases: construction of edge image, embedding and extraction. The first phase deals with the construction of masked image from the cover image, and in turn, edge image from the masked one. The second phase deals with the decomposition of the cover image into a set of triplet of pixels and then embedding of (x + y + 1) bits of secret data into each triplet of pixels to obtain the stego-image. Here, ‘x’ and ‘y’ are not fixed as the edge information of each triplet changes incessantly. The third or last phase deals with the extraction of the secret information from the stego-image using the reverse process. Simulation results on some standard images ensure that the proposed method achieves higher payload and better image quality compared to the conventional steganographic schemes. Furthermore, the Kirsch edge detector is able to produce more number of edge pixels compared to the traditional edge detectors; and, hence the proposed scheme also outperforms the existing edge-based methods in terms of payload.