Study Of Secret Image Sharing Scheme Based On JPEG Quantization Coefficients

Image sharing technology is the direct application of secret sharing in the area of image security. By increasing the image redundancy, the technology of image sharing can effectively solve the problem of easy to lose messages caused by a single carrier. The commonly used methods of image are PSS(Polynomial Style Sharing) scheme and RG(Random Grids) scheme. The former has better visual effects, but it has the problem of pixel expansion and sharing image size which is different in the original secret image. The most important is that it’s time complexity is O(nlogn) which is too large. The latter has a high efficiency; however, the quality of the reconstructed secret images is lower accordingly.To solve the problems mentioned above, the main contributions of this paper are described as follows:(1)According to the problem of sharing image size, this paper presents a new scheme for image sharing based on the JPEG quantized coefficients. This scheme uses a new method of randomly JPEG quantization coefficient matrices to generate the sharing images. It can ensure that all of the sharing images have the same size as the original secret image, the secret image size is no longer associated with the threshold value n anymore.(2)Differ from the traditional(k, n) threshold image sharing scheme, gray values larger than 250 are disposed without truncation in this paper. At the same time, none of the original secret pixels need special processing. The most important is the scheme proposed by this paper does not extend the original pixel d into n sub-pixels so that it has the smallest pixel expansion which is 1.(3)In this paper, the reveal phase only needs to use the XOR operation, and the time complexity is reduce to O(n). Compared with the time complexity of traditional(k, n) threshold image sharing scheme which is O(nlogn), this method can meet the demand of real-time performance. And this algorithm has both high efficiency and good visual effect.In this paper, we use the PSS scheme based on Lagrange interpolation and RG scheme based on superposed operation to do some comparative study. The results of multiple sets of comparative experiments show that the proposed scheme has a simple and effective way to achieve the sharing images, which have no pixel expansion and can keep the same size as the original secret image at the same time. The most important is that the proposed scheme has greatly improved the efficiency of the reveal phase.