Covert Communication Technology Based On Mosaic Image Transmission

Combining mosaic technology with reversible data hiding technology is a new covert communication scheme,which disguises secret images into mosaic images with the appearance of concealed images.This new form of covert communication has played an important role in covert communications.However,the camouflage effect of the generated mosaic image is not good,and the image quality needs to be improved.Therefore,how to improve the visual quality of mosaic images is the main work in this paper.For grayscale images,we propose a covert communication algorithm based on grayscale mosaic image transmission.We improved the method of measuring image similarity,using a new similarity measure to cover image selection and block matching.When comparing the similarity of two images,we can not only take the global characteristics of the images as the measurement parameters,but also use the pixel-by-pixel comparison method to perform a quantitative measurement based on the pixel similarity.The experimental results show that the two images are more similar.So,the resulting mosaic image has better visual quality.For color images,we propose a covert communication algorithm for color mosaic image based on intensity adjustment.To this end,the secret image is converted to the HSI domain,and the intensity value data of the image blocks are replaced by the intensity value data of the cover image blocks for conversion into the RGB domain image.By doing this,the intensity value of the image can be adjusted.This adjustment makes the image look more smooth and natural.Thus,the visual quality of the mosaic image is significantly improved.Because of the large amount of side information,we use the multi-layer embedding method to embed the related information into the mosaic image.The experimental results show that the edge quality of the mosaic image is improved and visually more similar to the covert image.We used MATLAB to implement and test the proposed algorithms.Our algorithm is also compared with the traditional algorithms.Experimental results show that the quality of the mosaic image generated by this algorithm is superior to the traditional algorithms.This scheme is applied to secure transmission of secret images,which enhances the security and integrity of the secret image.The resulting system exhibits better covert communication effect.