Improvement of JPEG compression efficiency using information hiding and image restoration

An application of information hiding to image compression is investigated to improve compression efficiency for JPEG color images, where entropy coded DCT coefficients of chrominance components are embedded into DCT coefficients of luminance component. In the proposed method, a color image is changed to a JPEG gray image with only luminance component. A color image can be recovered from the gray image by extracting chrominance components. To recover an image from degradation caused by compression and embedding, an image restoration method based on the MAP estimation is also applied. Experimental results show that information hiding improves compression efficiency slightly, image restoration improves it more than information hiding, and the use of both information hiding and image restoration is most effective to improve compression efficiency.