REVERSIBLE COLOR-TO-GRAY MAPPING WITH RESISTANCE TO JPEG ENCODING

The use of a reversible color-to-gray algorithm is an effective technique in practical applications, in terms of running cost, data quantity, security, etc. Most conventional image processing approaches cannot apply image encoding to color- embedded gray images. In this study, we propose a reversible color-to-gray method with resistance to JPEG encoding. To embed color information, the discrete cosine transformation (DCT) is employed, with good affinity to JPEG encoding. In the proposed method, first an input color image is converted to the YCbCr color space, and the DCT coefficients of the Cb and Cr components are embedded into the DCT coefficients of the Y component. Then using the JPEG quantization table, an appropriate embedding position is determined. Experiments were performed on standard color images, and the color recovery error after JPEG coding was compared and verified with conventional methods using PSNR and CIEDE2000.