This paper proposes a new steganographic method utilizing features of JPEG compression. The method embeds secret information using the number of zeroes in a block of quantized DCT coefficients in minimum coding units (MCU) of JPEG images. In the method, we can embed secret information into JPEG images with degradation like that by JPEG compression. Furthermore, the method causes little change of the histogram of quantized DCT coefficients, so it is hard to perceive secret information embedded by the method. The method mainly modifies boundaries between zero and non-zero DCT coefficients, so we can use the low frequency side of DCT coefficients for another steganographic method.

This letter proposes a method which can embed index data such as memos into JPEG images. The method embeds digital watermarks using the quantitative relation between quantized DCT coefficients in JPEG images. In the method, we can embed extra data to represent index data and can extract the index data without parameters used in embedding process. Furthermore, the method is tolerant of JPEG recompression and prevents the degradation of image quality by rewriting index data.