Method for inserting and extracting watermark to JEPG compression image using AC Coefficient

摘要

The present invention provides a method for inserting and extracting a watermark into and from a JPEG compression image using AC coefficients, wherein the complexity problem of an existing watermarking algorithm is solved, and a watermark having high tenacity can be produced so that the watermark can be extracted even when several sorts of modifications or attacks are applied to the JPEG compression image. According to an aspect of the present invention to achieve the above-described purpose, the method for inserting the watermark into the JPEG compression image using AC coefficients comprises the steps of: generating a quantization table made of DCT coefficients quantized through a DCT step and a quantization step for an original image; inserting the watermark using only AC coefficients while excluding DC coefficients from the quantized DCT coefficients of the quantization table; and generating a JPEG compression image by encoding the quantization table. Here, in the step of inserting the watermark, a value which is not 0 can be found from the AC coefficients in the quantization table, and the least significant bit (LSB) value of the AC coefficients can be converted into 0 - 1, 1 - 0.