METHOD OF ROBUSTNESS BLIND WATERMARKING FOR DIGITAL IMAGE USING DWT

摘要

The present invention relates to a method of robustness blind watermarking for a digital image using discrete wavelet transform (DWT) for inserting or extracting a watermark into or from a digital image. The method includes the steps of: (a) converting the digital image into a color format having a luminance component (Y); (b) performing n-level two-dimensional discrete wavelet transform (2DDWT) on the luminance component data to obtain most significant sub-bands; (c) calculating a weight, wherein the weight is set differently according to a coefficient distribution of the sub-band; (d) performing scrambling on a watermark to be inserted into the digital image; (e) amplifying and inserting the scrambled watermark in the most significant sub-band according to the weight as a result of performing the n-level 2DDWT; (f) performing inverse n-level 2DDWT on the sub-bands into which the watermark is inserted to restore the luminance component data; and (g) restoring an image having a color format including the restored luminance component to an original color format. According to the watermarking method as described above, the watermark insertion area can be expanded to the surrounding area by using the Fresnel transforming property, so invisibility, robustness and versatility can be ensured with respect to images having various resolutions and aspect ratios even under various pixel value changing attacks and geometric attacks.;COPYRIGHT KIPO 2017