IMAGE PROCESSING METHOD AND APPARATUS, AND PRINTED MATTER

摘要

PROBLEM TO BE SOLVED: To enhance the reliability of reading an electronic watermark. SOLUTION: The image processing method of this invention includes: a step 202 of converting a color space of original image data 100; a step 204 of embedding patch information to the original image data; a step 210 of applying Fourier transform to image data 101 to which the patch information is embedded and extracting amplitude information 111 and phase information 112; a step 218 of attaching a hash value to watermark information 120 and applying error correction coding to the information 120; a step 220 of applying spread spectrum processing to the information 120 to obtain watermark information 121 subjected to the spread processing; steps 242, 244 and 246 of creating a weight mask from the image data 101 to which the patch information is embedded and composing the weight mask, the amplitude information 111 and the spread watermark information 121; and a step 262 of decoding the color space.