ALLOCATING IMAGE FORMING METHOD, ITS PROGRAM AND SECRET IMAGE DECODING METHOD

摘要

PROBLEM TO BE SOLVED: To enable a secret image to be decoded in a state where each allocated image is completely or almost incognizable from a decoded image, by producing an allocated high-quality image embedded with consecutive multi-gradient-sequence gray-scale secret images without embracing the enormous cost of high-speed massive computation. SOLUTION: A second binarizing unit 20 for outputting a pixel value B1m, n of a second allocating image B1 is equipped with a decoding-time peripheral luminance value calculator comprising a decoding pixel value calculator 28 and a peripheral luminance value calculator 29. The decoding-time peripheral luminance value calculator calculates a luminance value dm, n at the periphery of a target pixel. A secret pixel embedding processor 26 calculates a tentatively determined pixel value B1tm, n, a luminance value Sm, n of a secret image S, and a pixel value B0m, n of a first allocating image B0; and further calculates the pixel value B1m, n of the second allocating image B1 using the peripheral luminance value dm, n. COPYRIGHT: (C)2007,JPO&INPIT