To provide a watermark information extraction device 30, capable of quickly extracting water information from an image in which the watermark information is embedded.
The watermark information extracting device 30 is comprised of: a scanner unit 300 for converting a recorded material 64 of letters and/or images or the like into image data being electric data; a filter unit 302 for eliminating the low frequency components of luminance variation of pixels included in the image data; a dispersion calculation unit 308 for calculating the dispersion of the luminance value at each location of the image data in a unit area, in which the low frequency components of luminance variations are eliminated, by shifting predetermined dimensions of the unit area on the image data; an information extracting unit 304 for extracting watermark information, sequentially starting from a unit area whose luminance value is the highest, and an extraction result output unit 306 for outputting accordingly, when the watermark information extracting unit 304 extracts the watermark information.
YAMADA TAKAAKI
NAGAGAWA SHINOBU
