| 摘要 |
PROBLEM TO BE SOLVED: To provide the method that codes/decodes an image in a way not perceptible by people but detectable by a decoding device by coding one possible value of a code system denoted by information of signal blocks having unique color modulation spatial pattern to all other signal blocks. SOLUTION: Each of signal blocks 32, 33 has a different spatial pattern consisting of four square sub areas having two different color modulation sets. This pattern denotes a value of a message data items coded by the signal block. A value '0' of the signal block 32 is coded and a value '1' of the signal block 33 is coded. The color modulation of each sub area is denoted by vector representation±δand produced according to both vectors of color space direction in a multi-dimensional color space and an amplitude of the related color modulation. In the color modulation, a total mean value of color difference amounts in the signal blocks 32, 33 is zero. Thus, the output signal is seen to have a means color or reference colors.
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