APPARATUS FOR EMBEDDING SECRET INFORMATION TO COMPRESSED IMAGE DATA, APPARATUS FOR EXTRACTING THE SECRET INFORMATION, SECRET DATA REWRITING APPARATUS, DECRYPTION APPARATUS, RESTORATION APPARATUS, AND SECRET DATA EMBEDDING CODING APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide an embedding apparatus of secret information to compressed image data that can efficiently embed secret data to the compressed image data and efficiently detect the secret data and to provide an extraction apparatus for extracting the secret information.

SOLUTION: The embedding apparatus of secret information to compressed image data comprises: a means 14 for partially decoding compressed image data; a quantization conversion coefficient extract means for extracting quantization conversion coefficients from the partially decoded data; a secret data insertion means 11 for embedding secret data 12 to particular null coefficients of the quantization conversion coefficients; and a means 15 for again applying partial coding to the quantization conversion coefficients to which the secret data are embedded. The secret data insertion means 11 utilizes the positional information or the amount of the particular quantization conversion coefficients for the secret data. Or the secret data insertion means 11 utilizes the values and the positions of the particular quantization conversion coefficients. Moreover, the positions of the particular quantization conversion coefficients are determined on the basis of the position of the last non-null conversion coefficient among the conversion coefficients.

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