Patent ID: 6829367
Filing Date: 2004-12-07
Classification: G06F,G06T

Abstract:
A content data judging apparatus, which determines whether a content data image prepared by a digital device was altered, comprising:(1) means for performing an authentication process using a medium on which content data are recorded and embedded with data for verifying pertinent content data wherein the content data image is divided into the segments or blocks arranged in pairs in which the data for verifying content is placed in bits selected by a random number sequence selected by a secret key; (2) means for reading said content data from said medium; (3) means for embedding, in said content data, the data for verifying the pertinent contents wherein said means (3) for embedding includes embedding the data for varying content in selected luminance element bit positions in segments of the content data images while the chroma bits are not changed, and wherein the embedding means adjusts the values of the coefficients (A1, A2, B1, B2, C1 and C2) selected from the two blocks in each pair I so that the relationship corresponds to the rules 1-1 and 1-2 herein below and is in accordance with the bit values of the data that corresponds to the individual pairs: When the bit value of data corresponding to a pair is 1: (A12&&B12&&C12)II (A1>A2&&B1>B2&&C12)II (A12&&B1>B2&&C1>C2)II (A1>A2&&B12&&C1>C2) . . . . (rule 1-1) When the bit value of data corresponding to a pair is 0: (A12&&B12&&C1>C2)II (A1>A2&&B12&&C12)II (A12&&B1>B2&&C12)II (A1>A2&&B1>B2&&C1>C2) . . . . (rule 1-2) wherein in the rules 1-1 and 1-2, X&&Y means both conditions X and Y are satisfied, and XIIY means either condition X or Y is satisfied;(4) means for extracting, from said content data, said data for verifying the pertinent contents; and (5) means for using the results of the extraction to determine whether said content data were altered by displaying as part of the content data image indicia indicating any portion of the image containing altered content data.