Apparatus for and method of embedding and extracting digital information and medium having program for carrying out the method recorded thereon

A digital information embedding/extracting apparatus of a type extracting inherent digital information embedded in a digital image signal, the apparatus comprising:

• band division means for receiving a reconstructed digital image signal obtained by dividing said digital image signal through discrete wavelet transform or sub-band division and by embedding a pseudo-random number string in a string structured by coefficients in every or some of a plurality of frequency bands exclusive of a lowest frequency band referred to as MRA (hereinafter, referred to as MRR), and then dividing the reconstructed digital image signal into coefficients in a plurality of frequency bands through discrete wavelet transform or sub-band transform;
• correlation value computation means for computing an inner product of the string structured by the coefficients in said MRR among said divided frequency bands and a predetermined pseudo-random number assumed to be embedded;
• pseudo-random number string determination means for determining said pseudo-random number string embedded in said digital image signal according to the value computed by said correlation value computation means;
• and
• information extraction means for extracting said inherent digital information mapped to said determined pseudo-random number string.

A method of embedding/extracting digital information of a type embedding inherent digital information in a digital image signal, the method comprising the steps of:

• dividing said digital image signal into coefficients in a plurality of frequency bands through discrete wavelet transform or sub-band division;
• mapping said inherent digital information to a pseudo-random number string;
• embedding said pseudo-random number string in a string structured by the coefficients in every or some of said divided frequency bands exclusive of a lowest frequency band referred to as MRA (hereinafter, referred to as MRR);
• and
• reconstructing the digital image signal in which said pseudo-random number string has been embedded by using said MRR and said MRA to which information embedding processing is subjected.

A method of embedding/extracting digital information of a type extracting inherent digital information embedded in a digital image signal, the method comprising the steps of:

• receiving a reconstructed digital image signal obtained by dividing said digital image signal through discrete wavelet transform or sub-band division and by embedding a pseudo-random number string in a string structured by coefficients in every or some of a plurality of frequency bands exclusive of a lowest frequency band referred to as MRA (hereinafter, referred to as MRR), and then dividing the reconstructed digital image signal into coefficients in a plurality of frequency bands through discrete wavelet transform or sub-band transform;
• computing an inner product of the string structured by the coefficients in said MRR among said divided frequency bands and predetermined pseudo-random number assumed to be embedded;
• determining said pseudo-random number string embedded in said digital image signal according to said computed inner product;
• and
• generating said inherent digital information mapped to said determined pseudo-random number string.

A recording medium on which a program to be run in a computer device is recorded, the program being for realizing an operational environment in said computer device comprising the steps of:

• dividing a digital image signal into coefficients in a plurality of frequency bands through discrete wavelet transform or sub-band division;
• mapping inherent digital information to a pseudo-random number string;
• embedding said pseudo-random number string in a string structured by transform the coefficients in every or some of said divided frequency bands exclusive of a lowest frequency band referred to as MRA (hereinafter, referred to as MRR);
• and
• reconstructing the digital image signal in which said pseudo-random number string has been embedded by using said MRR and said MRA to which information embedding processing is subjected.

A recording medium on which a program to be run in a computer device is recorded, the program being for realizing an operational environment in said computer device comprising the steps of:

• receiving a reconstructed digital image signal obtained by dividing said digital image signal through discrete wavelet transform or sub-band division and by embedding a pseudo-random number string in a string structured by coefficients in every or some of a plurality of frequency bands exclusive of a lowest frequency band referred to as MRA (hereinafter, referred to as MRR), and then dividing the reconstructed digital image signal into coefficients in a plurality of frequency bands through discrete wavelet transform or sub-band transform;
• computing an inner product of the string structured by the coefficients in said MRR among said divided frequency bands and a predetermined pseudo-random number assumed to be embedded;
• determining said pseudo-random number string embedded in said digital image signal according to said computed inner product;
• and
• generating said inherent digital information mapped to said determined pseudo-random number string.