Patent ID: 6704431
Filing Date: 2004-03-09
Classification: G06T,H04N

Abstract:
A method for reading digital watermark data embedded in digital data contents, said method comprising the steps of:receiving said digital data contents; determining threshold &agr; of reliability of digital watermark data which is read; obtaining a binary distribution function F(x) which represents a probability that a number x of â€˜1â€™ bits or â€˜0â€™ bits are included in a bit sequence which is read at random from digital data contents, said binary distribution function F(x) being obtained by using a probability q of reading â€˜1â€™ or â€˜0â€™ in said bit sequence and a repeating number of embedding each bit of digital watermark data; reading an ith digital watermark sequence of said digital watermark data from a digital watermark area of said digital data contents; calculating the number ki of â€˜1â€™ or â€˜0â€™ included in said digital watermark sequence; calculating a probability F(ki) by using said binary distribution function F(x); and reconstituting â€˜1â€™ or â€˜0â€™ from ith digital watermark data wi if F(ki)>&agr;, reconstituting â€˜0â€™ or â€˜1â€™ from ith digital watermark data wi if 1âˆ’F(ki)>&agr;, and determining that there is no watermark data or the presence is unknown if both of F(ki)>&agr; and 1âˆ’F(ki)>&agr; are not satisfied.