Method and apparatus for digital watermarking

Abstract

A method for embedding digital watermark data in digital data contents includes the steps of obtaining a frequency coefficient of block data of digital data contents, obtaining a complexity of the block data, obtaining an amount of transformation of the frequency coefficient from the complexity and the digital watermark data, and embedding the digital watermark data by transforming the frequency coefficient. In addition, a method for reading digital watermark data includes the steps of calculating a probability of reading ‘1’ or ‘0’ in a read bit sequence by using a test method on the basis of binary distribution, determining the presence or absence of digital watermark data according to the probability, and reconstituting digital watermark data. Another method includes the steps of performing soft decision in code theory by assigning weights to the digital watermark sequence with a weighting function, and reconstituting digital watermark data.

1 - 2 . (canceled) 
   
   
       3 . A method for embedding digital watermark data in digital data contents, said method comprising the steps of:
 receiving said digital data contents and said digital watermark data;   dividing said digital data contents into block data;   obtaining a frequency coefficient of said block data by performing an orthogonal transform;   obtaining an amount of transformation of said frequency coefficient from said digital watermark data by using a quantization width corresponding to said frequency coefficient, said quantization width being obtained beforehand according to a manipulation method of said digital data contents based on difference values of frequency coefficients, obtained by using an orthogonal transform, between block data of original image data and block data that is obtained by manipulating said block data of said original image data with said manipulation, wherein said amount of transformation is obtained such that the larger is a change amount of said digital data contents due to processing by said manipulation methods, the larger is said amount of transformation;   embedding said digital watermark data in said digital data contents by transforming said frequency coefficient by said amount; and   generating watermarked digital data contents.   
   
   
       4 . The method as claimed in  claim 3 , wherein said quantization width is obtained by performing the following:
 dividing first digital data contents into one or a plurality of first block data;   dividing second digital data contents into one or a plurality of second block data, said second digital data contents being obtained by manipulating said first digital data contents with a predetermined manipulation method;   transforming said first block data and said second block data into first frequency coefficients and second frequency coefficients respectively by applying an orthogonal transform;   obtaining difference values between said first frequency coefficients and said second frequency coefficients for each frequency coefficient;   calculating a standard deviation of distribution of said difference values; and   obtaining said quantization width by multiplying said standard deviation by a watermark embedding strength.   
   
   
       5 - 8 . (canceled) 
   
   
       9 . An apparatus for embedding digital watermark data in digital data contents, said apparatus comprising:
 a computer readable medium having a computer program, which is executable by a processor, including:   a program code arrangement having program code for performing the following:
 receiving said digital data contents and said digital watermark data; 
 dividing said digital data contents into block data; 
 obtaining a frequency coefficient of said block data by performing an orthogonal transform; 
 obtaining a complexity of said block data; 
 obtaining an amount of transformation of said frequency coefficient from said digital watermark data by using a quantization width corresponding to said frequency coefficient, said quantization width being obtained beforehand according to a manipulation method of said digital data contents based on difference values of frequency coefficients, obtained by using an orthogonal transform, between block data of original image data and block data that is obtained by manipulating said block data of said original image data with said manipulation; 
 embedding said digital watermark data in said digital data contents by transforming said frequency coefficient by said amount; and 
 generating watermarked digital data contents; 
   wherein said amount of transformation is obtained such that the larger a change amount of said digital data contents due to processing by said manipulation method is, the larger said amount of transformation is.   
   
   
       10 . The apparatus as claimed in  claim 9 , wherein said quantization width is obtained by performing the following:
 dividing first digital data contents into one or a plurality of first block data;   dividing second digital data contents into one or a plurality of second block data, said second digital data contents being obtained by manipulating said first digital data contents with a predetermined manipulation method;   transforming said first block data and said second block data into first frequency coefficients and second frequency coefficients respectively by applying an orthogonal transform;   obtaining difference values between said first frequency coefficients and said second frequency coefficients for each frequency coefficient;   calculating a standard deviation of distribution of said difference values; and   obtaining said quantization width by multiplying said standard deviation by a watermark embedding strength.   
   
   
       11 - 14 . (canceled) 
   
   
       15 . An integrated circuit for embedding digital watermark data in digital data contents, comprising:
 a computer readable medium having a computer program, which is executable by a processor, including:   a program code arrangement having program code for performing the following:
 receiving said digital data contents and said digital watermark data; 
 dividing said digital data contents into block data; 
 obtaining a frequency coefficient of said block data by performing an orthogonal transform; 
 obtaining a complexity of said block data 
 obtaining an amount of transformation of said frequency coefficient from said digital watermark data by using a quantization width corresponding to said frequency coefficient, said quantization width being obtained beforehand according to a manipulation method of said digital data contents based on difference values of frequency coefficients, obtained by using an orthogonal transform, between block data of original image data and block data that is obtained by manipulating said block data of said original image data with said manipulation; 
 embedding said digital watermark data in said digital data contents by transforming said frequency coefficient by said amount; and 
 generating watermarked digital data contents. 
   wherein said amount of transformation is obtained such that the larger is a change amount of said digital data contents due to processing by said manipulation method, the larger is said amount of transformation.   
   
   
       16 . The integrated circuit as claimed in  claim 15 , wherein said quantization width is obtained by performing the following:
 dividing first digital data contents into one or a plurality of first block data;   dividing second digital data contents into one or a plurality of second block data, said second digital data contents being obtained by manipulating said first digital data contents with a predetermined manipulation method;   for transforming said first block data and said second block data into first frequency coefficients and second frequency coefficients respectively by applying an orthogonal transform;   obtaining difference values between said first frequency coefficients and said second frequency coefficients for each frequency coefficient;   calculating a standard deviation of distribution of said difference values; and   obtaining said quantization width by multiplying said standard deviation by a watermark embedding strength.   
   
   
       17 - 20 . (canceled) 
   
   
       21 . A computer readable medium storing a computer program for causing a computer system to embed digital watermark data in digital data contents, comprising:
 a program code arrangement having program code for performing the following:
 receiving said digital data contents and said digital watermark data; 
 dividing said digital data contents into block data by performing an orthogonal transform; 
 obtaining an amount of transformation of said frequency coefficient from said digital watermark data by using a quantization width corresponding to said frequency coefficient, said quantization width being obtained beforehand according to a manipulation method of said digital data contents based on difference values of frequency coefficients, obtained by using an orthogonal transform, between block data of original image data and block data that is obtained by manipulating said block data of said original image data with said manipulation; 
 embedding said digital watermark data in said digital data contents by transforming said frequency coefficient by said amount; and 
 generating watermarked digital data contents; 
   wherein said amount of transformation is obtained such that the larger is a change amount of said digital data contents due to processing by said manipulation method, the larger is said amount of transformation.   
   
   
       22 . The computer readable medium as claimed in  claim 21 , wherein said quantization width is obtained by a program code arrangement having program code for performing the following:
 dividing first digital data contents into one or a plurality of first block data;   dividing second digital data contents into one or a plurality of second block data, said second digital data contents being obtained by manipulating said first digital data contents with a predetermined manipulation method;   transforming said first block data and said second block data into first frequency coefficients and second frequency coefficients respectively by applying an orthogonal transform;   obtaining difference values between said first frequency coefficients and said second frequency coefficients for each frequency coefficient;   calculating a standard deviation of distribution of said difference values; and   obtaining said quantization width by multiplying said standard deviation by a watermark embedding strength;   wherein said amount of transformation is obtained such that the larger is a change amount of said digital data contents due to processing by said manipulation method, the larger is said amount of transformation.   
   
   
       23 . A computer readable medium storing a computer program for causing a computer system to read digital watermark data in digital data contents, comprising:
 a program code arrangement having program code for performing the following:
 for receiving said digital data contents; 
 dividing said digital data contents into block data; 
 obtaining a frequency coefficient of said block data by performing an orthogonal transform; and 
 generating digital watermark data from said frequency coefficient by using a quantization width corresponding to said frequency coefficient, said quantization width being obtained beforehand according to a manipulation method of said digital data contents based on difference values of frequency coefficients, obtained by using an orthogonal transform, between block data of original image data and block data that is obtained by manipulating said block data of said original image data with said manipulation; 
   wherein said amount of transformation is obtained such that the larger is a change amount of said digital data contents due to processing by said manipulation method, the larger is said amount of transformation.   
   
   
       24 . The computer readable medium as claimed in  claim 23 , wherein said quantization width is obtained by performing the following:
 dividing first digital data contents into one or a plurality of first block data;   dividing second digital data contents into one or a plurality of second block data, said second digital data contents being obtained by manipulating said first digital data contents with a predetermined manipulation method;   transforming said first block data and said second block data into first frequency coefficients and second frequency coefficients respectively by applying an orthogonal transform;   obtaining difference values between said first frequency coefficients and said second frequency coefficients for each frequency coefficient;   calculating a standard deviation of distribution of said difference values; and   obtaining said quantization width by multiplying said standard deviation by a watermark embedding strength;   wherein said amount of transformation is obtained such that the larger is a change amount of said digital data contents due to processing by said manipulation method, the larger is said amount of transformation.   
   
   
       25 - 72 . (canceled)