Method for embedding watermark into an image and digital video recorder using said method

Abstract

The present invention relates to a method for embedding and detecting watermark wherein forgery/alternation of image can be identified and the location of forgery/alternation can be verified by embedding and detecting watermark into a digital image which is shot in real time. Watermark is generated by using a quantized coefficient after frequency transform used in the compression process. By embedding this into an image, image can be compressed simultaneously with embedding watermark. The present invention discloses a method for embedding robust watermark which embeds a random sequence circular shifted from an original pseudo random sequence by the distance d as watermark into an image. The present invention discloses a technology for generating and embedding watermark by using a DCT coefficient quantized during the process for MPEG compressing the image, wherein said watermark can be generated and embedded in a unit of macro blocks or slices. The present invention discloses a technology for generating and embedding watermark by using a wavelet coefficient quantized during the process for wavelet compressing the image. Further, the present invention discloses a digital video recorder recording the image which is shot in real time embedded with watermark in accordance with the above method for embedding watermark.

1 - 14 . (canceled) 
     
     
         15 . A method for embedding watermark into an image simultaneously with MPEG compression for the image, comprising:
 inputting quantized discrete cosine transformation (DCT) coefficient of a corresponding macro block in said image;   dividing each DCT block of said corresponding macro block into a signature extracting region and a watermark embedding region;   combining said quantized DCT coefficient in said signature extracting region with user information;   obtaining a hash value by regarding said combined value as an input value of the hash function; and   embedding said hash value into a least significant bit (LSB) of the quantized DCT coefficient in said watermark embedding region.   
     
     
         16 . The method according to  claim 15 , wherein said macro block has a size of 16×16, and said macro block includes 4 DCT blocks having a size of 8×8. 
     
     
         17 . A method for embedding watermark into an image simultaneously with MPEG compression for image, comprising:
 inputting quantized discrete cosine transformation (DCT) coefficients of all macro blocks in corresponding slice in said image;   dividing each DCT block of said macro blocks into the signature extracting region and the watermark embedding region;   combining said quantized DCT coefficients in said signature extracting region with user information;   obtaining hash value by regarding said combined value as an input value of hash function; and   embedding said hash value into a least significant bit (LSB) of quantized DCT coefficient in watermark embedding region in next slice of said corresponding slice.   
     
     
         18 . The method according to  claim 15 , wherein user information includes at least one of an unique number of a manufacturing company and an unique number of manufactured goods. 
     
     
         19 . The method according to  claim 15  wherein said watermark is fragile watermark. 
     
     
         20 . A digital video recorder for embedding watermark into an image which is shot in real time and for recording the image, wherein embedding watermark into an image shot in real time comprises:
 inputting quantized discrete cosine transformation (DCT) coefficient of a corresponding macro block in said image;   dividing each DCT block of said corresponding macro block into a signature extracting region and a watermark embedding region;   combining said quantized DCT coefficient in said signature extracting region with user information;   obtaining a hash value by regarding said combined value as an input value of the hash function; and   embedding said hash value into a least significant bit (LSB) of the quantized DCT coefficient in said watermark embedding region.   
     
     
         21 - 26 . (canceled)