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

A method for embedding watermark into an image, comprising:

• generating a pseudo random sequence, the length of the pseudo random sequence is 2n;
• generating a watermark sequence by circular-shifting in a shift register said pseudo random sequence by the distance d;
• inverse wavelet-transforming said watermark sequence;
• multiplying said inverse wavelet-transformed watermark sequence by a coefficient representing watermark embedding strength;
• generating a watermark-embedded image by adding said multiplied watermark sequence to an original image in a spatial domain;
• cross-correlating said watermark-embedded image and said pseudo random sequence by circular-shifting in the shift register said pseudo random sequence;
• detecting a distance d′, wherein the distance d′ is a maximum cross-correlation value;
• and
• dividing the distance d′ by 2m to retrieve a quotient, wherein the quotient is embedded information.

A digital video recorder for embedding watermark into an image which is shot in real time, and recording the image, wherein embedding watermark into the image comprises:

• generating, by a processor, a pseudo random sequence, the length of the pseudo random sequence is 2n;
• generating, by the processor, a watermark sequence by circular-shifting said pseudo random sequence by the distance d;
• multiplying, by the processor, said watermark sequence by a coefficient representing watermark embedding strength;
• generating, by the processor, a watermark-embedded image in a frequency transformation domain by adding the multiplied watermark sequence to a wavelet-transformed original image;
• and
• generating, by the processor, a watermark-embedded image in a spatial domain by inverse wavelet-transforming said watermark-embedded image generated in the frequency transformation domain.