Digital image coding/decoding apparatus and method for recording and restoring a signature image using watermarking

A digital image coding method for recording a signature image on a host image using watermarking, comprising the steps of:

• receiving a host image and performing discrete wavelet transform thereon, and outputting M×M discrete wavelet coefficients, where M is a predetermined positive integer;
• receiving a signature image and performing discrete wavelet transform thereon, and outputting N×N discrete wavelet coefficients, where N is a predetermined positive integer smaller than M;
• receiving an encryption code for determining a predetermined rule for generating pseudo-random numbers and generating the pseudo-random numbers in accordance with the predetermined rule corresponding to the encryption code;
• selecting the replacing locations of N×N pixels using the pseudo-random numbers;
• and
• replacing the coefficients of the selected N×N pixel locations among M×M discrete wavelet coefficients with N×N wavelet coefficients, thereby outputting replaced M×M wavelet 20 coefficients.

A digital image decoding apparatus for restoring a signature image embedded on a host image using watermarking, comprising:

• a pseudo-random number generator operative to receive an encryption code and generate pseudo-random numbers in accordance with a predetermined rule according to the encryption code;
• a coefficient separation portion operative to set separating locations of N×N pixels using the pseudo-random numbers and separate the wavelet coefficients corresponding to the N×N pixel separating locations among M×M wavelet coefficients, and output separated N×N wavelet coefficients;
• and
• an inverse discrete wavelet transform portion operative to perform an inverse discrete wavelet transform using the separated N×N wavelet coefficients, and output a restored signature image.

A digital image decoding method for restoring a signature image embedded on a host image using watermarking, comprising the steps of:

• receiving an encryption code and generating pseudo-random numbers in accordance with a predetermined rule according to the encryption code;
• setting separating locations of N×N pixels using the pseudo-random numbers;
• separating the wavelet coefficients corresponding to the N×N pixel separating locations among M×M wavelet coefficients, and outputting separated N×N wavelet coefficients;
• and
• performing an inverse discrete wavelet transform using the separated N×N wavelet coefficients, and outputting a restored signature image.

A digital image codec apparatus for recording a signature image on a host image by using watermarking, and restoring the signature image from a watermarked image having the signature image embedded therein, comprising:

• a first discrete wavelet transform portion operative to receive a host image and perform a discrete wavelet transform thereon, and to output M×M discrete wavelet coefficients where M is a predetermined positive integer;
• a second discrete wavelet transform portion operative to receive a signature image and perform a discrete wavelet transform thereon, and to output N×N discrete wavelet coefficients, where N is a predetermined positive integer smaller than M;
• a first pseudo-random number generator operative to receive an encryption code for determining a predetermined rule for generating pseudo-random numbers and generate pseudo-random numbers in accordance with the predetermined rule corresponding to the encryption code;
• a coefficient replacement portion operative to select the replacing locations of N×N pixels using the pseudo-random numbers, and replace the coefficients of the selected N×N pixel locations among M×M discrete wavelet coefficients with N×N wavelet coefficients, and output replaced M×M wavelet coefficients;
• a second pseudo-random number generator operative to receive the encryption code and generate pseudo-random numbers in accordance with a predetermined rule corresponding to the encryption code;
• a coefficient separation portion operative to set separating locations of N×N pixels using the pseudo-random numbers, and separate the wavelet coefficients corresponding to the N×N pixel separating locations among M×M wavelet coefficients for the combined host image, and output N×N wavelet coefficients of the signature image;
• and
• an inverse discrete wavelet transform portion operative to perform an inverse discrete wavelet transform using the separated N×N wavelet coefficients, and output a restored signature image.

A computer readable medium including program codes executable by a computer to perform a digital image coding method for recording a signature image on a host image using watermarking, said method comprising:

• receiving a host image and performing discrete wavelet transform thereon, and outputting M×M discrete wavelet coefficients, where M is a predetermined positive integer;
• receiving a signature image and performing discrete wavelet transform thereon, and outputting N×N discrete wavelet coefficients, where N is a predetermined positive integer smaller than M;
• receiving an encryption code for determining a predetermined rule for generating pseudo-random numbers and generating the pseudo-random numbers in accordance with the predetermined rule corresponding to the encryption code;
• selecting the replacing locations of N×N pixels using the pseudo-random numbers;
• and
• replacing the coefficients of the selected N×N pixel locations among M×M discrete wavelet coefficients with N×N wavelet coefficients, thereby outputting replaced M×M wavelet coefficients.

A computer readable medium including program codes executable by a computer to perform a digital image decoding method for restoring a signature image embedded on a host image using watermarking, said method comprising:

• receiving an encryption code and generating pseudo-random numbers in accordance with a predetermined rule according to the encryption code;
• setting separating locations of N×N pixels using the pseudo-random numbers;
• separating the wavelet coefficients corresponding to the N×N pixel separating locations among M×M wavelet coefficients, and outputting separated N×N wavelet coefficients;
• and
• performing an inverse discrete wavelet transform using the separated N×N wavelet coefficients, and outputting a restored signature image.

A digital image coding apparatus for recording a signature image on a host image using watermarking, comprising:

• a first discrete wavelet transform portion operative to receive a host image and perform discrete wavelet transform thereon, and output a first plurality of discrete wavelet coefficients;
• a second discrete wavelet transform portion operative to receive a signature image and perform a discrete wavelet transform thereon, and output a second plurality of discrete wavelet coefficients, where the second plurality is a predetermined positive integer smaller than the first plurality;
• a pseudo-random number generator operative to receive an encryption code for determining a predetermined rule for generating pseudo-random numbers and generate the pseudo-random numbers in accordance with the predetermined rule corresponding to the encryption code;
• and
• a coefficient replacement portion operative to select the replacing locations of a second plurality of pixels using the pseudo-random numbers, and replace the coefficients of the selected second plurality of pixel locations among the first plurality of discrete wavelet coefficients with a second plurality of wavelet coefficients, and output a first plurality of replaced wavelet coefficients.

A digital image coding method for recording a signature image on a host image using watermarking, comprising the steps of:

• receiving a host image and performing discrete wavelet transform thereon, and outputting a first plurality of discrete wavelet coefficients;
• receiving a signature image and performing discrete wavelet transform thereon, and outputting a second plurality of discrete wavelet coefficients, where the second plurality is a predetermined positive integer smaller than the first plurality;
• receiving an encryption code for determining a predetermined rule for generating pseudo-random numbers and generating the pseudo-random numbers in accordance with the predetermined rule corresponding to the encryption code;
• selecting the replacing locations of a second plurality of pixels using the pseudo-random numbers;
• and
• replacing the coefficients of the selected second plurality of pixel locations among a first plurality of discrete wavelet coefficients with a second plurality of wavelet coefficients, thereby outputting replaced first plurality of wavelet coefficients.

A digital image decoding apparatus for restoring a signature image embedded on a host image using watermarking, comprising:

• a pseudo-random number generator operative to receive an encryption code and generate pseudo-random numbers in accordance with a predetermined rule according to the encryption code;
• a coefficient separation portion operative to set separating locations of a first plurality of pixels using the pseudo-random numbers and separate the wavelet coefficients corresponding to the first plurality of pixel separating locations among a second plurality of wavelet coefficients, and output a first plurality of separated wavelet coefficients;
• and
• an inverse discrete wavelet transform portion operative to perform an inverse discrete wavelet transform using the first plurality of separated wavelet coefficients, and output a restored signature image.

A digital image decoding method for restoring a signature image embedded on a host image using watermarking, comprising the steps of:

• receiving an encryption code and generating pseudo-random numbers in accordance with a predetermined rule according to the encryption code;
• setting separating locations of a first plurality of pixels using the pseudo-random numbers;
• separating the wavelet coefficients corresponding to the first plurality of pixel separating locations among a second plurality of wavelet coefficients, and outputting a first plurality of separated wavelet coefficients;
• and
• performing an inverse discrete wavelet transform using the first plurality of separated wavelet coefficients, and outputting a restored signature image.

A digital image codec apparatus for recording a signature image on a host image by using watermarking, and restoring the signature image from a watermarked image having the signature image embedded therein, comprising:

• a first discrete wavelet transform portion operative to receive a host image and perform a discrete wavelet transform thereon, and to output a first plurality of discrete wavelet coefficients;
• a second discrete wavelet transform portion operative to receive a signature image and perform a discrete wavelet transform thereon, and to output a second plurality of discrete wavelet coefficients, where the second plurality is a predetermined positive integer smaller than the first plurality;
• a first pseudo-random number generator operative to receive an encryption code for determining a predetermined rule for generating pseudo-random numbers and generate pseudo-random numbers in accordance with the predetermined rule corresponding to the encryption code;
• a coefficient replacement portion operative to select the replacing locations of a second plurality of pixels using the pseudo-random numbers, and replace the coefficients of the selected second plurality of pixel locations among a first plurality of discrete wavelet coefficients with a second plurality of wavelet coefficients, and output a first plurality of replaced wavelet coefficients;
• a second pseudo-random number generator operative to receive the encryption code and generate pseudo-random numbers in accordance with a predetermined rule corresponding to the encryption code;
• a coefficient separation portion operative to set separating locations of a second plurality of pixels using the pseudo-random numbers, and separate the wavelet coefficients corresponding to the second plurality of pixel separating locations among a first plurality of wavelet coefficients for the combined host image, and output a second plurality of wavelet coefficients of the signature image;
• and
• an inverse discrete wavelet transform portion operative to perform an inverse discrete wavelet transform using the second plurality of separated wavelet coefficients, and output a restored signature image.