Image processor and image processing method

An image processor capable of extracting digital watermark information from image data in which said digital watermark information including position and rotation information is embedded, comprising:

• rotation information searching means for performing processing for extracting said rotation information from the image data with said digital watermark information embedded therein, for a plurality of rotation angles different from one another;
• position information searching means for performing processing for extracting said position information from said image data, for a plurality of start-of-extraction positions different from one another;
• calculating means for calculating confidence coefficients indicating the accuracy with which said position and rotation information is extracted, for each information searched by said rotation information searching means and position information searching means and extracted as position and rotation information;
• and
• determining means for determining the position and rotation angle at which said digital watermark information is embedded in said image data, based on the confidence coefficient calculated by said calculating means.

An image processing method comprising:

• an embedding step of embedding in image data digital watermark information comprising an irrotationally symmetric pattern arrangement, and including position and rotation information;
• a rotation information searching step for performing processing for extracting the rotation information from the image data with the digital watermark information embedded therein, for a plurality of rotation angles different from one another;
• a position information searching step for performing processing for extracting the position information from the image data, for a plurality of start-of-extraction positions different from one another;
• a calculating step for calculating confidence coefficients indicating the accuracy with which the position and rotation information is extracted, for each information searched by said rotation information searching step and said position information searching step and extracted as position and rotation information;
• and
• a determining step for determining the position and rotation angle at which the digital watermark information is embedded in the image data, based on the confidence coefficient calculated by said calculating step.

An image processing method of extracting digital watermark information from image data in which the digital watermark information including position and rotation information is embedded, comprising:

• a rotation information searching step of performing processing for extracting the rotation information from the image data with the digital watermark information embedded therein, for a plurality of rotation angles different from one another;
• a position information searching step of performing processing for extracting the position information from the image data, for a plurality of start-of-extraction positions different from one another;
• a calculating step of calculating confidence coefficients indicating the accuracy with which the position and rotation information is extracted, for each information searched in said rotation information searching step and position information searching step and extracted as position and rotation information;
• and
• a determining step of determining the position and rotation angle at which the digital watermark information is embedded in the image data, based on the confidence coefficient calculated in said calculating step.

A computer program product embodying a program comprising:

• program codes for implementing an image processing method of embedding in image data, digital watermark information comprising an irrotationally symmetric pattern arrangement and position and rotation information;
• program codes for a rotation information searching step for performing processing for extracting the rotation information from the image data with the digital watermark information embedded therein, for a plurality of rotation angles different from one another;
• program codes for a position information searching step for performing processing for extracting the position information from the image data, for a plurality of start-of-extraction positions different from one another;
• program codes for a calculating step for calculating confidence coefficients indicating the accuracy with which the position and rotation information is extracted, for each information searched by the rotation information searching step and position information searching step and extracted as position and rotation information;
• and
• program codes for a determining step for determining the position and rotation angle at which the digital watermark information is embedded in the image data, based on the confidence coefficient calculated by said calculating step.

A computer program product embodying a program for implementing an image processing method of extracting digital watermark information from image data in which said digital watermark information including position and rotation information is embedded,

• the program comprising:
• program codes for a rotation information searching step of performing processing for extracting the rotation information from the image data with the digital watermark information embedded therein, for a plurality of rotation angles different from one another;
• program codes for a position information searching step of performing processing for extracting the position information from the image data, for a plurality of start-of-extraction positions different from one another;
• program codes for a calculating step of calculating confidence coefficients indicating the accuracy with which the position and rotation information is extracted, for each information searched in the rotation information searching step and position information searching step and extracted as position and rotation information;
• and
• program codes for a determining step of determining the position and rotation angle at which the digital watermark information is embedded in the image data, based on the confidence coefficient calculated in the calculating step.

A computer data signal embodied in a propagating wave comprising:

• code signals for use in implementing an image processing method of embedding in image data, digital watermark information comprising an irrotationally symmetric pattern arrangement and position and rotation information;
• code signals for use in a rotation information searching step for performing processing for extracting the rotation information from the image data with the digital watermark information embedded therein, for a plurality of rotation angles different from one another;
• code signals for use in a position information searching step for performing processing for extracting the position information from the image data, for a plurality of start-of-extraction positions different from one another;
• code signals for use in a calculating step for calculating confidence coefficients indicating the accuracy with which the position and rotation information is extracted, for each information searched by the rotation information searching step and the position information searching step and extracted as position and rotation information;
• and
• code signals for use in a determining step for determining the position and rotation angle at which the digital watermark information is embedded in the image data, based on the confidence coefficient calculated by the calculating step.

A computer data signal embodied in a propagating wave and used for implementing an image processing method of extracting digital watermark information from image data in which the digital watermark information including position and rotation information is embedded comprising:

• code signals for use in a rotation information searching step of performing processing for extracting the rotation information from the image data with the digital watermark information embedded therein, for a plurality of rotation angles different from one another;
• code signals for use in a position information searching step of performing processing for extracting the position information from the image data, for a plurality of start-of-extraction positions different from one another;
• code signals for use in a calculating step of calculating confidence coefficients indicating the accuracy with which the position and rotation information is extracted, for each information searched in the rotation information searching step and the position information searching step and extracted as position and rotation information;
• and
• code signals for use in a determining step of determining the position and rotation angle at which the digital watermark information is embedded in the image data, based on the confidence coefficient calculated in the calculating step.