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 accuracy as to whether 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 of extracting digital watermark information from image data in which said digital watermark information including position and rotation information is embedded, comprising:

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

A computer data signal used 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, comprising:

• code signals for use in a rotation information searching step of 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;
• code signals for use in a position information searching step of performing processing for extracting said position information from said 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 accuracy as to whether said 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 code signals for use in a determining step of determining the position and rotation angle at which said digital watermark information is embedded in said image data, based on the confidence coefficient calculated in said calculating step.