Image processing apparatus and method

An image processing apparatus for embedding digital watermark information in an image, comprising:

• image input means for inputting frequency-transformed image data;
• inverse frequency transformation means for generating a watermark envelope ring pattern, which is expressed by a set of lines having an envelope ring pattern using amplitude component data obtained from the input image data, and phase component data;
• watermark pattern modulation means for modulating the amplitude component data and the watermark envelope ring pattern;
• and
• watermark pattern addition means for adding the modulated watermark pattern to the input image data.

An image processing method for embedding digital watermark information in an image, comprising:

• the image input step of inputting an image;
• the frequency transformation step of computing frequency transforms of the input image to convert the image into amplitude component data and phase component data;
• the embedding pattern generation step of generating an embedding pattern of digital watermark information, which is expressed by a set of lines having an envelope ring pattern, on the generated amplitude component data;
• the digital watermark embedding step of embedding digital watermark information at positions set on the lines in the embedding envelope ring pattern;
• and
• the inverse frequency transformation step of computing inverse frequency transforms of the amplitude component data embedded with the digital watermark information using the phase component data.

A computer program embeded on a computer-readable medium for controlling an image processing apparatus for embedding digital watermark information in an image, comprising:

• a program code of the image input step of inputting an image;
• a program code of the frequency transformation step of computing frequency transforms of the input image to convert the image into amplitude component data and phase component data;
• a program code of the embedding pattern generation step of generating an embedding pattern of digital watermark information, which is expressed by a set of lines having an envelope ring pattern, on the generated amplitude component data;
• a program code of the digital watermark embedding step of embedding digital watermark information at positions set on the lines in the embedding envelope ring pattern;
• and
• a program code of the inverse frequency transformation step of computing inverse frequency transforms of the amplitude component data embedded with the digital watermark information using the phase component data.