Digital watermark embedding device, digital watermark detection device and recording medium recording computer readable program for realizing functions of two devices

Abstract

A digital watermark embedding device has an input section which inputs pixel value data of an image which is a target for embedding of watermark information, an embedded position selection section which determines a position in frequency domain into which the watermark information is to be embedded, irrespectively of a frequency component value, a frequency component value variation decision section which determines a variation of a frequency component value at each embedded position determined by the embedded position selection section, a pixel value variation calculation section which calculates a variation of a pixel value at each point in pixel value domain of the image based on the embedded position in frequency domain determined by the embedded position selection section and on the variation of a frequency component value determined by the frequency component value variation decision section, a pixel value conversion section which embeds watermark information by changing corresponding pixel value data of the image in accordance with the variation of a pixel value at each point in pixel value domain calculated by the pixel value variation calculation section, and an output section which outputs pixel value data of the image into which watermark information has been embedded.