An image processing apparatus for embedding predetermined information in
an image includes an input unit for inputting the image, a division unit
for dividing the input image into plural image regions, a periodicity
generation unit for generating plural different periodicities, an
addition unit for adding a predetermined value to a pixel value of each
pixel in the image region divided by the division unit, on the basis of
the periodicity, and a selection unit for selecting the periodicity for
the addition from among the plural periodicities, in accordance with the
predetermined information. Thus, image quality deterioration is reduced
and an extraction error ratio at a time of extracting additional
information is also reduced in a method of embedding the additional
information in the image.