A hybrid watermark insertion method includes the steps of dividing the
digital image into a low frequency region and a high frequency region
using an edge map of the digital image; inserting a watermark into the
low frequency region of the image by employing a watermarking method
using a human visual system (HVS); and inserting the watermark into the
high frequency region of the image by employing a quantization index
modulation (QIM) method. A hybrid watermark extraction method includes
the steps of estimating a reference value used when inserting a
watermark, and searching a maximum value of correlation coefficients in
an image of the watermark image while changing the estimated reference
value within a designated range, to thereby find out the watermark
insertion method. Accordingly, the watermark insertion method can be
easily identified, thereby enabling the watermark extraction in a more
readily manner.