Perceptual Watermarking should take full advantage of the

results from human visual system (HVS) studies. Just

noticeable difference (JND), which refers to the maximum

difference that the HVS does not perceive, gives us a way to

model the HVS accurately. In this paper, we exploit a

combined JND model which represents additional accurate

perceptual visibility threshold profile to guide watermarking

for digital images.