Robust Reference Watermarking(RRW)is a digital watermarking algorithm of still images based on the concept of multiresolution wavelet fusion.The concept of"Key points"is applied to watermarking in order to improve the robustness of RRW.Normal RRW uses only a constant

Q

to quantize wavelet coefficient.In the quantization process of improved method

if the watermark point is key point

then use larger quantizing parameter

Q

to quantize wavelet coefficient

else use smaller

Q

.When detecting watermark

key points'weight value are 1

and others'are constant not smaller than 0 and not larger than 1.Analysis is provided to compute the probability of false positive and false negative results.Experimental results show the performance of our method is better than the original RRW method and demonstrate its potential

for the robust watermarking of photographic imagery.