A digital watermark is an invisible mark embedded in digital images

video or audio documents

which may be used for a number of different purposes including copyright protection

authentication and captioning. In this paper

we proposed a watermarking scheme that embeds watermarks in the local region of the image. This new idea that we name it local watermarking scheme

inserts watermarks into the wavelet domain of local regions of the image instead of entire image. We select some stable feature points in the image

and then use these points to identify the locations where we insert watermarks. When the image is cropped

the feature points in the remaining piece of the image will not change. We can extract watermark with the help of the remaining feature points. A special quantization procedure is used when we embed watermark bits into the wavelet coefficients of the sub image

and the watermark can be detected without knowing the original image. Experimental results show that the watermark scheme proposed in this paper is robust to cropping

and also has good robustness to compression

filtering

noise adding

and StirMark attack.