Abstract: In this paper，two robust digital watermarking algorithms based on image normalization and invariant centroid theory are proposed.In order to boost up the safety and the solidity of the watermark，it is scrambled and chaotically encrypted before embedded into the original image.Firstly，both of the two methods use image normalization and the invariant centroid theory to obtain its significant region from the normalized image，then the scrambling watermark images are embedded into the significant regions.Experimental results show that the two schemes are invisible and robust against geometric attacks，especially each scheme has its own advantages.