Image watermarking algorithm based on DWT

A new watermarking algorithm for digital images based on discrete wavelet transform (DWT) is proposed. The watermark used here is a text watermark. First, the 3-levelDWT is appliedto the host image and the watermark respectively. To ensure the security, the watermark should be encrypted ordisordered according to each subband. Then the different levels of the watermark frequency domain is repeatedly embedded into corresponding levels of the host image frequency domain in various places. Moreover, multiple extraction methods is presented to cope with various attacks. Experimental results have proved that the method is robust enough to some image degradation process such as resizing, cropping, JPEG or JPEG2000 compression.