A Digital Watermarking Technique Using Discrete Wavelet Transform


Sneha Nargundkar


The data embedded on digital media  or distributed over the internet can easily be replicated without error,  putting  the rights of their owners  at risk. Even when encrypted for distribution, data can easily be decrypted and copied. One   way   to discourage illegal duplication is to insert a watermark into potentially vulnerable data in such a way that it is impossible to  separate  the  watermark from  the data.  Watermarking   dependency on  the  original image increases its robustness but at the same time we need to make sure that  the watermark   is imperceptible.   In this paper, we have presented a robust digital image watermarking scheme based on Discrete Wavelet Transform by embedding scrambled watermark in middle frequency subband. The imagescrambling is applied by Arnold Transform.  The  decomposition  is  done  with  Haar wavelet  and  direct  weighting   factor  is  used  in watermark embedding  and extraction process. The scheme results in exact recovery of watermark with standard  database  images  of  size  512x512,  giving Correlation Factor equal to 1 with PSNR values in the range of 53-60dB.