Research On Blind Digital Watermarking Based On DCT And DWT

Digital watermarking techenonlogy for the shortcomings of traditional information encryption method.It can procide safe protection of copyright in these figures, the source authentication and integrity of effective technical suppor in open netwoek environment.This paper analyzes transforms the principle of the DCT and DWT, DWT domain is the time-frequency transform, a localized, DCT transform has to relevance, is the global transformation. By comparing the original image and the image attacked by JPEG compression, GAUSS noise and salt & pepper noise,3rd-order low-frequency DWT coefficient has a strong correlation. Therefore, an improved digital blind watermark embedding and detection method is presented. It adopts coefficient of low frequency energy of DWT as the embedded watermark energy coefficient parameters, the energy distribution of DCT as the embedding position parametrs. The watermarked image PSNR is 45.832dB, has a strong invisibitily. The embedded watermark is still able to extract in JPEG compression of 50%.At the cordition of 0.001 GAUSS noise (MSE=0), NC is 0.8659. At the cordition of 0.01 salt & pepper noise, NC is 0.8821.The result show a good robustness.A DWT Blind digital watermarking embedding and detection method by trembling 3rd-order DWT coefficient of low frequency energy is presented.Watermarked image PSNR is 43.511dB. Experimental results show that the above method has good transparency and better robustness on the condition attacked by the noise, JPEG compression and cropping.