Watermarking Technique Based On Arnold Transform
Digital Communication has increasing now. In the context of multimedia communication, digital images and videos have numerous applications in entertainment world like TV channel broadcasting. The rapid evolution of digital technology makes the development of reliable and robust schemes for protecting digital images, audio, text and video from piracy. In this work we have presented a watermarking technique in which watermark can be chosen from host image itself and can be embedded in it by scrambling its content by Arnold transform. Scrambling helps in increase in security from any attack and is not able to extract by attackers. First of all, watermark has been extracted as ROI region which can be selected by the user from any part of the image. Later image has been divided into small blocks which then decomposed further by DWT and approximation coefficient has been used to embed the watermark bits in them. Difference method has been used to select the coefficient to be used for embedding. In these secret keys has been used to store the information about block n umber and the co-ordinates of embedding location. A threshold has been applied in order to make watermarking method imperceptible in nature as it cannot be seen by naked eye in the stego image. Embedding capacity of the algorithm has been increased from existed algorithms as each block can be user iteratively according to threshold and more and more bits can be embedded in it. In the end, effect of some major attacks has been considered and evaluated and algorithms are able to extract most of the watermark. PSNR and NC values have been used to evaluate the algorithm effectiveness in such attacks.