On watermarking in frequency domain

A wavelet-based image watermarking scheme is proposed, based on insertion of ‘logo’ image as watermark in mid-frequency domain. This new approach provides flexibility in determining the pixel to be watermarked and increases the data hiding capacity. It is easy to implement watermark embedding algorithm as well as the corresponding detection algorithm. The watermarking algorithm is tested under different attacks such as median filtering, image cropping and image compression. It is also robust. The experimental results prove that the method is more tamper proof and less perceptible for any type of images other than well known private methods in frequency domain. In the proposed approach, an original image is decomposed into wavelet coefficients then watermark is embedded through algorithm. The wavelet transform filters can be used as security key for the extraction of inserted watermark. The proposed watermark extraction technique is independent of the original image. The watermark embedded image is produced by taking the inverse 2-D discrete wavelet transform of the altered wavelet decomposition. Here we have given the relation between the area of the channel in which we insert the watermark and the area affected in original image.