Feature Based Watermarking Algorithm by Adopting Arnold Transform

The central idea of this paper is to develop an algorithm that embeds the watermark information in host image to authenticate it. The host image is divided into non-overlapping blocks of size 2x2. Minimum value is obtained from each block and the resultant matrix is scrambled for three times with Arnold transform to enhance security. From the transformed matrix a binary watermark is constructed and is embedded within the host image. The operation of embedding and extraction of watermark is done in high frequency domain of Discrete Wavelet Transform since small modifications in this domain are not perceived by human eyes. Furthermore, the proposed algorithm is checked against various common image processing attacks. This watermarking scheme deals with the extraction of the watermark information in the absence of original image, so the blind scheme was obtained.