Abstract: Digital watermarking has been widely used for copyright protection of multimedia data. It is a process to provide authenticity by hiding a data into an image or audio or document. Hiding of data in an image can be done in frequency domain or spatial domain. In this paper we have made a comparative analysis on two frequency domain watermarking schemes. The first digital image watermarking algorithm utilizes texture block and edge detection in the discrete wavelet domain in order to balance between the invisibility and robustness and improve the ability of resisting to geometric attacks of the digital image watermark. The second method is a robust watermarking method based on Hadamard Transform. The simplicity of Hadamard transform offers a significant advantage in shorter processing time and ease of hardware implementation than most orthogonal transform techniques such as DWT and DCT. The two techniques are compared for better image quality and more robustness under various attacks such as JPEG compression, cropping, sharpening, and filtering and so on. Peak Signal to Noise Ratio (PSNR) and Normalized Correlation Coefficient (NCC) are computed to measure image quality and robustness.

Keywords: Discrete wavelet transform (DWT), Hadamard transform, Arnold Transform, Peak signal-to-noise ratio (PSNR).