Multimedia content is largely visual and has been prone to copyright infringement. While advocating for visualization of data and information, there is a need to ensure that such products are protected. Numerous watermarking techniques, for the protection of digital content, exist but still are not able to adequately prevent compromization of security. To achieve the desired level of security, an improved watermarking has been developed that can withstand a spectrum of possible attacks such as file compression, aspect ratio changes, filtering, cryptographic and statistical attacks. Many existing watermarking methods do not perform well against affine transformation attacks that render the watermark, to a greater extend irretrievable or undetectable. This paper presents the Log-polar mapping approach that had demonstrated the capacity of building a domain that is invariant to affine transformation attacks. Validation of this new approach to watermarking that uses a new filtering method to find the rotation and translation parameters is shown and explained. The validation was performed by simulation using MATLAB software. Comparison of performance of the Log-polar mapping approach algorithm with other existing algorithms was done using PSNR (Peak Signal to Noise Ratio) values and results presented that were in favour of the newly developed Log-polar mapping Algorithm.

Keywords : Multimedia, Log-polar Mapping Algorithm, MATLAB, Watermarking, Security.