Additive Watermarking in Filtered Satellite Images Using Alpha Blending

Abstract

Development of computer network creates many benefits in digital imaging area which is applicable in satellite imaging too. But this easy access provides virtually unprecedented opportunities to pirate copyrighted satellite images. Maintaining privacy and authenticity in satellite information is an essential requirement but unfortunately it is not possible to do this. It is sometime necessary to identify the copyright information of satellite images. In this case, digital watermarking may be a better tool for this identification. To form digital watermarking, we have to incorporate a special bit pattern into the main information which is useful to identify proper users. In the proposed scheme, a novel method of watermarking application using alpha blending has been discussed. For our research work, we have selected color satellite image which are watermarked with variable values of alpha. Before watermarking, we have filtered the satellite image as well as the cover image using Gauss filtering. As a result of filtering, noise has been eliminated from both the images. The pixel modification has been performed during processing with alpha blending on red, green and blue planes respectively. Using proper value of alpha, original satellite image can be retrieved from the digital watermarked image. We have used conventional quality checking method, PSNR, to analyze the quality of the retrieved image. Applying some post-processing work, this can be used in steganography process of satellite image.