Abstract

In this paper, we present an introduction of digital image watermarking followed by important characteristics and potential applications of digital watermarks. Further, recent state-of-the-art watermarking techniques as reported by noted authors are discussed in brief. It includes the performance comparison of reported transform/spatial domain based watermarking techniques presented in tabular form. This comprehensive survey will be significant for researchers who will be able to implement more efficient watermarking techniques. Moreover, we present a robust watermarking technique using fusion of discrete wavelet transform and Karhunen-Loeve transform for digital images. Further, visual quality of the watermarked image is enhanced by using different image de-noising techniques. The results are obtained by varying the gain factor, size of the image watermark, different DWT sub-bands, and image processing attacks. Experimental results demonstrate that the method is imperceptible and robust for different image processing attacks.