Combining Haar Wavelet and Karhunen-Loeve Transform for Robust and Imperceptible Data Hiding Using Digital Images

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 (DWT) 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.