Abstract
During the last few decades, there has been a rapid growth of digital multimedia due to the development of internet technologies and applications. In order to prevent some illegal users who may easily download and copy digital multimedia data without permission, digital watermarking has gathered great importance in the area of copyright protection and owner identification in recent years. Discrete wavelet transform (DWT) has been widely used for digital watermarking due to its excellent multi-resolution analysis and spatial-frequency localization. Thus, the purpose of this thesis attempts to study the relationship between digital watermarking and DWT. This thesis proposes a watermarking scheme that embeds watermarks into the wavelet coefficients of high-low (HL) and low-high (LH) frequency bands of 2-scale and 3-scale wavelet transforms to investigate their effects on robustness and transparency. The experiments of this thesis involves “5/3” and “9/7” wavelet transforms to examine the effects of our watermarking scheme, and the experimental results show that our watermarking scheme satisfies robustness and transparency after a variety of attacks including scaling, smoothing, noise adding, median filtering, JPEG compression, and cropping. In conclusion, the experimental results of this thesis show a distinct effect of using different kinds of wavelet transforms on performance in our watermarking scheme, we are hopeful that this thesis will contribute to a better understanding of the relationship between digital watermarking and DWT.