Digital watermarking algorithms based on wavelet transforms provide increased performance and perceptual quality. This thesis proposes two wavelet-based schemes: one robust and one fragile. Robust watermarks should withstand attacks, such as compression, while maintaining the data integrity. The first approach presented is an algorithm which implements image watermarking in the domain of an overcomplete, or redundant, wavelet transform. Alternately, fragile watermarks are intended for use in applications wherein any loss of image quality is not acceptable. In the second approach presented, data embedding in the domain of an integer wavelet transform is considered. An algorithm is proposed that uses a bilevel image coder to compress a chosen bitplane, thereby providing space in which to store a payload while guaranteeing perfect image recovery.

In recent years, there are more and more researches on semi-fragile watermarking scheme which can resist JPEG compression. But, there are few researches focused on the recovery of semi-fragile watermarked image. Therefore, in this paper, we not only present a semi-fragile watermarking scheme which can resist JPEG compression but use the error correction code (Reed-Solomon Code) to recover the area being malicious manipulated. At first, we use the semi-fragile watermarking scheme proposed by Lin and Hsieh to detect the counterfeit under the JPEG compression [9]. Its main effect is to resist JPEG compression and to detect the attacked parts without the need of the original image. And then, we will introduce how we use RS code to recover the attacked parts being detected by the semi-fragile watermarking scheme. We use the scheme ¡§Interleaving¡¨ to spread the local pixels to the global area. Next, we encode to each little image block by RS code. The redundant symbols generated by RS code will be signed to be signature attached with the watermarked image. Finally, the receiver can use semi-fragile watermarking scheme to detect attacked part and use the information of the signature to decode these attacked parts. Additionally, we also discuss how to decrease the load of the signature, thus, it can not significant loading of the watermarked image.

When video transmits over error-prone channels, the fragile property of compressed stream makes it sensitive to bit error. Often even a slight error can make video unable to correctly decode. Therefore, there is a need for a good error control method to solve the problem. This paper presents a novel error detection and concealment strategy along with watermark technique. The proposed watermark-based scheme utilizes two kinds of watermark technique, a fragile watermark is used to detect and localize errors, and a robust watermark is used to reconstruct error areas when errors exist. Experimental results show the proposed watermark-based scheme has good error detection capabilities and complete error recovery information, therefore significant improves video quality after errors happened, especially in the case of higher loss probabilities.

Image and video quality evaluation is very important. In applications involving signal transmission, the Reduced- or No-Reference quality metrics are generally more practical than the Full-Reference metrics. Digital watermarking based quality evaluation emerges as a potential Reduced- or No-Reference quality metric, which estimates signal quality by assessing the degradation of the embedded watermark. Since the watermark contains a small amount of information compared to the cover signal, performing accurate signal quality evaluation is a challenging task. Meanwhile, the watermarking process causes signal quality loss. To address these problems, in this thesis, a framework for image and video quality evaluation is proposed based on semi-fragile and adaptive watermarking. In this framework, adaptive watermark embedding strength is assigned by examining the signal quality degradation characteristics. The "Ideal Mapping Curve" is experimentally generated to relate watermark degradation to signal degradation so that the watermark degradation can be used to estimate the quality of distorted signals. With the proposed framework, a quantization based scheme is first implemented in DWT domain. In this scheme, the adaptive watermark embedding strengths are optimized by iteratively testing the image degradation characteristics under JPEG compression. This iterative process provides high accuracy for quality evaluation. However, it results in relatively high computational complexity. As an improvement, a tree structure based scheme is proposed to assign adaptive watermark embedding strengths by pre-estimating the signal degradation characteristics, which greatly improves the computational efficiency. The SPIHT tree structure and HVS masking are used to guide the watermark embedding, which greatly reduces the signal quality loss caused by watermark embedding. Experimental results show that the tree structure based scheme can evaluate image and video quality with high accuracy in terms of PSNR, wPSNR, JND, SSIM and VIF under JPEG compression, JPEG2000 compression, Gaussian low-pass filtering, Gaussian noise distortion, H.264 compression and packet loss related distortion.

Image and video quality evaluation is very important. In applications involving signal transmission, the Reduced- or No-Reference quality metrics are generally more practical than the Full-Reference metrics. Digital watermarking based quality evaluation emerges as a potential Reduced- or No-Reference quality metric, which estimates signal quality by assessing the degradation of the embedded watermark. Since the watermark contains a small amount of information compared to the cover signal, performing accurate signal quality evaluation is a challenging task. Meanwhile, the watermarking process causes signal quality loss. To address these problems, in this thesis, a framework for image and video quality evaluation is proposed based on semi-fragile and adaptive watermarking. In this framework, adaptive watermark embedding strength is assigned by examining the signal quality degradation characteristics. The "Ideal Mapping Curve" is experimentally generated to relate watermark degradation to signal degradation so that the watermark degradation can be used to estimate the quality of distorted signals. With the proposed framework, a quantization based scheme is first implemented in DWT domain. In this scheme, the adaptive watermark embedding strengths are optimized by iteratively testing the image degradation characteristics under JPEG compression. This iterative process provides high accuracy for quality evaluation. However, it results in relatively high computational complexity. As an improvement, a tree structure based scheme is proposed to assign adaptive watermark embedding strengths by pre-estimating the signal degradation characteristics, which greatly improves the computational efficiency. The SPIHT tree structure and HVS masking are used to guide the watermark embedding, which greatly reduces the signal quality loss caused by watermark embedding. Experimental results show that the tree structure based scheme can evaluate image and video quality with high accuracy in terms of PSNR, wPSNR, JND, SSIM and VIF under JPEG compression, JPEG2000 compression, Gaussian low-pass filtering, Gaussian noise distortion, H.264 compression and packet loss related distortion.

Image and video quality evaluation is very important. In applications involving signal transmission, the Reduced- or No-Reference quality metrics are generally more practical than the Full-Reference metrics. Digital watermarking based quality evaluation emerges as a potential Reduced- or No-Reference quality metric, which estimates signal quality by assessing the degradation of the embedded watermark. Since the watermark contains a small amount of information compared to the cover signal, performing accurate signal quality evaluation is a challenging task. Meanwhile, the watermarking process causes signal quality loss. To address these problems, in this thesis, a framework for image and video quality evaluation is proposed based on semi-fragile and adaptive watermarking. In this framework, adaptive watermark embedding strength is assigned by examining the signal quality degradation characteristics. The "Ideal Mapping Curve" is experimentally generated to relate watermark degradation to signal degradation so that the watermark degradation can be used to estimate the quality of distorted signals. With the proposed framework, a quantization based scheme is first implemented in DWT domain. In this scheme, the adaptive watermark embedding strengths are optimized by iteratively testing the image degradation characteristics under JPEG compression. This iterative process provides high accuracy for quality evaluation. However, it results in relatively high computational complexity. As an improvement, a tree structure based scheme is proposed to assign adaptive watermark embedding strengths by pre-estimating the signal degradation characteristics, which greatly improves the computational efficiency. The SPIHT tree structure and HVS masking are used to guide the watermark embedding, which greatly reduces the signal quality loss caused by watermark embedding. Experimental results show that the tree structure based scheme can evaluate image and video quality with high accuracy in terms of PSNR, wPSNR, JND, SSIM and VIF under JPEG compression, JPEG2000 compression, Gaussian low-pass filtering, Gaussian noise distortion, H.264 compression and packet loss related distortion.