Perceptual watermarks for digital images and video

Abstract

The growth of new imaging technologies has created a need for techniques that can be used for copyright protection of digital images. Copyright protection involves the authentication of image content and/or ownership and can be used to identify illegal copies of a (possibly forged) image. One approach for copyright protection is to introduce an invisible signal known as a digital watermark in the image.In this paper, we describe digital image watermarking techniques, known as perceptually based watermarks, that are designed to exploit aspects of the human visual system. In the most general sense, any watermarking technique that attempts to incorporate an invisible mark into an image is perceptually based. However, in order to provide transparency (invisibility of the watermark) and robustness to attack, more sophisticated use of perceptual information in the watermarking process is required. Several techniques have been introduced that incorporate a simple visual model in the marking procedure. Such techniques usually take advantage of frequency selectivity and weighing to provide some perceptual criteria in the watermarking process. Even more elaborate visual models are used to develop schemes that not only take advantage of frequency characteristics but also adapt to the local image characteristics, providing extremely robust as well as transparent schemes. We present examples from each category -from the simple schemes that guarantee transparency to the more elaborate schemes that use visual models to provide robustness as well as transparency.3

A Probabilistic Dissimilarity Matching for the DFT-Domain Image Hashing

“…However; it is intricate to determine the distortion bound. This paper assumes that the distortion bound is proportional to the value of the magnitude of the transform coefficient itself, as is commonly assumed in transform-domain watermark hiding [10][11][12]. In the case of the polar Fourier-transform hashing, the distortion bound δ Q [j] corresponding to the intermediate hash H Q [j] of the query Q in (1) is given by…”

Survey on Classification of Different Video Watermarking Techniques

“…Wolfgang et. al [29] proposed an image adaptive DCT-based (IA-DCT) method that employed the visual model depicted in [30]. This method comprises an image-independent part related to frequency sensitivity as well as an image-dependent part related to luminance sensitivity, along with contrast masking.…”

Avoiding Hard Decisions in Adaptive Watermarking

“…In recent years, several image watermarking methods have been proposed that adjust the embedding strength depending on the host signal [1]. More sophisticated approaches employ models of the human visual system to keep embedding induced distortions below a just noticeable difference threshold [2].…”