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ROBUST REFERENCE-WATERMARKING SCHEME USING WAVELET PACKET TRANSFORM AND BIDIAGONAL-SINGULAR VALUE DECOMPOSITION

ROBUST REFERENCE-WATERMARKING SCHEME USING WAVELET PACKET TRANSFORM AND BIDIAGONAL-SINGULAR VALUE DECOMPOSITION ROBUST REFERENCE-WATERMARKING SCHEME USING WAVELET PACKET TRANSFORM AND BIDIAGONAL-SINGULAR VALUE DECOMPOSITION Abstract This paper presents a new robust reference watermarking scheme based on wavelet packet transform (WPT) and bidiagonal singular value decomposition (bSVD) for copy- right protection and authenticity. A small gray scale logo is used as watermark instead of randomly generated Gaussian noise type watermark. A reference watermark is generated by original watermark and the process of embedding is done in…

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Robust Wide Baseline Stereo from Maximally Stable Extremal Regions

Robust Wide Baseline Stereo from Maximally Stable Extremal Regions Robust Wide Baseline Stereo from Maximally Stable Extremal Regions   Abstract The wide-baseline stereo problem, i.e. the problem of establishing correspondences between a pair of images taken from different viewpoints is studied. A new set of image elements that are put into correspondence, the so called extremal regions, is introduced. Extremal regions possess highly desirable properties: the set is closed under 1. continuous (and thus projective) transformation of image coordinates and 2. monotonic transformation…

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A Universal Image Quality Index

A Universal Image Quality Index A Universal Image Quality Index Abstract— We propose a new universal objective image quality index, which is easy to calculate and applicable to various image processing applications. Instead of using traditional error sum- mation methods, the proposed index is designed by modeling any image distortion as a combination of three factors: loss of correlation, luminance distortion, and contrast distortion. Although the new index is mathematically defined and no human visual system model is explicitly employed, our experiments on…

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Visual Cryptography

Visual Cryptography Visual Cryptography   Abstract. In this paper we consider a new type of cryptographic scheme, which can decode concealed images without any cryptographic computations. The scheme is perfectly secure and very easy to implement. We extend it into a visual variant of the k out of n secret shazing problem, in which a dealer provides a transparency to each one of the n users; any k of them ca~ see the image by stacking their trazasparencies, but any k - 1…

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A Dual Interpretation for Direct Binary Search and Its Implications for Tone Reproduction and Texture Quality

A Dual Interpretation for Direct Binary Search and Its Implications for Tone Reproduction and Texture Quality A Dual Interpretation for Direct Binary Search and Its Implications for Tone Reproduction and Texture Quality   Abstract— The direct binary search (DBS) algorithm employs a search heuristic to minimize the mean-squared perceptually filtered error between the halftone and continuous-tone original images. Based on an efficient method for evaluating the effect on mean squared error of trial changes to the halftone image, we show that DBS also…

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Impact of HVS Models on Model-Based Halftoning

Impact of HVS Models on Model-Based Halftoning Impact of HVS Models on Model-Based Halftoning     Abstract— A model for the human visual system (HVS) is an important component of many halftoning algorithms. Using the iterative direct binary search (DBS) algorithm, we compare the halftone texture quality provided by four different HVS models that have been reported in the literature. Choosing one HVS model as the best for DBS, we then develop an approximation to that model which significantly improves computational performance while…

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HALFTONE VISUAL CRYPTOGRAPHY VIA DIRECT BINARY SEARCH

HALFTONE VISUAL CRYPTOGRAPHY VIA DIRECT BINARY SEARCH HALFTONE VISUAL CRYPTOGRAPHY VIA DIRECT BINARY SEARCH   ABSTRACT This paper considers the problem of encoding a secret binary image SI into n shares of meaningful halftone images within the scheme of visual cryptography (VC). Secret pixels en- coded into shares introduce noise to the halftone images. We extend our previous work on halftone visual cryptography [1] and propose a new method that can encode the secret pixels into the shares via the direct binary search…

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Color Extended Visual Cryptography Using Error Diffusion

Color Extended Visual Cryptography Using Error Diffusion Color Extended Visual Cryptography Using Error Diffusion   Abstract— Color visual cryptography (VC) encrypts a color secret message into color halftone image shares. Previous methods in the literature show good results for black and white or gray scale VC schemes, however, they are not sufficient to be applied directly to color shares due to different color structures. Some methods for color visual cryptography are not satisfactory in terms of producing either meaningless shares or meaningful shares…

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Halftoning via Direct Binary Search Using Analytical and Stochastic Printer Models

Halftoning via Direct Binary Search Using Analytical and Stochastic Printer Models Halftoning via Direct Binary Search Using Analytical and Stochastic Printer Models     Abstract— We incorporate models for printer dot interactions within the iterative direct binary search halftoning algorithm. Monochrome electro-photographic printers are considered. Both analytical and stochastic models are studied. In the analytical model it is assumed that the printer can generate a circular spot with constant absorptance at each printer addressable location, whereas the stochastic model is based on microscopic absorptance…

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A Blind and Self-Adaptive Digital Watermarking Based on Wavelet-packet Decomposition

A Blind and Self-Adaptive Digital Watermarking Based on Wavelet-packet Decomposition A Blind and Self-Adaptive Digital Watermarking Based on Wavelet-packet Decomposition   Abstract In this paper, a novel blind digital watermarking algorithm using wavelet-packet decomposition is proposed. Firstly, the original image is transformed into frequency domain with wavelet-packet decomposition by using a key that decides which direction will be further transformed, so that the sub bands where watermark is embedded are determined; Secondly, the binary watermark image with copyright information is scrambled with a…

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