Dr. Chai Wah Wu Profile

Dr. Chai Wah Wu

at IBM Thomas J Watson Research Ctr

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Publications (11)

Proceedings Article | 3 February 2014 Paper

A Riesz energy based approach to generating dispersed dot patterns for halftoning applications

Chai Wah Wu, Barry Trager, Kartheek Chandu, Mikel Stanich

Proceedings Volume 9015, 90150Q (2014) https://doi.org/10.1117/12.2036613

KEYWORDS: Binary data, Optimization (mathematics), Computer programming, Einsteinium, Stochastic processes, Visualization, Eye, Halftones, Carbon monoxide, Visual system

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Proceedings Article | 3 February 2014 Paper

Hybrid halftoning using direct multi-bit search (DMS) screen algorithm

Kartheek Chandu, Mikel Stanich, Chai Wah Wu, Barry Trager

Proceedings Volume 9015, 90150P (2014) https://doi.org/10.1117/12.2036607

KEYWORDS: Halftones, Printing, Binary data, Frequency modulation, Amplitude modulation, Fermium, Inkjet technology, Visualization, Image resolution, Image quality

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Proceedings Article | 19 February 2013 Paper

A GPU based implementation of direct multi-bit search (DMS) screen algorithm

Barry Trager, Kartheek Chandu, Chai Wah Wu, Mikel Stanich

Proceedings Volume 8655, 86550Z (2013) https://doi.org/10.1117/12.2002583

KEYWORDS: Halftones, Printing, MATLAB, Binary data, Image processing, Computer architecture, Graphics processing units, Visualization, Image quality, Parallel computing

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Proceedings Article | 4 February 2013 Paper

Direct binary search (DBS) algorithm with constraints

Kartheek Chandu, Mikel Stanich, Chai Wah Wu, Barry Trager

Proceedings Volume 8652, 86520K (2013) https://doi.org/10.1117/12.2002554

KEYWORDS: Printing, Halftones, Binary data, Inkjet technology, Visualization, Visual system, Frequency modulation, Algorithms, Visual process modeling, Fermium

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Proceedings Article | 3 April 2008 Paper

Location dependent heuristics for sensor coverage planning

Dinesh Chandra Verma, Chai Wah Wu, Theodore Brown, Amotz Bar-Noy, Simon Shamoun, Mark Nixon

Proceedings Volume 6981, 69810B (2008) https://doi.org/10.1117/12.783458

KEYWORDS: Sensors, Distortion, Sensor networks, Systems modeling, Defense and security, Computer science, Surveillance, Detection and tracking algorithms, Environmental sensing, Roads

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Proceedings Article | 18 October 2004 Paper

Digital watermarking and steganography via overlays of halftone images

Chai Wah Wu, Gerhard Thompson, Mikel Stanich

Proceedings Volume 5561, (2004) https://doi.org/10.1117/12.562175

KEYWORDS: Digital watermarking, Halftones, Binary data, Diffusion, Feature extraction, Steganography, Data hiding, Image processing, RGB color model, Optimization (mathematics)

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Proceedings Article | 1 August 2001 Paper

Application of invisible image watermarks to produce remotely printed, duplication-resistant, and demonstrably authentic documents

Gordon Braudaway, Frederick Mintzer, John Socolofsky, Charles Tresser, Chai Wu

Proceedings Volume 4314, (2001) https://doi.org/10.1117/12.435418

KEYWORDS: Digital watermarking, Digital imaging, Printing, Image transmission, Internet, Optical character recognition, Oceanography, Image compression, Image encryption, Image quality

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Proceedings Article | 1 August 2001 Paper

Limitations and requirements of content-based multimedia authentication systems

Chai Wu

Proceedings Volume 4314, (2001) https://doi.org/10.1117/12.435404

KEYWORDS: Quantization, Distortion, Multimedia, Error control coding, Image compression, Digital watermarking, Cryptography, Tantalum, Computer security, Image processing

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Recently, a number of authentication schemes have been proposed for multimedia data such as images and sound data. They include both label based systems and semifragile watermarks. The main requirement for such authentication systems is that minor modifications such as lossy compression which do not alter the content of the data preserve the authenticity of the data, whereas modifications which do modify the content render the data not authentic. These schemes can be classified into two main classes depending on the model of image authentication they are based on. One of the purposes of this paper is to look at some of the advantages and disadvantages of these image authentication schemes and their relationship with fundamental limitations of the underlying model of image authentication. In particular, we study feature-based algorithms which generate an authentication tag based on some inherent features in the image such as the location of edges. The main disadvantage of most proposed feature-based algorithms is that similar images generate similar features, and therefore it is possible for a forger to generate dissimilar images that have the same features. On the other hand, the class of hash-based algorithms utilizes a cryptographic hash function or a digital signature scheme to reduce the data and generate an authentication tag. It inherits the security of digital signatures to thwart forgery attacks. The main disadvantage of hash-based algorithms is that the image needs to be modified in order to be made authenticatable. The amount of modification is on the order of the noise the image can tolerate before it is rendered inauthentic. The other purpose of this paper is to propose a multimedia authentication scheme which combines some of the best features of both classes of algorithms. The proposed scheme utilizes cryptographic hash functions and digital signature schemes and the data does not need to be modified in order to be made authenticatable. Several applications including the authentication of images on CD-ROM and handwritten documents will be discussed.

Proceedings Article | 21 December 1999 Paper

Error bounds for error diffusion and other mathematical problems arising in digital halftoning

Roy Adler, Bruce Kitchens, Marco Martens, Arnaldo Nogueira, Charles Tresser, Chai Wu

Proceedings Volume 3963, (1999) https://doi.org/10.1117/12.373426

KEYWORDS: Diffusion, Printing, Digital imaging, Image segmentation, Algorithms, Halftones, Chemical elements, Quality measurement, Image quality, Visual system

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Proceedings Article | 26 May 1999 Paper

3D visualization of the scoliotic spine: longitudinal studies, data acquisition, and radiation dosage constraints

Alan Kalvin, Roy Adler, Joseph Margulies, Charles Tresser, Chai Wu

Proceedings Volume 3658, (1999) https://doi.org/10.1117/12.349436

KEYWORDS: Spine, X-ray computed tomography, X-rays, 3D metrology, Surgery, 3D modeling, Reconstruction algorithms, Data acquisition, Data modeling, 3D image processing

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Proceedings Article | 9 April 1999 Paper

Fragile imperceptible digital watermark with privacy control

Don Coppersmith, Frederick Mintzer, Charles Tresser, Chai Wu, Minerva Yeung

Proceedings Volume 3657, (1999) https://doi.org/10.1117/12.344705

KEYWORDS: Digital watermarking, Video, Cryptography, Image enhancement, Image processing, Transform theory, Data conversion, Video processing, Video compression, Data hiding

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Showing 5 of 11 publications

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