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Oscar C. Au

Bio: Oscar C. Au is an academic researcher from Hong Kong University of Science and Technology. The author has contributed to research in topics: Motion estimation & Motion compensation. The author has an hindex of 40, co-authored 491 publications receiving 7493 citations. Previous affiliations of Oscar C. Au include Wilmington University & Huawei.


Papers
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01 Jan 2000
TL;DR: An algorithm for faster Fractal image coding than traditional algorithms that involves a method of transforming the image from a multibit to a one-bit/pixel representation, applying full search block based estimation on the new image and then refining the result with the use of statistical normalization and fast block-based motion estimation techniques for MPEG encoding.
Abstract: In this paper we present an algorithm for faster Fractal image coding than traditional algorithms. The algorithm involves a method of transforming the image from a multibit to a one-bit/pixel representation, applying MPEG like full search block based estimation on the new image and then refining the result with the use of statistical normalization and fast block-based motion estimation techniques for MPEG encoding. Simulation results suggest that the algorithm can significantly reduce the computation compared to traditional methods.
Proceedings ArticleDOI
19 Jul 2010
TL;DR: A novel segmentation scheme based on recursive SST in the warped domain produced by density estimation is proposed, which is robust for variant natural image input and is easy to implement.
Abstract: In this paper we give a step-by-step detailed analysis on the performance of shortest spanning tree (SST) and its revised version, recursive SST (RSST). We further propose a novel segmentation scheme based on recursive SST in the warped domain produced by density estimation. The proposed method is robust for variant natural image input and is easy to implement. Experimental results and comparisons with other methods have illustrated the effectiveness and robustness of the proposed method.
Proceedings ArticleDOI
11 Jul 2011
TL;DR: This paper analyzes the existence of equivalent operations in the encrypted domain for four of the common bitwise operations: OR, AND, NOR and NAND in plaintext domain and shows that such equivalent operations should not exist.
Abstract: When encrypted data need to be sent to an untrusted computer for processing, it is highly desirable to have a homomorphic cryptosystem that allows the untrusted computer to process the encrypted signals totally without decryption such that, when the encrypted domain result is decrypted, the decrypted value is the same as the equivalent plaintext domain operation. These operations range from basic arithmetic operations to complicated transformations. In this paper, we analyze the existence of equivalent operations in the encrypted domain for four of the common bitwise operations: OR, AND, NOR and NAND in plaintext domain. We will show that such equivalent operations should not exist. For otherwise, if such operations exist, the RSA cryptosystems can be broken by a low-complexity attack.

Cited by
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Journal ArticleDOI

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08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Book
24 Oct 2001
TL;DR: Digital Watermarking covers the crucial research findings in the field and explains the principles underlying digital watermarking technologies, describes the requirements that have given rise to them, and discusses the diverse ends to which these technologies are being applied.
Abstract: Digital watermarking is a key ingredient to copyright protection. It provides a solution to illegal copying of digital material and has many other useful applications such as broadcast monitoring and the recording of electronic transactions. Now, for the first time, there is a book that focuses exclusively on this exciting technology. Digital Watermarking covers the crucial research findings in the field: it explains the principles underlying digital watermarking technologies, describes the requirements that have given rise to them, and discusses the diverse ends to which these technologies are being applied. As a result, additional groundwork is laid for future developments in this field, helping the reader understand and anticipate new approaches and applications.

2,849 citations

Book
23 Nov 2007
TL;DR: This new edition now contains essential information on steganalysis and steganography, and digital watermark embedding is given a complete update with new processes and applications.
Abstract: Digital audio, video, images, and documents are flying through cyberspace to their respective owners. Unfortunately, along the way, individuals may choose to intervene and take this content for themselves. Digital watermarking and steganography technology greatly reduces the instances of this by limiting or eliminating the ability of third parties to decipher the content that he has taken. The many techiniques of digital watermarking (embedding a code) and steganography (hiding information) continue to evolve as applications that necessitate them do the same. The authors of this second edition provide an update on the framework for applying these techniques that they provided researchers and professionals in the first well-received edition. Steganography and steganalysis (the art of detecting hidden information) have been added to a robust treatment of digital watermarking, as many in each field research and deal with the other. New material includes watermarking with side information, QIM, and dirty-paper codes. The revision and inclusion of new material by these influential authors has created a must-own book for anyone in this profession. *This new edition now contains essential information on steganalysis and steganography *New concepts and new applications including QIM introduced *Digital watermark embedding is given a complete update with new processes and applications

1,773 citations

Journal ArticleDOI
TL;DR: This paper provides a state-of-the-art review and analysis of the different existing methods of steganography along with some common standards and guidelines drawn from the literature and some recommendations and advocates for the object-oriented embedding mechanism.

1,572 citations