Chau-Wai Wong

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In this paper, we propose a new DCT-like kernel IK(5,7,3) and revitalize another DCT-like kernel IK(13,17,7) for the transform coding process of hybrid video coding. Making use one of these kernels together with the H.264/AVC Kernel IK(1,2,1), we are able to design new multiple-kernel schemes which give better coding performance over that of the(More)
Multiple videos capturing the same scene from possibly different viewing angles may be synthesized for novel immersive experience. Synchronization is an important task for such applications involving multiple pieces of audio-visual data. In this work, we exploit the electric network frequency (ENF) signal inherently embedded in the soundtrack and/or image(More)
Low-cost physically unclonable functions (PUFs) can be deployed with consumer products to deter counterfeiting. An intrinsic physical property - unique textures of paper or other surface - has received strong interest. Extrinsically introduced features, such as randomly positioned bubbles and fiber segments, have also been deployed in the industry to(More)
In a recent paper, Dong et al. proposed a set of order-16 Nonorthogonal Integer Cosine Transforms (NICT’s). They proved that the reconstruction error caused by the nonorthogonality is negligible as compared to the error caused by the quantization. However, we would like to point out three problems found in derivations and also give two comments.(More)
This work studies the paper authentication problem by exploiting optical features through mobile imaging devices to characterize the unique, physically unclonable properties of paper surface. Prior work showing high matching accuracy either used a consumer-level scanner for estimating a projected normal vector field of the surface of the paper as the(More)
Digitally acquired high dynamic range (HDR) video baseband signal can take 10-12 bits per color channel. It is economically important to be able to reuse the legacy 8 or 10-bit video codecs to efficiently compress the HDR video. Linear or nonlinear mapping on the intensity can be applied to the baseband signal to reduce the dynamic range before the signal(More)
In this paper, we present an analysis of the dyadic approximation error introduced by the integerization of transform coding in H.264/AVC-like codecs. We derive the analytical formulations for dyadic approximation error and nonorthogonality error. We further classify the dyadic approximation error into a “system error” and a “nonflat(More)
This paper studies the authentication problem of specific pieces of paper using mobile imaging devices. Prior work showing high matching accuracy has used the <italic>normal vector field</italic>, which serves as a unique, microscopic, physically unclonable feature of paper surfaces, estimated by consumer grade scanners. Industrial cameras were also used to(More)
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