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Wen-Hsiung Chen

Bio: Wen-Hsiung Chen is an academic researcher. The author has contributed to research in topics: Discrete cosine transform & NTSC. The author has an hindex of 3, co-authored 3 publications receiving 1752 citations.

Papers
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Journal ArticleDOI
TL;DR: A Fast Discrete Cosine Transform algorithm has been developed which provides a factor of six improvement in computational complexity when compared to conventional DiscreteCosine Transform algorithms using the Fast Fourier Transform.
Abstract: A Fast Discrete Cosine Transform algorithm has been developed which provides a factor of six improvement in computational complexity when compared to conventional Discrete Cosine Transform algorithms using the Fast Fourier Transform. The algorithm is derived in the form of matrices and illustrated by a signal-flow graph, which may be readily translated to hardware or software implementations.

1,301 citations

Patent
15 Dec 1978
TL;DR: In this article, a digital video compression and expansion system and its methods for compressing and expanding digitalized video signals in real time at rates up to NTSC color broadcast rates are disclosed.
Abstract: A digital video compression and expansion system and its methods for compressing and expanding digitalized video signals in real time at rates up to NTSC color broadcast rates are disclosed. The system compressor receives digitalized video frames divided into subframes, performs in a single pass a spatial domain to transform domain transformation in two dimensions of the picture elements of each subframe, normalizes the resultant coefficients by a normalization factor having a predetermined compression ratio component and an adaptive rate buffer capacity control feedback component, to provide compression, encodes the coefficients with a minimum redundancy coding scheme and stores them in a first rate buffer memory asynchronously at a high data transfer rate from which they are put out at a slower, synchronous rate. The compressor adaptively determines the rate buffer capacity control feedback component in relation to instantaneous data content of the rate buffer memory in relation to its capacity, and it controls the absolute quantity of data resulting from the normalization step so that the buffer memory is never completely emptied and never completely filled. In expansion, the system essentially mirrors in reverse the steps performed during compression. An efficient, high speed decoder forms an important aspect of the present invention. The compression system forms an important element of a disclosed color broadcast compression system.

390 citations

Patent
20 Apr 1981
TL;DR: In this article, an improved method and apparatus for calculating discrete cosine transform coefficients from a plurality of digitalized data is described, which utilizes two basic types of circuits arranged in five computational stages.
Abstract: An improved method and apparatus for calculating discrete cosine transform coefficients from a plurality of digitalized data is disclosed. The pipelined processor utilizes two basic types of circuits arranged in five computational stages. Shuffle and add circuits operate upon prearranged data components at the first, second and fourth stages, while shuffle, add and multiply circuits are used at the third and fifth stages.

90 citations


Cited by
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Journal ArticleDOI
TL;DR: A near real-time recognition system with 20 complex objects in the database has been developed and a compact representation of object appearance is proposed that is parametrized by pose and illumination.
Abstract: The problem of automatically learning object models for recognition and pose estimation is addressed. In contrast to the traditional approach, the recognition problem is formulated as one of matching appearance rather than shape. The appearance of an object in a two-dimensional image depends on its shape, reflectance properties, pose in the scene, and the illumination conditions. While shape and reflectance are intrinsic properties and constant for a rigid object, pose and illumination vary from scene to scene. A compact representation of object appearance is proposed that is parametrized by pose and illumination. For each object of interest, a large set of images is obtained by automatically varying pose and illumination. This image set is compressed to obtain a low-dimensional subspace, called the eigenspace, in which the object is represented as a manifold. Given an unknown input image, the recognition system projects the image to eigenspace. The object is recognized based on the manifold it lies on. The exact position of the projection on the manifold determines the object's pose in the image. A variety of experiments are conducted using objects with complex appearance characteristics. The performance of the recognition and pose estimation algorithms is studied using over a thousand input images of sample objects. Sensitivity of recognition to the number of eigenspace dimensions and the number of learning samples is analyzed. For the objects used, appearance representation in eigenspaces with less than 20 dimensions produces accurate recognition results with an average pose estimation error of about 1.0 degree. A near real-time recognition system with 20 complex objects in the database has been developed. The paper is concluded with a discussion on various issues related to the proposed learning and recognition methodology.

2,037 citations

Journal ArticleDOI
TL;DR: An efficient general-purpose blind/no-reference image quality assessment (IQA) algorithm using a natural scene statistics model of discrete cosine transform (DCT) coefficients, which requires minimal training and adopts a simple probabilistic model for score prediction.
Abstract: We develop an efficient general-purpose blind/no-reference image quality assessment (IQA) algorithm using a natural scene statistics (NSS) model of discrete cosine transform (DCT) coefficients. The algorithm is computationally appealing, given the availability of platforms optimized for DCT computation. The approach relies on a simple Bayesian inference model to predict image quality scores given certain extracted features. The features are based on an NSS model of the image DCT coefficients. The estimated parameters of the model are utilized to form features that are indicative of perceptual quality. These features are used in a simple Bayesian inference approach to predict quality scores. The resulting algorithm, which we name BLIINDS-II, requires minimal training and adopts a simple probabilistic model for score prediction. Given the extracted features from a test image, the quality score that maximizes the probability of the empirically determined inference model is chosen as the predicted quality score of that image. When tested on the LIVE IQA database, BLIINDS-II is shown to correlate highly with human judgments of quality, at a level that is competitive with the popular SSIM index.

1,484 citations

Patent
08 Sep 1988
TL;DR: A unified programming communication system involving communications of the prior art (such as eg television, radio, print transmitted electronically, and computer communications) and new mass media specific users is defined in this paper.
Abstract: Systeme unifie de communication a programmation regroupant les communications de l'art anterieur (telles que par exemple la television, la radio, l'impression transmise electroniquement, et les communications par ordinateur) ainsi que les nouveaux mass medias specifiques aux utilisateurs. Unified programming communication system involving communications of the prior art (such as eg television, radio, print transmitted electronically, and computer communications) and new mass media specific users. Dans le systeme unifie, des moyens (205) et procedes mettant en oeuvre des systemes d'ordinateurs ont la capacite de produire des informations specifiques a un utilisateur particulier, simultanement a chaque poste (26) d'une pluralite de postes d'abonnes (26). In the unified system, means (205) and methods employing computer systems have the ability to generate specific information to a particular user, simultaneously with each station (26) a plurality of subscriber stations ( 26).

1,164 citations

Patent
03 Jan 1992
TL;DR: In this paper, a system of distributing video and audio information employs digital signal processing to achieve high rates of data compression, and the compressed and encoded audio and video information is sent over standard telephone, cable or satellite broadcast channels to a receiver specified by a subscriber of the service, preferably in less than real time, for later playback and optional recording on standard audio and/or video tape.
Abstract: A system of distributing video and/or audio information employs digital signal processing to achieve high rates of data compression. The compressed and encoded audio and/or video information is sent over standard telephone, cable or satellite broadcast channels to a receiver specified by a subscriber of the service, preferably in less than real time, for later playback and optional recording on standard audio and/or video tape.

1,032 citations

Journal ArticleDOI
TL;DR: The MorphoSys architecture is described, including the reconfigurable processor array, the control processor, and data and configuration memories, and the suitability of MorphoSy for the target application domain is illustrated with examples such as video compression, data encryption and target recognition.
Abstract: This paper introduces MorphoSys, a reconfigurable computing system developed to investigate the effectiveness of combining reconfigurable hardware with general-purpose processors for word-level, computation-intensive applications. MorphoSys is a coarse-grain, integrated, and reconfigurable system-on-chip, targeted at high-throughput and data-parallel applications. It is comprised of a reconfigurable array of processing cells, a modified RISC processor core, and an efficient memory interface unit. This paper describes the MorphoSys architecture, including the reconfigurable processor array, the control processor, and data and configuration memories. The suitability of MorphoSys for the target application domain is then illustrated with examples such as video compression, data encryption and target recognition. Performance evaluation of these applications indicates improvements of up to an order of magnitude (or more) on MorphoSys, in comparison with other systems.

895 citations