Browsing by Author "Hang, HM"

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A comparison of block-matching algorithms for VLSI implementation
(1996)
Cheng, SC
;
Hang, HM
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A comparison of block-matching algorithms mapped to systolic-array implementation
(1997-10-01)
Cheng, SC
;
Hang, HM
;
電子工程學系及電子研究所
;
電信研究中心
;
Department of Electronics Engineering and Institute of Electronics
This paper presents an evaluation of several well-known block-matching motion estimation algorithms from a system-level very large scale integration (VLSI) design viewpoint, Because a straightforward block-matching algorithm (BMA) demands a very large amount of computing power, many fast algorithms have been developed, However, these fast algorithms are often designed to merely reduce arithmetic operations without considering their overall performance in VLSI implementation, In this paper, three criteria are used to compare various block-matching algorithms: 1) silicon area, 2) input/output requirement, and 3) image quality. A basic systolic array architecture is chosen to implement all the selected algorithms, The purpose of this study is to compare these representative BMA's using the aforementioned criteria. The advantages/disadvantages of these algorithms in terms of their hardware tradeoff are discussed. The methodology and results presented here provide useful guidelines to system designers in selecting a BMA for VLSI implementation.
A feature-based robust digital image watermarking scheme
(2003-04-01)
Tang, CW
;
Hang, HM
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A robust digital image watermarking scheme that combines image feature extraction and image normalization is proposed. The goal is to resist both geometric distortion and signal processing attacks. We adopt a feature extraction method called Mexican Hat wavelet scale interaction. The extracted feature points can survive a variety of attacks and be used as reference points for both watermark embedding and detection. The normalized image of an image (object) is nearly invariant with respect to rotations. As a result, the watermark detection task can be much simplified when it is applied to the normalized image. However, because image normalization is sensitive to image local variation, we apply image normalization to nonoverlapped image disks separately. The disks are centered at the extracted feature points. Several copies of a 16-bit watermark sequence are embedded in the original image to improve the robustness of watermarks. Simulation results show that our scheme can survive low-quality JPEG compression, color reduction, sharpening, Gaussian filtering, median filtering, row or column removal, shearing, rotation, local warping, cropping, and linear geometric transformations.
A low complexity prioritized bit-plane coding for SNR scalability in MPEG-21 scalable video coding
(2005)
Peng, WH
;
Chiang, TH
;
Hang, HM
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this paper, we propose a low complexity prioritized bit-plane coding scheme to improve the rate-distortion performance of cyclical block coding in MPEG-21 scalable video coding. Specifically, we use a block priority assignment algorithm to firstly transmit the symbols and the blocks with potentially better rate-distortion performance. Different blocks are allowed to be coded unequally in a coding cycle. To avoid transmitting priority overhead, the encoder and the decoder refer to the same context to assign priority. Furthermore, to reduce the complexity, the priority assignment is done by a look-up-table and the coding of each block is controlled by a simple threshold comparison mechanism. Experimental results show that our prioritized bit-plane coding scheme can offer up to 0.5dB PSNR improvement over the cyclical block coding described in the joint scalable verification model (JSVM).
A novel approach for edge orientation determination based on pixel pair matching
(1998)
Ting, HC
;
Hang, HM
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A novel edge orientation determination algorithm is proposed. It can detect edges and decide very precisely their orientations based on a pixel pair matching technique. Three image edge structure measures, profile diversity, edge convexity and edge continuity, are designed to facilitate the determination process. The basic algorithm outputs an integer-pixel orientation vector for each detected edge and this orientation vector can be refined to subpixel accuracy by a polynomial fitting method. Simulation results are included to show the advantages of this approach.
A preliminary report on the Phase-I ATSC field test results in Taiwan
(2000)
Tsai, JF
;
Lin, CC
;
Hang, HM
;
Tarng, JH
;
Yu, HC
In May 1998, Taiwan formally adopted the ATSC Digital Television (DTV) as its local digital terrestrial broadcasting standard. In order to define the DTV service area and specify the transmission parameters, we like to know the characteristics of the DTV signal over the local irregular terrain, the impact of interference, and the relationship between the signal power and video quality. me measured the DTV signal and compared the DTV and the NTSC service availability. We selected 100 test sites in Taipei city and its vicinity including three types of environment: urban, suburban and rural areas. In general, the DTV system has a clear advantage over the NTSC system in reception quality.
A relevance feedback image retrieval scheme using multi-instance and pseudo image concepts
(2005)
Chang, FC
;
Hang, HM
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Content-based image search has long been considered a difficult task. Making correct conjectures on the user intention (perception) based on the query images is a critical step in the content-based search. One key concept in this paper is how we find the user preferred image characteristics from the multiple positive samples provided by the user. The second key concept is that when the user does not provide a sufficient number of samples, how we generate a set of consistent "pseudo images". The notion of image feature stability is thus introduced. The third key concept is how we use negative images as pruning criterion. In realizing the preceding concepts, an image search scheme is developed using the weighted low-level image features. At the end, quantitative simulation results are used to show the effectiveness of these concepts.
A robust transform image coder over noisy channel
(1998)
Su, CH
;
Hang, HM
;
Wei, CH
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this paper, we propose a robust quantizer design for image coding. Because the bits representing the reconstruction levels are transmitted directly to the channel, the proposed quantizer can be viewed as a compound of a quantizer, a VLC coder, and a channel coder. The conventional combined source/channel design produces a source coder designed for a channel with a specific channel noise. Our proposed quantizer is designed within a noise range. In comparison with the ordinary JPEG coder, simulation results show that our proposed scheme has a much more graceful distortion behavior within the designed noise range.
A study of alternative broadcasting technologies for the extension of DTV coverage in Taiwan
(2000-12-01)
Yu, HC
;
Tarng, JH
;
Hang, HM
;
Lee, ZY
;
電子工程學系及電子研究所
In Taiwan. there are six major NTSC terrestrial broadcasting stations and 129 relay stations, which cover about 98% of Taiwan's population. This paper addresses the planning of DTV broadcasting in Taiwan. DTV signals will be broadcast from the same six major transmitting sites and are expected to provide similar coverage. To extend DTV coverage beyond the major transmitting sites, only the existing 9 NTSC relay stations with over 100W transmitting power would relay DTV signals. Residences living beyond the above coverage areas could rely on CATV or DTH to receive terrestrial DTV programs.
A video coding algorithm based on image warping and nonrectangular DCT coding
(1997)
Chou, YM
;
Hang, HM
;
交大名義發表
;
電子工程學系及電子研究所
;
National Chiao Tung University
Object scalability is a new trend in video coding research. This paper presents an attempt of designing an object-oriented coding based on the notion of irregular mesh and image warping. Three techniques are employed: motion compensation based on image warping, image segmentation and object tracking based on (mesh) nodal point adjustment, and nonrectangular DCT coding performed on the irregular mesh. The preliminary simulation results of the PSNR values and the subjective coded image quality indicate that this coding scheme is suitable for object scalable coding at low bit rates.
Adaptive piecewise linear bits estimation model for MPEG based video coding
(1995)
Cheng, JB
;
Hang, HM
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Adaptive piecewise linear bits estimation model for MPEG based video coding
(1997-03-01)
Cheng, JB
;
Hang, HM
;
交大名義發表
;
電子工程學系及電子研究所
;
National Chiao Tung University
In many video compression applications, it is essential to control precisely the bit rate produced by the encoder. One critical element in a bits/buffer control algorithm is the bits model that predicts the number of compressed bits when a certain quantization stepsize is used. In this paper, we propose an adaptive piecewise linear bits estimation model with a tree structure. Each node in the tree is associated with a linear relationship between the compressed bits and the activity measure divided by stepsize. The parameters in this relationship are adjusted by the least mean squares algorithm. The effectiveness of this algorithm is demonstrated by an example of digital VCR application. Simulation results indicate that this bits model has a fast adaptation speed even during scene changes. Compared to the bits model derived from training data based on cluster analysis, the adaptive piecewise linear bits model achieves about the same high performance with a much lower complexity and high self-adaptability. A particular advantage of a rate control scheme employing a bits model over the buffer-feedback rate control such as MPEG2 Test Model 5 is that it can control the bits of every microblock very precisely. (C) 1997 Academic Press.
Advances of MPEG scalable video coding standard
(2005)
Peng, WH
;
Tsai, CY
;
Chiang, TH
;
Hang, HM
;
交大名義發表
To support clients with diverse capabilities, the MPEG committee is defining a novel scalable video coding (SVC) framework that can simultaneously support multiple spatial, temporal and SNR resolutions under the constraints of low complexity and low delay. To fulfill the requirements, two major approaches have been considered as the potential technologies. One is the wavelet-based scheme and the other is the scalable extension of MPEG-4 AVC/H.264. This paper aims to give a brief overview for the latest advances of these technologies.
An adaptive inverse halftoning algorithm
(1997-08-01)
Chen, LM
;
Hang, HM
;
交大名義發表
;
電子工程學系及電子研究所
;
National Chiao Tung University
A class of inverse halftoning algorithms that recovers gray-scale (continuous-tone) images from halftone images is proposed. The basic structure is an optimized linear filter, Then, a properly designed adaptive postprocessor is employed to enhance the recovered image quality. Finally, a multistage space-varying algorithm is developed that uses the basic linear filter structure as before but with spatially adaptive parameters.
An adaptive inverse halftoning algorithm
(1997-08-01)
Chen, LM
;
Hang, HM
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A class of inverse halftoning algorithms that recovers gray-scale (continuous-tone) images from halftone images is proposed. The basic structure is an optimized linear filter, Then, a properly designed adaptive postprocessor is employed to enhance the recovered image quality. Finally, a multistage space-varying algorithm is developed that uses the basic linear filter structure as before but with spatially adaptive parameters.
An image feature based robust digital watermarking scheme
(2002)
Tang, CW
;
Hang, HM
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A novel robust digital image watermarking scheme which combines image feature extraction and image normalization is proposed. The goal is to resist both geometrical and signal processing attacks. We adopt a feature extraction method called Mexican Hat wavelet scale interaction. The extracted feature points can survive various attacks such as common signal processing, JPEG compression, and geometric distortions. Thus, these feature points can be used as reference points for both watermark embedding, and detection. The normalized image of a rotated image (object) is the same as the normalized version of the original image. As a result, the watermark detection task can be much simplified when it is done on the normalized image without referencing to the original image. However, because image normalization is sensitive to image local variation, we apply image normalization to non-overlapped image disks separately. The center of each disk is an extracted feature point. Several copies of one 16-bit watermark sequence are embedded in the original image to improve the robustness of watermarks. Simulation results show that our scheme can survive low quality JPEG compression, color reduction, sharpening, Gaussian filtering, median filtering, printing and scanning process, row or column removal, shearing rotation, scaling, local warping, cropping, and linear transformation.
An image retrieval scheme using multi-instance and pseudo image concepts
(2004)
Chang, FC
;
Hang, HM
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Content-based image search has long been considered a difficult task. Making correct conjectures on the user intention (perception) based on the query images is a critical step in the content-based search. One key concept in this paper is how we find the user preferred image characteristics from the multiple samples provided by the user. The second key concept is that when the user does not provide a sufficient number of samples, how we generate a set of consistent "pseudo images". The notion of image feature stability is thus introduced. In realizing the preceding concepts, an image search scheme is developed using the weighted low-level image features. At the end, quantitative simulation results are used to show the effectiveness of these concepts.
An implementation of a simple DAVIC server using orbix
(1996)
Chang, FC
;
Hang, HM
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
An MPEG-4 IPMPX design and implementation on MPEG-21 test bed
(2005)
Fan, CW
;
Chang, FC
;
Hang, HM
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
With the growing demand for distributing digital media contents, the issues of protecting the rights of digital contents are becoming more and more important. In this paper, we introduce the MPEG-4 IPMPX (Intellectual Property Management and Protection Extension) specifications and design its implementation architecture on the MPEG-21 Multimedia Test Bed. This flexible system is capable of integrating lPMPX tools such as encryption/decryption and digital watermarking into it. The main contributions are (1) we design and integrate a software architecture of the IPMPX system and its APIs into the standard-compliant MPEG-21 Test Bed; (2) the implementation of the IPMPX architecture is close to the original IPMPX concepts and thus provides a good validation of the IPMPX capabilities; (3) we develop an application example on the IEPMPX-enabled MPEG-21 Test Bed to show its powerful functionalities. The IPMP subsystem together with the application example has been completed and described in this paper.
Analysis of ATSC field test results in Taiwan
(2002-03-01)
Lin, CC
;
Chen, CM
;
Tarng, JH
;
Hang, HM
;
Yu, HC
Field tests of the transmission performance of the ATSC DTV system have been conducted in Taiwan. The test results as well as comparisons against the NTSC system performance are reported and analyzed. From the measured results the reception characteristics of the DTV can be deduced and can provide guidelines for television stations to design transmission system, schedule equipment deployment, plan service coverage areas, and improve the reception quality of the digital signal.