Tai-Chiu Hsung - Academia.edu (original) (raw)

Papers by Tai-Chiu Hsung

Journal of Dentistry, 2021

OBJECTIVES The aim of this in-vitro study was to compare the virtual techniques for registering s... more OBJECTIVES The aim of this in-vitro study was to compare the virtual techniques for registering single-implant position to the physical gold standard using a universal-coordinate system. MATERIALS AND METHODS Thirty dentate maxillary resin models with a dental implant inserted in the incisor region were prepared. On each model, a tooth-supported acrylic stent with a 1 cm X 1 cm x 1 cm cubic-corner (CC) was prepared. The Cartesian x,y,z-coordinate of the implant neck and apex were measured physically by a coordinate-measuring machine (CMM) with reference to this CC and served as the gold-standard. The resin models were scanned by a benchtop scanner (Group BS), cone-beam computed tomography (Group CBCT), and intraoral scanner (Group IOS). Stone casts, poured from open-tray polyether impression of the resin models, were scanned by the benchtop scanner (Group BS-cast). The implant neck and apex coordinates with reference to the CC were measured and the differences in the coordinates (∆x, ∆y, ∆z) and distance r from the gold standard were calculated. The data were analyzed by one-sample t-test and one-way ANOVA/Kruskal-Wallis test with the level of significance set at 0.05. RESULTS The implant neck and apex positions of Group BS were statistically different from that of the CMM, r>0 (p<0.001). Group IOS showed a significant less ∆z and r at the implant neck than Group BS-cast (p=0.006). No significant difference was found in the coordinates and distance at implant apex among Groups BS, CBCT, IOS and BS-cast. CONCLUSIONS The physical measurements could be adopted as the gold standard in assessing the single-implant positions. The IOS was more accurate in registering the single-implant neck positions than scanning of the cast. CLINICAL SIGNIFICANCE A universal-coordinate system defined by the cubic-corner allows comparing the virtual techniques in registering single-implant positions to the physical gold standard.

Proceedings of ISCAS'95 - International Symposium on Circuits and Systems

In this paper, a new discrete Radon transform (DRT) and the inverse transform algorithm are propo... more In this paper, a new discrete Radon transform (DRT) and the inverse transform algorithm are proposed. The proposed DRT preserves most of the important properties of the continuous Radon transform, for instance, the Fourier Slice theorem, convolution property, etc. With the convolution property, the computation of a two-dimensional (2-D) cyclic convolution can be decomposed as a number of one-dimensional (1-D)

The wavelet localization technique was recently applied to the study of region-of-interest (ROI) ... more The wavelet localization technique was recently applied to the study of region-of-interest (ROI) tomography. It achieves a significant saving in the required projections if only a small region of a tomographic image is of interest. In this paper, we first show that with the same sampling scheme, a simple interpolation applied to the samples can give a result at least as good as that using the original wavelet localization approach. It implies that the use of the wavelet transform is not the key to the reduction of the sampling requirement. In fact, the quality of the reconstructed ROI is largely determined by the structure of the sampling scheme. Rather than directly reducing the projection number, the use of the wavelet theory permits a clear understanding of how to achieve a good sampling pattern. Based on an error analysis using the wavelet theory, we further suggest a new sampling scheme such that the number of required projections in each angle is reduced in a multiresolution f...

2006-2007 > Academic research: refereed > Refereed conference pape

PloS one, 2016

Three dimensional analysis of the face is required for the assessment of complex changes followin... more Three dimensional analysis of the face is required for the assessment of complex changes following surgery, pathological conditions and to monitor facial growth. The most suitable method may be "dense surface correspondence". This method utilizes a generic facial mesh and "conformation process" to establish anatomical correspondences between two facial images. The aim of this study was to validate the use of conformed meshes to measure simulated maxillary and mandibular surgical movements. The "simulation" was performed by deforming the actual soft tissues of the participant during image acquisition. The study was conducted on 20 volunteers and used 77 facial landmarks pre-marked over six anatomical regions; left cheek, right cheek, left upper lip, philtrum, right upper lip and chin region. Each volunteer was imaged at rest and after performing 5 different simulated surgical procedures using 3D stereophotogrammetry. The simulated surgical movement was d...

2004 IEEE International Symposium on Circuits and Systems (IEEE Cat. No.04CH37512)

ABSTRACT Recent studies show that multiwavelet methods give consistently better performance over ... more ABSTRACT Recent studies show that multiwavelet methods give consistently better performance over traditional methods, such as denoising. It is because multiwavelet gives better representation by using more than one scaling and wavelet functions which have shorter support while keeping desired properties such as orthogonality and symmetry. However, there are still many burden in applying discrete multiwavelet transforms to scalar signals, especially the prefilter design for higher multiplicity (>2). In this paper, we first suggest a simple and direct prefilter design method for any multiplicity. The resulted prefilter is orthogonal and possess second order approximation power. Then, we investigate the performance of higher multiplicity wavelet with the proposed filter on the application of denoising. Simulation results show that the higher multiplicity wavelets usually give better denoising results.

Proceedings of 1997 IEEE International Symposium on Circuits and Systems. Circuits and Systems in the Information Age ISCAS '97

In this paper, a new algorithm for noise reduction using the wavelet transform is proposed. The n... more In this paper, a new algorithm for noise reduction using the wavelet transform is proposed. The new approach can be viewed as a combination of Mallat and Donoho&amp;amp;amp;#x27;s de-noising methods. Similar to Mallat&amp;amp;amp;#x27;s approach, we estimate the regularity of a signal from the evolution of its wavelet transform coefficients across scales. However, we do not perform maxima detection and processing

1997 IEEE International Conference on Acoustics, Speech, and Signal Processing

The wavelet localization technique was recently applied to the application of Region-of-Interest ... more The wavelet localization technique was recently applied to the application of Region-of-Interest tomography. It achieves a signicant s a ving in the required projections if only a small region of a tomographic image is of interest. In this paper, we rstly show that, with the same sampling requirement, a simple interpolation scheme applied on the samples can give a result at least as good as that achieved by using the wavelet localization approach. It means that we can use a much simple approach t o a c hieve the same performance. Second, we propose a new sampling scheme such that the required projections of each angle are further reduced in a multiresolution form. With this sampling scheme, more than 84% of projections are saved to reconstruct a 32x32 pixels region of a 256x256 pixels image. The signal-to-error ratio of the reconstructed region-of-interest is over 50dB as compare with the case of full projection. Moreover, we also investigate the eect of applying the interlaced sampling scheme on the proposed method. It is seen that a further reduction in the sampling requirement can be achieved although a slight decrease in signal-to-error ratio may result.

ICSP '98. 1998 Fourth International Conference on Signal Processing (Cat. No.98TH8344)

For conventional MPEG-1 video decoding, one of the major sources of noise appearing in the decode... more For conventional MPEG-1 video decoding, one of the major sources of noise appearing in the decoded image sequence is the blocking effect, which is incurred by the quantization errors of the image blocks of the key frames. Recently, the wavelet transform modulus maxima (WTMM) approach was proposed to significantly reduce the blocking effect of the decoded image sequence. This algorithm improves the quality of the decoded image sequence in the sense of signal-to-noise ratio as well as visual quality. Nonetheless, the WTMM deblocking algorithm is an iterative algorithm that requires a long computation time to reconstruct the processed WTMM to obtain the deblocked image. In this paper, another wavelet-based deblocking algorithm is studied. The algorithm has the advantage of the WTMM approach that it can effectively identify the edges and the smooth regions of an image irrespective the discontinuities introduced by the blocking effect. It improves over the WTMM approach in that only a simple inverse wavelet transform is required to reconstruct the processed wavelet coefficients to obtain the deblocked image sequence

Proceedings 7th International Conference on Signal Processing, 2004. Proceedings. ICSP '04. 2004.

ABSTRACT Recent studies show that multiwavelet approaches give consistently better performance ov... more ABSTRACT Recent studies show that multiwavelet approaches give consistently better performance over traditional wavelet approaches in application such as denoising. It is because multiwavelet transform, with appropriate initialization, provides better representation of signals so that their difference from noise can be clearly identified. Traditional multiwavelet denoising only considers multiwavelets of multiplicity 2. In this paper, we first suggest a simple 2nd order orthogonal prefilter design method for multiwavelets of higher multiplicity. Then, we study how to select optimal threshold for each resolution level. Simulation results show that higher multiplicity wavelets usually give better denoising results and the proposed threshold estimator suggests good indication for optimal thresholds.

Proceedings of 1997 IEEE International Symposium on Circuits and Systems. Circuits and Systems in the Information Age ISCAS '97, 1997

l h e discrete periodic Radon transfonn (DPRT), which was proposed recently, has been showii to h... more l h e discrete periodic Radon transfonn (DPRT), which was proposed recently, has been showii to have many useful properties that enable a 2-D signal to be processed by some I-D approaches. hi this paper, the application of the DPRT in image restoration is studied. It is based on the fact that the phase infonnation of an image is preserved when it is transfonned by the DPRT. As the phase infonnation is also not distorted by sonie types of blurring, we can make use of the transfonned phase infonnation of the blurred image to perfonn the restoration. The advantage of using the DPRT is that n e can reduce the original 2-D restoration problem to become some I-D ones, then, we make use of the convolution property of the DPRT to impose further constraints on the restoration process to increase the rate of convergence. The transfonned image is then reconstructed using the inverse DPRT algoritlun. We further propose in this paper a new inverse DPRT algoritlun. The new algorithm collects the redundancy in the previous inverse DPRT algorithm and represents thein by a filtering operation. It is then embedded into the restoration process such that it needs not be actually perfonned. As a result, the proposed approach reduces the iteration time by niore than 50% as compared with the traditional approach to restore an image with the same quality. M.11 Hayes. "The ~r e c o~i~t r u c~i o i i 01' ; I 11irr111d sequence from the plrase 01-its 1;ourier t l-a i i~t k) t n i i '~. I I

2010 International Symposium on Intelligent Signal Processing and Communication Systems, 2010

Advanced motion tracking systems have been generally applied to movie production and digital ente... more Advanced motion tracking systems have been generally applied to movie production and digital entertainment. Due to the successful of Nintendo's Wii game machines, low cost motion tracking solutions are of particularly great demand in the computer gaming industry. In this paper, a low cost optical based motion capture system is proposed. The proposed system makes use of 2 high frame

Proceedings of 2001 International Symposium on Intelligent Multimedia, Video and Speech Processing. ISIMP 2001 (IEEE Cat. No.01EX489), 2001

The problem of restoring an image from its convolution with an unknown blur function is a well-kn... more The problem of restoring an image from its convolution with an unknown blur function is a well-known problem in image processing. Many approaches have been proposed to solve the problem and they have shown to have good performance in identifying the blur function or retrieving the original image. However, in actual implementation, various problems incurred due to the large data

Lecture Notes in Computer Science, 2001

Restoring an image from its convolution with an unknown blur function is a well-known ill-posed p... more Restoring an image from its convolution with an unknown blur function is a well-known ill-posed problem in image processing. The generalized cross validation (GCV) approached was proposed to solved the problem and it has shown to have good performance in ...

Proceedings of 3rd IEEE International Conference on Image Processing

In this paper, we introduce a local deblocking algorithm for JPEG decoded images using the wavele... more In this paper, we introduce a local deblocking algorithm for JPEG decoded images using the wavelet transform modulus maxima (WTMM) representation. Under the WTMM representation, we can characterize the blocking effect as: 1) small modulus maxima at block boundaries over smooth regions; 2) noises or irregular structures near strong edges; 3) corrupted edges across block boundaries. The WTMM representation not

Proceedings of the 1998 IEEE International Conference on Acoustics, Speech and Signal Processing, ICASSP '98 (Cat. No.98CH36181)

Blocking effect is considered as the most disturbing artifact of JPEG decoded images. Many resear... more Blocking effect is considered as the most disturbing artifact of JPEG decoded images. Many researchers have suggested various methods to tackle this problem. Recently, the wavelet transform modulus maxima (WTMM) approach was proposed and gives a significant improvement over the previous methods in terms of signal-to-noise ratio and visual quality. However, the WTMM deblocking algorithm is an iterative algorithm that requires a long computation time to reconstruct the processed WTMM to obtain the deblocked image. In this paper, a new wavelet based algorithm for JPEG image deblocking is proposed. The new algorithm is based on the idea that, besides using the WTMM, the singularity of an image can also be detected by computing the sums of the wavelet coefficients inside the so-called "directional cone of influence" in different scales of the image. The new algorithm has the advantage as the WTMM approach that it can effectively identify the edge and the smooth regions of an image irrespective the discontinuities introduced by the blocking effect. It improves over the WTMM approach in that only a simple inverse wavelet transform is required to reconstruct the processed wavelet coefficients to obtain the deblocked image. As the WTMM approach, the new algorithm gives consistent and significant improvement over the previous methods for JPEG image deblocking.

Proceedings of 2005 IEEE International Workshop on VLSI Design and Video Technology, 2005.

ABSTRACT Resource availability-based admission control schemes usually offer a binary accept or r... more ABSTRACT Resource availability-based admission control schemes usually offer a binary accept or reject decision on an individual video stream to a video streaming proxy server. An acceptance is granted whenever the server can guarantee the availability of resource required to support the stream. Otherwise, it will reject the stream. This is the greedy approach. However, our study has discovered that an acceptance of some streams may jeopardize the capacity of a video streaming proxy server. In other words, a server will have its capacity greatly reduced after accepting the requests of some streams "black sheep". If we are able to screen out such streams in advance, we can maintain server capacity by handling them more carefully. In this paper, we have developed several schemes to facilitate such diversion and have determined their strength and weakness in different scenarios under a multiple server platform. To avoid the laborious screening process, we have employed a heuristic function as an indicator to measure the loading status of the server.

2007 15th International Conference on Digital Signal Processing, 2007

One of the major problems of the discrete multiwavelet transform is its high computational comple... more One of the major problems of the discrete multiwavelet transform is its high computational complexity. It stems from the use of the matrix-based multifilters and the extra pre and postfiltering stages, which are popularly adopted for initializing the input data. Recently, we proposed a generalized structure for the discrete multiwavelet transform (GDMWT). The new structure allows the prefilters to embed

Signal Processing, 2003

The discrete periodic Radon transform (DPRT) was proposed recently. It was shown that DPRT posses... more The discrete periodic Radon transform (DPRT) was proposed recently. It was shown that DPRT possesses many useful properties that are similar to the conventional continuous Radon transform. Using these properties, a 2-D signal can be processed by some 1-D approaches to reduce the computational complexity. However, the non-orthogonal structure of DPRT projections introduces redundant operations that often lower the efficiency

… APSIPA ASC 2009 …, 2009

The discrete multiwavelet transform (DMWT) enables a signal to be analyzed in a multiresolution a... more The discrete multiwavelet transform (DMWT) enables a signal to be analyzed in a multiresolution and multidimensional way. While the generated multiwavelet coefficients are vectors in nature, it has been generally understood that correlation exists between the vector elements. This feature has been adopted particularly in image coding applications to allow efficient design of VQ codebook. For a multiresolution analysis, the multiwavelet coefficients are generated from the multiscaling coefficients of the upper level. In this paper, we show that many multiwavelet systems cannot give correlated multiscaling vector elements, as different from the multiwavelet vector elements. But for those that can give correlated multiscaling vector elements, they can provide much information to assist in identifying the "blank" regions in a noisy signal. A new denoising algorithm is then proposed based on this feature and is particularly useful for sparse source signals.