Browsing by Author "Ching, YT"

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A method to extract spots from the image of the ELISA (Enzyme-Linked Immunosorbent Assay) Spot Assay
(2001)
Lin, CY
;
Ching, YT
;
Wu-Hsieh, BA
;
資訊工程學系
;
Department of Computer Science
ELISA (Enzyme-Linked Immunosorbent Assay) Spot Assay is a method widely used by immunologists to enumerate cytokine-producing cells within a specific cell population. The result of ELISA is presented in an image containing numerous color spots. We present a method to extract and to count the number of spots. The proposed method is based on color analysis. Since CIE L(*)u(*)v(*) space have linear perceptibility of color differences, we convert the RGB space to L(*)u(*)v(*) space. The system is trained to obtain the standard color of the spots and get the color difference image in L(*)u(*)v(*) space. According to the feature of the spots we design a special matched filters to filter out the noise and enhance the spots. Finally a binary image is obtained. In the binary images, pixels in the spots have gray scale 255 and the others are 0. Our design makes it easy to analyze the perimeter and size of the spots in addition to counting them in the binary image.
A new antialiased line drawing algorithm
(2001-04-01)
Chen, BC
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Ching, YT
;
資訊工程學系
;
Department of Computer Science
Consider a line f`(x) = mx + b, 0 less than or equal to m less than or equal to 1. Conventional line drawing algorithms sample (x,f(x)) on the line, where x must be an integer, and then map (x,f(x)) to the Frame buffer according to the defined filter and its). In this paper, we propose to simulate a sampled point (x,f(x)) by the four pixels around it where x and f(x) are not necessary to be integers. Based on the proposed low-pass filtering, we show that the effect of sampling at infinite number of points along a line segment can be achieved since the closed Form of the intensities assigned to pixels exists. Furthermore, we show the coherence properties that can reduce the cost for computing these intensities. (C) 2001 Elsevier Science Ltd. All rights reserved.
A note on computing the saddle values in isosurface polygonization
(1997)
Lin, CC
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Ching, YT
;
資訊工程學系
;
Department of Computer Science
The ambiguity problem of the marching cubes method can be solved by constructing isosurfaces that are topologically consistent with the trilinear interpolant. This can be achieved by computing the saddle values of the interpolant. In this note, we analyze the trilinear interpolant and derive an efficient method of computing the saddle values.
A robust image hiding method using wavelet technique
(2006-01-01)
Lin, CY
;
Ching, YT
;
資訊工程學系
;
Department of Computer Science
A robust wavelet-based image hiding methods, that hide still images, E, inside a covered image, C, to establish a composite image, P, are presented. We can hide up to three full-size embedded images inside a cover image while maintaining the quality of the composite image. The embedded images retain easily recognizable when extracted. The embedded images can be extracted fairly completely even when lossy compression or cropping is applied to the composite image. The proposed method does not require the original cover image to extract the embedded image.
A volume rendering algorithm using an analytic approach for curvilinear volumes
(1999-11-01)
Lin, CC
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Ching, YT
;
資訊工程學系
;
Department of Computer Science
A new approach is presented to visualize curvilinear volume data produced using the CFD or FEM Methods. Ray, casting methods are effective and renders images with good quality. However, these methods suffer from a tremendous number of computations and can not deal with the curvilinear volume efficiently. The marching cubes method is a popular approach when the ambiguity problem reduces the reliability of the rendered image. We propose a new method to solve these problems. Our method is a cell-by-cell process which constructs sosurfaces using trilinear functions. Several speed up techniques are proposed to reduce the number of computations in our algorithm. In addition to this, error analysis and error minimization are also discussed. Our method is also easy to implement parallelized.
Almost automatic method for reconstruction 3D geometric model of the left ventricle from 3D+1D precordial echocardiogram
(2001-01-01)
Ching, YT
;
Liu, YH
;
Chang, CL
;
Chen, JSJ
;
資訊工程學系
Echocardiography is the most convenient means for both physicians and patients for heart disease diagnosis. The 3D+1D echocardiogram. provides important information for evaluation of the 3D heart function such as the ejection fraction or wall motion. The most basic task to evaluate such functions of a heart is to segment left ventricles and reconstruct the the 3D geometric model of left ventricle from a set of echocardiographic images. Since there are many images involved, the method should not need too many user assists. In this work, we design a method for reconstructing the left ventricles with very few user assists.
An attempt to build a WEB-based tele-radiology collaborated diagnosis system
(2001-01-01)
Tsao, BS
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Ching, YT
;
Lin, MYY
;
Chen, JSJ
;
Lee, WJ
We present a web-based collaborated diagnosis system developed using Java programming language. The system allows more than two physicians to look at the same images, to discuss through a chat box, and to make diagnosis collaboratively. The system provides tools such as window and value setting that physicians generally need. Beside the tools, we are implementing different tools for the system such as a volume rendering algorithm and an animation playback method. To make the system easily accessed, all the physician need is a web browser.
An automatic method to determine mitral annular lines from 2D+1D precordial echocardiogram
(2000)
Liu, YS
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Ching, YT
;
Chen, SJ
;
資訊工程學系
;
Department of Computer Science
We present a method to determine the sequence of mitral annular lines in 2D + 1D precordial echocardiogram. We first use the optical flow technique a 2-means algorithm to determine a set of possible mitral annular points. A pair of mitral annular points could form the mitral annular line. The problem to determine the sequence of mitral annular lines in 2D + 1D echocardiogram is modeled as a problem to find the shortest path in a graph. The proposed method need very few user inputs. Experimental results show that we can find accurate mitral annular lines.
An efficient volume-rendering algorithm with an analytic approach
(1996)
Lin, CC
;
Ching, YT
;
資訊工程學系
;
Department of Computer Science
We present a new approach, analytic isosurface rendering, for volume rendering. The isosurface of a cell can be modeled as an analytic function, and the intersection between a ray and the isosurface can be computed directly. An octree structure efficiently searches the cells containing isosurfaces. The octree is easy to implement and can be stored in a compact form. It needs extra memory space - at most 27/64 of the size of the original data volume. Front-to-back projection can easily be implemented under the octree structure. A union-find-based algorithm maintains the frame buffer efficiently. Experimental results show that a volume rendering program with our approach is very efficient and maintains the quality of the rendered images.
Cardiac boundary extraction on echocardiographic images using directed graph
(2000-01-01)
Ching, YT
;
Chang, CL
;
資訊工程學系
;
Department of Computer Science
Cardiac boundary extraction on echocardiographic images is essential for quantification of cardiac function. Tracing the endocardial boundaries on the end-diastolic and end-systolic images allows the computation of clinically important measures such as ejection rate. It is a clinical need for automatically detecting the borders. In this paper, we proposed a new approach for cardiac boundary extraction on echocardiographic images by directed graph. In this approach, we spread the cardiac image in the circular direction. The spread image is mapping to a directed graph. The shortest path is found by the dynamic programming algorithm. From the implemented results, we can obtain pretty good approximation for cardiac boundary extraction.
Comparing lanes in the pulsed-field gel electrophoresis (PFGE) images
(2001)
Cheng, WZ
;
Yen, KS
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Lin, CY
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Ching, YT
;
Yang, YL
Pulsed-field Gel Electrophoresis (PFGE) is an important tool in genomic analysis. The result of PFGE is presented in an image. Each image contains several lanes. And each lane consists of bands. Two lanes are identical if the relative positions of bands are the same. We present a method that uses computer to extract the lanes and compare the lanes in the electrophoresis images. The presented method consists of two major steps. The first step is image processing and lane extraction. The second step is to convert a lane into chain code representation. The lane comparison is carried out through calculating the longest common subsequence between lanes. We define the distance between lanes in term of the LCS and the lengths of two lanes. Two lanes have smaller distance tend to have similar pattern. This method eliminates those very different patterns to help biologists reduce the lanes that need to be compared.
Computer method for ELISA spot assay analysis
(2005-08-01)
Lin, CY
;
Ching, YT
;
Wu-Hsieh, BA
;
資訊工程學系
;
Department of Computer Science
The ELISA (enzyme-linked immunosorbent assay) spot assay is a method widely used by immunologists to enumerate cytokine-producing cells within a specific cell population. The ELISA results are presented in an image containing numerous colored spots. We present a method to identify the spots in the image and report on important statistics regarding them. The proposed method employs color analysis in the CIE Luv color space and matched filter technique. The system is trained to obtain a standard color for the spots and calculate the color differences between the spots and background in the Luv space. Matched filters are then used to remove noise and enhance the spots in the color difference map. Intensity thresholding is applied to obtain a binary image in which the pixels in the spots have a grayscale of 1 while the grayscale of the other pixels is 0. A software system is implemented, based on this method, to help immunologists analyze the results obtained from the. ELISA. (c) 2005 Society of Photo-Optical Instrumentation Engineers.
Detecting line segments in an image - a new implementation for Hough Transform
(2001-03-01)
Ching, YT
;
資訊工程學系
;
Department of Computer Science
The conventional Hough Transform is a technique for detecting line segments in an image. The conventional Hough Transform transforms image points into lines in the parameter space. If there are collinear image points, the lines transformed from the points intersect at a point in the parameter space. Determining the intersection is generally carried out through the "voting method", which partitions the parameter space into squared meshes. A problem with the voting method involves determining the resolution required for partitioning the parameter space. Tn this payer. we present a solution to this problem. We propose to transform an image point into a belt, whose width is a function of the width of a line in the image. We then determine the intersection of numerous belts to detect a line segment. An iterated algorithm based the transformation for detecting line segments is presented in this paper. (C) 2001 Elsevier Science B.V. All rights reserved.
Efg1 involved in drug resistance by regulating the expression of ERG3 in Candida albicans
(2005-03-01)
Lo, HJ
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Wang, JS
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Lin, CY
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Chen, CG
;
Hsiao, TY
The ERG3 gene in Candida albicans was identified as a gene whose mRNA level was higher in the cph1/cph1 efg1/efg1 double mutant than in the wild-type cells. Further study showed that Efg1, but not Cph1, negatively regulated ERG3. Mutations in EFG1 consistently increased the susceptibility of the cells to antifungal agents.
Establishing a Web-based DICOM teaching file authoring tool using open-source public software
(2005-09-01)
Lee, WJ
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Yang, CY
;
Liu, KL
;
Liu, HM
;
Ching, YT
Online teaching files are an important source of educational and referential materials in the radiology community. The commonly used Digital Imaging and Communications in Medicine (DICOM) file format of the radiology community is not natively supported by common Web browsers. The ability of the Web server to convert and parse DICOM is important when the DICOM-converting tools are not available. In this paper, we describe our approach to develop a Web-based teaching file authoring tool. Our server is built using Apache Web server running on FreeBSD operating system. The dynamic page content is produced by Hypertext Preprocessor (PHP). Digital Imaging and Communications in Medicine images are converted by ImageMagick into Joint Photographic Experts Group (JPEG) format. Digital Imaging and Communications in Medicine attributes are parsed by dicom3tools and stored in PostgreSQL database. Using free software available from the Internet, we build a Web service that allows radiologists to create their own online teaching file cases with a common Web browser.
Extraction of coronary arteries by using a sequence of x-ray angiographic images
(2001-01-01)
Lin, CY
;
Ching, YT
;
Chen, SYJ
;
資訊工程學系
;
Department of Computer Science
A method was developed for extraction coronary arteries from a contiguous sequence of angiographic images. Since coronary artery in the image usually has poor local contrast and has ribs, spine, and other tissues in the background. We remove the background using the information of temporal continuity. A set of multi-size matched filters process to enhance vessels from poor local contrast. The wavelet transformation based method is then employed to remove noise to enhance the image quality. We also design a stencil mask to remove the stationary tissues further.
Finding the mitral annular lines from 2-D+1-D precordial echocardiogram using graph-search technique
(2004-03-01)
Ching, YT
;
Chen, SJ
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Chang, CL
;
Lin, CY
;
Liu, YH
The apical four-chamber view echocardiogram collected by a transthoracic transducer can be used to evaluate the left ventricle volume. In the diastole, the left ventricle and left atrium become one chamber. In this case, the left ventricle and left atrium need to be separated using a "mitral annular line" so the volume of the left ventricle can be estimated. In this paper, a nearly automatic method for identifying the mitral annular lines from two-dimensional (2-D) + one-dimensional (1-D) precordial four-chamber view echocardiogram is presented. This method employs the optical flow technique and graph-search approach. The mitral annular line sequence is found by finding the shortest path in a weighted directed graph. The vertices in the graph are candidates for the mitral annular lines. The weights on the directed edges are determined using the optical flow technique. The proposed method requires only a physician to provide, a point that is always in the left ventricular chamber. Experimental results show that the average error for the left ventricle volume obtained based on the computed mitral annular lines is 3%.
Fuzzy Hopfield neural network with fixed weight for medical image segmentation
(2002-02-01)
Chang, CL
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Ching, YT
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資訊工程學系
;
Department of Computer Science
Image segmentation is a process for dividing a given image into meaningful regions with homogeneous properties. A new two step approach is proposed for medical image segmentation using a fuzzy Hopfield neural network based on both global and local gray-level information. The membership function simulated with neuron outputs is determined using a fuzzy set, and the synaptic connection weights between the neurons are predetermined and fixed to improve the efficiency of the neural network. The proposed method needs initial cluster centers. The initial centers can be obtained from the global information about the distribution of the intensities in the image, or from prior knowledge of the intensity of the region of interest. It is shown by experiments that the proposed fuzzy Hopfield neural network approach is better than most previous approaches. We also show that the global information can be used by applying the hard c-means to estimate the initial cluster centers. (C) 2002 Society of Photo-Optical Instrumentation Engineers.
Identify the centerline of tubular structure in medical images
(2005)
Ching, YT
;
Yeh, C
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資訊工程學系
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Department of Computer Science
Finding the centerline of the tubular structure helps to segment or analyze the organs such as the vessels or neuron fibers in medical images. This paper described a semi-automatic method using the minimum cost path finding and Hessian matrix analysis in scale space to calculate the centerline of tubular structure organs. Unlike previous approaches, exhaustive search for tine-like shapes in every scale is prevent. Centerline pixels candidates and the width of the vessel are extracted by analyzing the intensity profile along the gradient vectors in the image. A verification procedure using Hassian matrix analysis with the scale obtained from the gradient analysis is applied to those candidates. Results obtained from the Hessian matrix analysis are used to construct a weighted graph. Finding the minimum cost path in the graph gives the centerline of the tubular structure. The method is applied to find the centerline of the vessels in the 2D angiogram and the neuron fibers in the 3D confocal microscopic images.
Reconstruction of 3D geometric models of pulmonary arteries from cardiac CT images
(2002)
Yu, CC
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Ching, YT
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Chen, SJ
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資訊工程學系
;
Department of Computer Science
We present a method to construct the geometric model of the pulmonary arteries from a set of cardiac CT scan images. It is desired that the model is in rectangular meshes. The main difficulties in this work are insufficient resolution along z-direction, the requirement of the rectangular meshes, and the geometric shape of the pulmonary arteries. We present a method that is based on estimation the medial axis and the radii of the vessel along the axis. We evaluate the proposed method using a phantom data set. The proposed method can achieve good reconstructed result for the phantom data set.