• Journal of radiological science and technology
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• v.42 no.4
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• pp.259-263
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• 2019

This study was purpose to compare image quality of Indirect digital radiography (IDR) system by using the International electro-technical commission standard(IEC 62220-1) which were applied to IEC in medical imaging. To evaluation the analysis of Modulation transfer function(MTF) measurements edge device each angle by using edge method. In this study, Aero (Konica, Japan) which is Indirect flat panel detector(FPD) was used, the size of image receptor matrix $1994{\times}2430$ which performed 12bit processing and pixel pitch is $175{\mu}m$. In IEC standard method were applied to each angle were compared. The results of shown as LSF at $2.0^{\circ}$ and $3.0^{\circ}$ angeles. Shape is constant and shows smooth shape. The amount of data seemed reasonable and 2.19 cycles/mm and 2.01 cycles/mm at a spatial frequency of $2.0^{\circ}$ and $3.0^{\circ}$ at an MTF value of 0.1. At an MTF value of 0.5, the spatial frequencies were $2.0^{\circ}$ and 1.11 cycles/mm and 0.93 cycles/mm at an angle of $3.0^{\circ}$. This study were to evaluate MTF by setting the each $2{\sim}3^{\circ}$ each angle and to suggest the quantitative methods of measuring by using IEC.

• Progress in Medical Physics
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• v.21 no.3
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• pp.239-245
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• 2010

The purpose of this study is to comprehensively compare and evaluate the characteristics of image quality for digital mammography systems which use a direct and indirect conversion detector. Three key metrics of image quality were evaluated for the direct and indirect conversion detector, the modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE), which describe the resolution, noise, and signal to noise performance, respectively. DQE was calculated by using a edge phantom for MTF determination according to IEC 62220-1-2 regulation. The contrast to noise ratio (CNR) was evaluated according to guidelines offered by the Korean Institute for Accreditation of Medical Image (KIAMI). As a result, the higher MTF and DQE was measured with direct conversion detector compared to indirect conversion detector all over spatial frequency. When the average glandular dose (AGD) was the same, direct conversion detector showed higher CNR value. The direct conversion detector which has higher DQE value all over spatial frequency would provide the potential benefits for both improved image quality and lower patient dose in digital mammography system.

• Phonetics and Speech Sciences
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• v.1 no.4
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• pp.111-117
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• 2009

In this paper, a new speech endpoint detector in noisy environment is proposed. According to the previous research, the energy feature in the speech region is easily distinguished from that in the speech absent region. In conventional method, the endpoint can be found by applying the edge detection filter that finds the abrupt changing point in feature domain. However, since the frame energy feature is unstable in noisy environment, the accurate edge detection is not possible. Therefore, in this paper, the novel feature extraction method based on spectrum envelop pattern is proposed. Then, the edge detection filter is applied to the proposed feature for detection of the endpoint. The experiments are performed in the car noise environment and a substantial improvement was obtained over the conventional method.

• Journal of Sensor Science and Technology
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• v.14 no.3
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• pp.191-197
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• 2005

When fabricating a vision chip, we should consider the noise problem, such as the fixed pattern noise(FPN) due to the process variation. In this paper, we propose an edge-detection circuit based on biological retina using the offset-free column readout circuit to reduce the FPN occurring in the photo-detector. The offset-free column readout circuit consists of one source follower, one capacitor and five transmission gates. As a result, it is simpler and smaller than a general correlated double sampling(CDS) circuit. A vision chip for edge detection has been designed and fabricated using $0.35\;{\mu}m$ 2-poly 4-metal CMOS technology, and its output characteristics have been investigated.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.2
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• pp.217-224
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• 2005

A new roof edge detection method based on multi level scales of wavelet function is proposed in this paper roof edge and its direction are obtained in this new methods at one time. Besides. scale characteristics of detecting roof edge is analyzed. And a few new methods on fingerprint image pre-processing are described. A method segmenting foreground/background of fingerprint images is proposed, in which Prior estimation of direction field is not required any more. A segmentation method based on multi-scale roof edges is implemented. and the valid scale range of the method is defined. too. And the method is used to segment ridges and valleys in fingerprint images simultaneously The exact direction fields made up of the direction of each point in ridges can be obtained when detecting ridges exactly based on the roof edge detector, in comparison with the traditional coarse estimation of direction fields. Obviously. it will establish a solid foundation for the sequent fingerprint identification.

• Journal of the Semiconductor & Display Technology
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• v.22 no.4
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• pp.59-65
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• 2023

Edge detection in image processing and computer vision is one of the most fundamental operations. Canny edge detection algorithm has excellent performance and is currently widely used. However, it is difficult to process the algorithm in real-time because the algorithm is complex. In this study, the equations required in the algorithm were simplified to facilitate hardware implementation, and the calculation speed was increased by using a parallel structure. In particular, the size and management of local buffers were selected in consideration of parallel processing and filter size so that data could be processed without bottlenecks. It was designed in verilog and implemented in FPGA to verify operation and performance.

• Journal of Communications and Networks
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• v.16 no.6
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• pp.639-644
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• 2014

In low-density parity-check (LDPC) coded multiple-input multiple-output (MIMO) communication systems, probabilistic information are exchanged between an LDPC decoder and a MIMO detector. TheMIMO detector has to calculate probabilistic values for each bit which can be very complex. In [1], the authors presented a class of linear block codes named low-density MIMO codes (LDMC) which can reduce the complexity of MIMO detector. However, this code only supports the outer-iterations between the MIMO detector and decoder, but does not support the inner-iterations inside the LDPC decoder. In this paper, a new approach to construct LDMC codes is introduced. The new LDMC codes can be encoded efficiently at the transmitter side and support both of the inner-iterations and outer-iterations at the receiver side. Furthermore they can achieve the design rates and perform very well over MIMO channels.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.11
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• pp.1635-1644
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• 1993

In this paper, we examine the statistical characteristics of edge enhancing filters and their efficacy as preprocessing operator before edge detection. In particular, edge enhancing filters called the Comparison and Selection(CS), Hachimura-kuwahara(HK), and Selective Average(SA) filters are considered. These filters can reduce noise while producing step-type edges, thus seem to be effective for preprocessing noisy images prior to applying edge detecors. The ability of edge enhancing filters to suppress white Gaussian noise and the error probabilities occured during the edge detection following SA prefiltering are evaluated statistically through numerical analysis. The effect of prefiltering on edge detection is assessed by applying the edge enhancing fitters to a noise image degraded by additive white noise prior to applying the Sobel operator and the Laplacian of Gaussian( LoG ) operator, respectively. It is shown that the edge enhancing filters tend to produce ideal step-type edges while reducing the noise reasonably well, and the use of edge enhancing filters prior to edge detection can improve the performance of subsequent edge detector.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.39 no.1
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• pp.16-21
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• 2002

In this paper, a dual type PFD(Phase Frequency Detector) for high speed PLL to improve output characteristics using TSPC(True Single Phase Clocking) circuit is proposed. The conventional 3-state PFD has problems with large dead-zone and long delay time. Therefore, it is not applicable to high-speed PLL(Phase-Locked Loop). A dynamic PFD with dynamic CMOS logic circuit is proposed to improve these problems. But, it has the disadvantage of jitter noise due to the variation of the duty cycle. In order to solve the problems of previous PFD, the proposed PFD improves not only the dead zone and duty cycle but also jitter noise and response characteristics by the TSPC circuit and dual structured PFD circuit. The PFD is consists of a P-PFD(Positive edge triggered PFD) and a N-PFD(Negative edge triggered PFD) and improves response characteristics to increase PFD gain. The Hspice simulation is performed to evaluate the performance of proposed PFD. From the experimental results, it has the better dead zone, duty cycle and response characteristics than conventional PFDs.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.12
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• pp.2785-2791
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• 2015

In this paper, neddle detection algorithm for the removal of needle stuck into skin in oriental clinic is presented. First, in the proposed method, potential candidate areas of each needle are selected by using the morphological open operation in a gray image, and the false candidates are removed by considering their area size. Next, edge points are extracted using canny edge detector in selected candidate areas, line segments are approximated using the edge points. Based on the direction of line segment and the distance between two line segments, two main line segments of the needle are extracted. The final verification of needle is accomplished by using the morphological analysis of these two line segments. In the experiments, the detection rate of proposed method reaches to 97.5% for the 16 images containing 119 needles.