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Feature extraction from retinal fundus image for early detection of diabetic retinopathy
(2013-12-01)
Sreng, Syna
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Takada, Jun Ichi
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Maneerat, Noppadol
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Isarakorn, Don
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Varakulsiripunth, Ruttikorn
Automated detection of lesions in retinal fundus image can be aid in the detection of diabetic retinopathy. Exudates are the early sign of diabetic retinopathy so the proper detection of these lesions is an essential task in an automatic retinal screening. On the research work leading to automatic analysis of exudate detection, the knowledge of Optic Disk (OD) location is very useful. An efficient algorithm is presented to detect the OD and exudate which are the most important features for early detection of diabetic retinopathy. From a retinal fundus image, the proposed method first preprocesses and estimates the histogram of retinal background, then filters out the bright pixels in intensity image. They include OD, and non-OD (exudates and noise). Next, an OD boundary is determined and eliminated after applying blob boundary measurement and morphological reconstruction. Finally, exudates are extracted by applying the maximum entropy thresholding to filter out the bright pixels from the green component of retinal image which OD region inside is eliminated. The proposed technique has been tested first on 100 images from hospital. Experimental results show that 93% and 89% of OD and exudate were detected correctly, respectively. © 2013 IEEE.
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Automatic exudate extraction for early detection of Diabetic Retinopathy
(2013-01-01)
Sreng, Syna
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Takada, Jun Ichi
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Maneerat, Noppadol
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Isarakorn, Don
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Pasaya, Bundit
Diabetic Retinopathy (DR) is the most common cause of blindness in diabetic patients, but early detection and timely treatment can prevent this problem. Exudates have been found to be one of the signs and serious DR anomalies so the proper detection of these lesions and the treatment should be done immediately to prevent loss of vision. The aim of this study is to automatically detect these lesions in fundus images. To achieve this goal, the proposed method first preprocesses to improve the quality of fundus image, and then Optic Disc (OD) is detected and eliminated to prevent the interference to the result of exudate detection by combination of 3 methods; image binarization, Region Of Interest (ROI) based segmentation and Morphological Reconstruction (MR). Next, exudates are detected by applying the maximum entropy thresholding to filter out the bright pixels from the result of OD region eliminated. Since the result contains some noises which appear as bright light at the edge of fundus area in some images, that affect is considered and eliminated to improve the result of false positive. Finally, exudates are extracted by using MR. The proposed technique has been tested on 100 fundus images from hospital. Experimental results show that 91 % of exudate is extracted correctly with the average process of 3.92 second per image. © 2013 IEEE.
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Comprehensive characterization of a novel UWB elliptical planar monopole antenna
(2012-12-01)
Marindra, Adi Mahmud Jaya
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Promwong, Sathaporn
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Takada, Jun Ichi
The rise of research in ultra wideband (UWB) antenna design must be followed by a proper method of antenna characterization. The emerging concept of UWB impulse radio (UWB-IR) compels the performance evaluation of UWB antenna should be assessed in different ways from narrowband antennas. In this paper, a comprehensive characterization of UWB antenna will be discussed. Based on the theory of antenna transfer function in frequency domain, some UWB transmission parameters in time domain are derived, i.e. waveform correlation, waveform width stretch ratio, and waveform relative gain. For practical testing, we propose a novel UWB elliptical planar monopole antenna as the characterized antenna. The results show that the overall performance and characteristic of the proposed antenna is very good, especially at the antenna boresight. The derived parameters can quantitatively characterize the UWB antenna for all the measured directions so that the detail of transmission performance of the UWB antenna could be known. Hopefully, the characterization scheme with the proposed antenna presented in this paper provide useful insight either for UWB antenna design or for evaluating UWB antenna performance. © 2012 IEEE.
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Performance evaluation of ultra wideband printed antenna by system characterization
(2012-10-02)
Marindra, Adi Mahmud Jaya
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Promwong, Sathaporn
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Takada, Jun Ichi
A lot of Ultra Wideband (UWB) antenna designs, especially printed antenna, have been proposed so far. However, among those proposed designs, only single unit antenna analysis i.e. return loss and radiation pattern at particular frequencies are usually observed. This paper reports a deeper transmission analysis by considering UWB antenna as a system; so called system characterization. For a specific case, a pair of UWB printed monopole antenna with known single unit antenna performance was used for this study. Two-identical-antenna system was measured with Vector Network Analyzer (VNA), then its system transfer function, group delay, and waveform distortion are investigated. The results show that even the single unit antenna performance looks good enough but not so that well when the antenna is considered as a system. Nonlinear transfer function and group delay at some frequency ranges inflicts distortion in the waveform transmission which is crucial for UWB impulse radio scheme. Antenna performance evaluation in this study is provided in the term of its distortion by showing pattern of correlation between the transmitted and the received waveform. © 2012 IEEE.
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Location fingerprint technique using Fuzzy C-Means clustering algorithm for indoor localization
(2011-12-01)
Suroso, Dwi Joko
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Cherntanomwong, Panarat
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Sooraksa, Pitikhate
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Takada, Jun Ichi
The recent researches in localization technique have been supported by the emerging of wireless sensor network (WSN) technology. The issues of power and time consumption have become the main research topics in WSN-based localization technique. ZigBee as IEEE 802.15.4 is commonly used as supporting device because of its advantages for low-power, small and smart sensor nodes. This paper proposes the new technique in radio frequency (RF) fingerprint technique-based localization using Fuzzy C-Means (FCM) clustering algorithm. This technique provides an efficient localization system that gives benefit in the time-efficient and low power consumption. In this paper, received signal strength indicator (RSSI) is used as the fingerprint information which indicates the location of sensor nodes. The different amount of the reference nodes is applied. The effectiveness of this method is verified by an indoor experiment. The estimated location results from different sets of reference nodes are compared. The time consumption in experiment is compared with those using the common fingerprint technique. © 2011 IEEE.
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Fingerprint-based technique for indoor localization in wireless sensor networks using Fuzzy C-Means clustering algorithm
(2011-12-01)
Suroso, Dwi Joko
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Cherntanomwong, Panarat
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Sooraksa, Pitikhate
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Takada, Jun Ichi
ZigBee as IEEE 802.15.4 standard has been using for main research topic in the wireless sensor network (WSN) applications. The new method of radio frequency (RF) fingerprint-based technique for indoor localization is proposed. The received signal strength indicator (RSSI) is used as database values which correspond to the location of the sensor nodes. Fuzzy C-Means (FCM) clustering algorithm is applied as the experiment data cluster method. FCM algorithm is deployed to cluster the obtained feature vectors into several classes corresponding to the different amount of RSSI values. The results show that FCM can cluster the target node in a group of the fingerprint database. The location of target node is arranged in various forms to validate the accuracy of the clustering technique. Euclidean distance is used as the parameter to compare the similarity between fingerprint database and the target location. The results show that the new method is simple and effective method to reduce the complexity and to support the low power and to reduce the time using in the fingerprint-based localization technique. © 2011 IEEE.
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Three-ray path loss based on peak power loss for ultra wideband impulse radio systems
(2011-12-01)
Supanakoon, Pichaya
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Chaiyapong, Saksit
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Promwong, Sathaporn
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Takada, Jun Ichi
Path loss is important parameter to analyze and design link budget. For indoor environment, there is fading that occurs in path loss. Therefore, accurate path loss model, which is considered fading, is necessary. In this paper, three-ray path loss based on peak power loss is proposed for ultra wideband impulse radio (UWB-IR) systems. The rectangular passband is used as UWB-IR transmitted signal. The extension of Friis' transmission formula is applied for UWB-IR three-ray channel. The received signal is evaluated. The closed form formula of three-ray path loss is derived based on peak power loss. The path loss from proposed model was illustrated and compared with three-ray model based on average power loss and free space model. This model can be used to study the characteristic of fading and extended to multi-ray path loss model for indoor environment. © 2011 IEEE.
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Waveform distortion and transmission gain on ultra wideband impulse radio
(2010-01-01)
Promwong, Sathaporn
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Supanakoon, Pichaya
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Takada, Jun Ichi
A waveform of an ultra wideband impulse radio (UWBIR) system can be extremely distorted through a channel even for free-space transmission because of antenna dispersion. This highly degrades the link budget performance. Therefore, the understand of antenna characteristics, which effects on waveform distortion, is necessary. This paper studies the waveform distortion due to antenna in free space transmission in UWB-IR system. The link budget is usually evaluated by using the Friis' transmission formula. However, it is not directly applicable to the UWB-IR transmission system. The link budget evaluation formula attended from conventional Friis' transmission formula that takes into account the transmitted waveform, its distortion due to the antennas, the channel and the correlation receiver is proposed. Since the antenna is significant pulse-shaping filters in UWB-IR system, the example kind of the log-periodic dipole antenna (LPDA) is experimentally examined, especially focused on the effect of the template waveforms. Copyright © 2010 The Institute of Electronics, Information and Communication Engineers.
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Signal subspace interpolation from discrete measurement samples In constructing a database for location fingerprint technique
(2009-01-01)
Cherntanomwong, Panarat
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Takada, Jun Ichi
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Tsuji, Hiroyuki
In this paper, a method of the signal subspace interpolation to constructing a continuous fingerprint database for radio localization is proposed. When using the fingerprint technique, enhancing the accuracy of location estimation requires very fine spatial resolution of the database, which entails much time in collecting the data to build up the database. Interpolated signal subspace is presented to achieve a fine spatial resolution of the fingerprint database. The angle of arrival (AOA) and the measured signal subspace at known locations are needed to obtain the interpolated signal subspaces. The effectiveness of this method is verified by an outdoor experiment and the estimated location using this method was compared with those using the geometrically calculated fingerprint and the measured signal subspace fingerprint techniques. Copyright © 2009 The Institute of Electronics, Information and Communication Engineers.
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SNR gain analysis of ultra wideband template receiver for wireless personal area networks
(2008-12-01)
Keoalounxay, Sengaloun
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Promwongttt, Sathaporn
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Boonsingt, Wiphanee
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Sukutamatanti, Nikorn
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Takada, Jun Ichi
In this paper, we evaluated the signal to noise ratio (SNR) gain of ultra wideband (UWB) receivers performance for wireless personal area network. The optimum and isotropic template receivers are considered based on the data measurement. The biconical antennas are used as the transmitter (Tx) and receiver (Rx) antennas. The rectangular passband, which is satisfied the full band of UWB signal definition and Federal Communications Commission (FCC) indoor and outdoor limit spectral masks, is used as the transmitted UWB signal. The channels are measured in an anechoic chamber by using a vector network analyzer (VNA). The SNR gains of optimal and isotropic template receivers are shown and compared in results. copyright © 2008 IEICE.

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