Browsing by Author "Chen, Yu-Ta"

Now showing 1 - 9 of 9

A Gray Level Weighting Method to Reduce Optical Aberration Effect in Holographic Data Storage System
(2011-03-01)
Ou-Yang, Mang
;
Chen, Yu-Ta
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
An alignment method for holographic data storage system (HDSS) is proposed in this paper. Due to several types of noises encountered in the HDSS, the signal-to-noise ratio (SNR) is degraded. Errors can be corrected using a channel code for some sorts of noise, while it may require a high quality optical system to reduce the error probability for the other types of noise. A checkerboard pattern is proposed using intensity weighting to find the fiducial points, which could work in a lower SNR system and thus reduce the error likelihood effectively. Reed-solomon (RS) code and oversampling are both made available in the HDSS. As a consequence, the aberration effects are eliminated using the fiducial points, leading to a low SNR system clear of errors after performing decoding. The lowest SNR system is out of error-free recovery condition, so that all the alignment methods proposed in this paper could not reduce the aberration effects to restore the images into the original data.
A recognition method in holographic data storage system by using structural similarity
(2013-01-01)
Chen, Yu-Ta
;
Ou-Yang, Mang
;
Lee, Cheng-Chung
;
電機工程學系
;
Department of Electrical and Computer Engineering
The holographic data storage system (HDSS) is a page-oriented storage system with advantages of great capacity and high speed. The page-oriented recording breaks the tradition of the optical storage of one-point recording. As the signal image is retrieved from the storage material in the HDSS, various noises influences the image and then the data retrieve will be difficultly from the image by using the thresholding method. For progressing on the thresholding method, a recognition method, based on the structural similarity, is proposed to replace the thresholding method in the HDSS. The recognition method is implemented that the image comparison between the receive image and reference image is performed by the structural similarity method to find the most similar reference image to the received image. In the experiment, by using recognition method, the bit error rate (BER) results in 26% decrease less than using the thresholding method in the HDSS. Owing to some strong effects, such as non-uniform intensity and strong speckle, still influencing on the received image, the recognition method is seemed to be slightly better than thresholding method. In the future, the strong effects would be reduced to improve the quality of the receive image and then the result of using the recognition method may be vastly better than the thresholding method.
Design of illumination system in ring field capsule endoscope
(2011)
Jeng, Wei-De
;
Mang Ou-Yang
;
Chen, Yu-Ta
;
Wu, Ying-Yi
;
電控工程研究所
This paper is researching about the illumination system in ring field capsule endoscope. It is difficult to obtain the uniform illumination on the observed object because the light intensity of LED will be changed along its angular displacement and same as luminous intensity distribution curve. So we use the optical design software which is Advanced Systems Analysis Program (ASAP) to build a photometric model for the optimal design of LED illumination system in ring field capsule endoscope. In this paper, the optimal design of illumination uniformity in the ring field capsule endoscope is from origin 0.128 up to optimum 0.603 and it would advance the image quality of ring field capsule endoscope greatly.
Evaluation of video quality by CWSSIM method
(2010-01-01)
Chen, Yu-Ta
;
Hsu, Shau-Wei
;
Pong, Bao-Jen
;
Mang Ou-Yang
;
電控工程研究所
Several estimative factors of image quality have been developed for approaching the human perception objectively(1-3). We propose to take systematically distorted videos into the estimative factors and analyze the relationship between them. Several types of noise and noise weight were took into COSME standard video and verified the image quality estimative factors which were MSE (Mean Square Error). SSIM (Structural SIMilarity). CWSSIM (Complex Wavelet SSIM). PQR (Picture Quality Ratings) and DVQ (Digital Video Quality). The noise includes white noise, blur and luminance. etc. In the results, CWSSIM index has higher sensitivity at image structure and it could estimate the distorted videos which have the same noise type at the different levels. PQR is similar to CWSSIM, but the ratings of distribution were banded together; SSIM index divides the noise types into two groups and DVQ has linear relationship with MSE in the logarithmic scale.
Gray code encoding and decoding method applied to holographic storage devices
(2009-08-27)
Ou-Yang, Mang
;
Chen, Yu-Ta
;
Sun, Ching-Cherng
;
Yang, Tsung-Hsun
A gray code encoding and decoding method applied to holographic storage devices is proposed. The encoding method uses gray levels of a 2D detector to encode a certain amount of original bits of the original data, and then sends them to a spatial light modulator (SLM) for encryption. The decoding method corrects the received gray levels to the original gray levels, and then compares the maximum gray level with the original gray levels to decode the original gray level into binary data. The proposed encoding and decoding method can better make use of storage locations of the 2D detector and get a code rate close to 1.
Improvement of bit error rate and page alignment in the holographic data storage system by using the structural similarity method
(2012-06-01)
Chen, Yu-Ta
;
Ou-Yang, Mang
;
Lee, Cheng-Chung
;
電機工程學系
;
Department of Electrical and Computer Engineering
Although widely recognized as a promising candidate for the next generation of data storage devices, holographic data storage systems (HDSS) incur adverse effects such as noise, misalignment, and aberration. Therefore, based on the structural similarity (SSIM) concept, this work presents a more accurate locating approach than the gray level weighting method (GLWM). Three case studies demonstrate the effectiveness of the proposed approach. Case 1 focuses on achieving a high performance of a Fourier lens in HDSS, Cases 2 and 3 replace the Fourier lens with a normal lens to decrease the quality of the HDSS, and Case 3 demonstrates the feasibility of a defocus system in the worst-case scenario. Moreover, the bit error rate (BER) is evaluated in several average matrices extended from the located position. Experimental results demonstrate that the proposed SSIM method renders a more accurate centering and a lower BER, lower BER of 2 dB than those of the GLWM in Cases 1 and 2, and BER of 1.5 dB in Case 3. (C) 2012 Optical Society of America
Measurement of binocular disparity in polarized based stereoscopic display by using digital camera
(2013-06-01)
Chen, Yu-Ta
;
Hsu, Shau-Wei
;
Pong, Bao-Jen
;
Ou-Yang, Mang
;
Lee, Cheng-Chung
This work presents an image displacement measurement by using a box pattern and the edge spread function analysis in the polarized based stereoscopic displays. The measurement determines to identify three factors (i.e., box size, image displacement, and spatial frequency response (SFR)) from the box patterns. The polarized based stereoscopic displays might sacrifice pixels for producing 3D images, which might produce errors in the image displacement and then affect the depth perception indirectly. Based on the measurement, the errors can be quantified by using the three factors. Owing to the light leakage distorting the edge spread function to obtain an inferior SFR, exactly how light leakage affects the edge spread function can be resolved on the basis of the SFR results, especially at a frequency (1/display pixel) of 1.9 in the case of the horizontal displacement. Light leakage also induces the error of the box height in even and odd intervals of the vertical displacements more than 2pixels and 0.5pixels, respectively. The image displacement measurement provides a simple and comprehensive means of evaluating the optical characteristics, disparity, and sharpness of the stereoscopic displays, via the three factors.
Portable noninvasive system for oral cancer diagnosis
(2012)
Yang, Chin-Siang
;
Ou-Yang, Mang
;
Hsieh, Yao-Fang
;
Chen, Yu-Ta
;
Chiou, Jin-Chern
This study presents a portable noninvasive detection system which can get the image of specific spectral immediately, that promote to oral cancer diagnosis. According to research literature show the performance called autofluorescence of cells after exciting by specific wave band of light. It is different of the spectrum distribution for lesions of epithelial cells and normal cells after fluorescence excite, that is a basis of diagnosing to oral cancer. The convenient equipment for detection of oral cancer is modified for existing handheld microscope. From Fig. 1, the UV LED illuminates to the surface of object and excites the cells which produce fluorescent reaction and showed the image with specific wavelength. The image passes through the central channel and filter out unwanted spectral by the selection of filter, and focused by the focus lens on the image sensor, therefore we can achieve the specific wavelength image via fluorescence reaction.
Using Ensemble Empirical Mode Decomposition to Improve the Static Fringe Analysis in Optical Testing
(2012)
Chen, Yu-Ta
;
Mang Ou-Yang
;
Wu, Shuen-De
;
Lin, Shiou-Gwo
;
Kuo, Yi-Ting
Static fringe analysis is an important skill to reconstruct the surface profile of the tested optics. The mixed image is simulated by the tilt aberration, and several methods of the reducing mixing fringe are utilized to reconstruct the optical paths difference (OPD) profile of the mixed image. In this paper, we propose the ensemble empirical mode decomposition (EEMD) method to decompose the mixed image into several intrinsic mode functions (IMFs), and then removing one or more IMFs to reduce the influence of the mixing fringe in the mixed image. The procedure of reducing mixing fringe can reconstruct the OPD profile of the mixed image easily. In the simulation, using EEMD to reduce the influence of the mixing fringe, the root mean square (RMS) value of the OPD is 0.081 waves as the residue image subtracted from the OPD profiles of original image. In the experiment, the EEMD method reducing the noise of the mixing fringe has the advantage on the high frequency as spherical aberration.