• Korean Journal of Optics and Photonics
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• v.22 no.1
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• pp.10-15
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• 2011

In this paper, we propose an auto-focusing algorithm which extracts a depth parameter by analyzing a selected part of a hologram, and we use experimental results to show that the algorithm is practical. First, we record a complex hologram using Optical Scanning Holography. Next we select some part of hologram and extract depth information through Gaussian low pass filtering, synthesizing a real-only hologram, power fringe-adjusted filtering and inverting to a new frequency axis. Finally, we reconstruct the hologram automatically using the extracted depth location.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.4
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• pp.553-563
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• 1994

This paper presents a filtering method using neural networks to extract fundamental frequency components of the transient wave signals in power systems. Based on the ability of multilayer feedforward neural networks to approximate any continuous function, a neural networks mapping filter is proposed for the protective distance relaying systems to extract the effective components efficiently. A characteristic feature of this mapping filter is composed of the multilayer perceptron neural networks which are trained by using random signals and those are mapped to the DFT filtering computational structure by GDR(Generalized Delta Rule). The advantage of this approach is demonstrated by the random waves and the fault transient wave signals of EMTP(electromagnetic transients program) in power systems fault conditions. The proposed method is compared with the conventional method and the simulation results show the efficiency of the neural networks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.12 no.2
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• pp.176-188
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• 1987

This paper presents a method for Digital Image Motion Restoration by inverse filtering. In order to onstruct optimal Restoration filter, We exactly have to model the degradation process, and therefrom, derive the inverse filter which has inverse charateristics of the degradation model. An Image taken from object which moves fast, is o suffer blurring. it can be modeled by integration process mathematically and analyzed to convolve a rectangular window over an image. in this paper, We analyzed it in the frequency domain, and studied a method for motion restoration using inverse filter has a directional Sinc property.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.07a
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• pp.69-72
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• 2015

본 논문에서는 디지털 영상 컨텐츠의 저작권 보호를 위해 DWT 를 이용하여 강인성(robustness), 비가시성(invisibility), 보안성(security)을 만족하는 blind 워터마킹 방법을 제안한다. 이 방법은 영상정보에 대한 변화를 원본 영상의 특정 부분에 국한하지 않게 하기 위해서, 특정 주파수 성분에 워터마크를 삽입하는 것이 아닌 전체 영상에 워터마크를 삽입하는 방법이다. 이 방법에서 저작권에 대한 판단은 추출한 워터마크 정보를 통합 판단하는 방법을 사용한다. 이 방법은 저작권 보호를 위해 원본 영상을 보관할 필요가 없으며, Gaussian filtering, average filtering, sharpening 의 영상 필터링, JPEG 손실 영상 압축, resizing, 영상 품질 향상을 위한 Contrast 나 histogram equalization 등의 공격에 충분한 강인성을 보여준다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.6B
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• pp.1021-1027
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• 2000

In this paper, we propose two new detection-estimation based algorithms that effectively remove impulsive noises in severely corrupted color images. The existing methods for enhancing corrupted color images with impulsive noises commonly possess the inherent problems of excessive computing time and smoothing out edges. However, since our proposed algorithms classify corrupted pixels first in each channel or in each pixel and then perform marginal or vector median filtering only for them, are computationally efficient and preserve edges well. In addition, since there are no appropriate criteria to evaluate the performance of impulsive noise detectors for color images, the objective comparison of noise detectors is difficult. Thus, we introduce a new efficiency factor to compare the performance of noise detectors in digital color images. Simulation results show that the proposed algorithms perform better than the existing methods in terms of both objective and subjective evaluat ons.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.05
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• pp.143-146
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• 1996

An adaptive digital filtering of the electroencophalogram(EEG) is a successful way of suppressing mains interference, but it affects some of the frequency components of the signal, an artifact which not be acceptable in some cases of automatic EEG processing. The types of electrical artifact seen on EEG records is described. Those are the EOG and the PVC roller pump noise. And we study the method for cancelling these artifacts. The method does not need the reference channel, and are obtained by cascading the linear predictor and the noise canceller. The simulation results illustrate the performances of the presented method in terms of the capability of interferences suppression.

• Journal of Biomedical Engineering Research
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• v.29 no.1
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• pp.46-51
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• 2008

We describe a backprojection filtering method for limited angle tomography. In order to reduce blur artifacts originated from the out-of-planes and control high-frequency noise, we employed two band-limited window functions, and which were realized by Hann filters in this study. Based on the experimentally measured data, the performance of the developed method is demonstrated by comparing with the conventional shift-and-add and filtered backprojection methods. Application of the developed method to the dental imaging has a potential to be used for the preoperative evaluation of the jaw for dental implants with much reduced patient dose instead of the conventional dental computed tomography.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.407-407
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• 2002

The most widespread techniques for DEM generation are stereoscopy for optical sensor images and interfereometry for SAR images. These techniques suffer from certain sensor and processing limitations, which can be overcome by the synergetic use of both sensors and DEMs respectively. In this paper, different strategies for fusing SAR and optical data are combined to derive high quality DEM products. The filtering techniques, which take advantage of the complementary properties of SAR and stereo optical DEMs, will be applied for the fusion process. By taking advantage of the fact that errors of the DEMs are of different nature using the filtering technique, affected part are filtered and replaced by those of the counterpart and is tested with two sets of SPOT and ERS DEM, resulting in a remarkable improvement in DEM. for the analysis of results, the reference DEM is generated from digital base map(1:5000).

• Proceedings of the Korea Multimedia Society Conference
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• 2002.05c
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• pp.315-319
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• 2002

The study on shilla monumental inscription has been accomplished by many historians. However, the research on segmentation of monumental inscription image using digital image processing technique is not sufficient. The preprocessing using computer is needed for accurate interpretation of history. In this paper, A morphological filtering using directional information is presented. Directional filtering is effective in reducing noises and preserving edges. The opening and closing operations in the 1st stage are performed for the pixel is aligned to the vertical, horizontal and two diagonal directions. The Opening operation supresses the positive impulse noise while the closing operation the negative ones. Then Directional filter and post-processing are applied to the image. Experimental result shows outstanding performance for interpretation.

• ETRI Journal
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• v.35 no.4
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• pp.697-705
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• 2013

Emerging trends in the area of digital very large scale integration (VLSI) signal processing can lead to a reduction in the cost of the cochlear implant. Digital signal processing algorithms are repetitively used in speech processors for filtering and encoding operations. The critical paths in these algorithms limit the performance of the speech processors. These algorithms must be transformed to accommodate processors designed to be high speed and have less area and low power. This can be realized by basing the design of the auditory filter banks for the processors on digital VLSI signal processing concepts. By applying a folding algorithm to the second-order digital gammatone filter (GTF), the number of multipliers is reduced from five to one and the number of adders is reduced from three to one, without changing the characteristics of the filter. Folded second-order filter sections are cascaded with three similar structures to realize the eighth-order digital GTF whose response is a close match to the human cochlea response. The silicon area is reduced from twenty to four multipliers and from twelve to four adders by using the folding architecture.