• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.6
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• pp.22-34
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• 2010

Existing image scalers generally adopt simple interpolation methods such as bilinear method to take cost-benefit, or highly complex architectures to achieve high quality resulting images. However, demands for a low power, low cost, and high performance image scaler become more important because of emerging high quality mobile contents. In this paper we propose the novel low power hardware architecture for a high quality raster scan image scaler. The proposed scaler architecture enhances the existing cubic interpolation look-up table architecture by reducing and optimizing memory access and hardware components. The input data buffer of existing image scaler is replaced with line memories to reduce the number of memory access that is critical to power consumption. The cubic interpolation formula used in existing look-up table architecture is also rearranged to reduce the number of the multipliers and look-up table size. Finally we analyze the optimized parameter sets of look-up table, which is a trade-off between quality of result image and hardware size.

• Journal of radiological science and technology
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• v.28 no.4
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• pp.273-277
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• 2005

The rapid development in digital acquisition technology in radiography has not been accompanied by information regarding optimum radiolographic technique for use with an amorphus silicon flat panel detector. The purpose of our study was to compared image quality and radiation dose of an amorphus silicon flat panel detectors for digital chest radiography. All examinations were performed by using an amorphus silicon flat panel detector. Chest radiographs of an chest phantom were obtained with peak kilovoltage values of $60{\sim}150kVp$. Published data on the effect of x-ray beam energy on image quality and patient dose when using an amorphus silicon flat panel detector. It is important that radiographers are aware of optimum kVp selection for an amorphus silicon flat panel detector system, particularly for the commonly performed chest examination.

• Journal of the Korean Society of Radiology
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• v.13 no.2
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• pp.227-232
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• 2019

MRI examination for patients with metal objects has in poor image quality. Metallic implants can result in poor image because magnetic susceptibility causes signal loss and distortion and makes poor imaging, which is called magnetic susceptibility artifact or metal artifact. There are several approaches to reduce metal artifacts. In this study, we study the reduction of metal artifact by VAT and SEMAC techniques. A metal implant used for orthopedic surgery was attached to the phatom and the distortion caused by the artifact was measured under T1WI and T2WI protocols. Several techniques of VAT only and VAT and SEMAC for the reduction of metal artifact were compared. The metal artifact showed a reduction of at least 8% to a maximum of 26% in the VAT-SEMAC. The VAT-SEMAC technique can be applied to patients with orthopedic implants to improve image quality. If scan time and image quality are simultaneously considered in VAT-SEMAC technique, metal artifact will be reduced in clinical practice.

• Journal of the Korean Society of Radiology
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• v.10 no.5
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• pp.367-373
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• 2016

This study conducted an analysis to compare the differences in the properties of the magnetic field and the generation of artifacts because of the difference in the magnetic field between 1.5 T equipment and 3.0 T equipment, centering around four types of pulse sequences, mainly applied to the abdominal Magnetic Resonance Imaging (MRI). With data on 500 persons transmitted to the PACS, this study analyzed the SNR value, quantitatively and carried out a qualitative evaluation, dividing MSA, CSA, and DA into three steps. As a result of the quantitative evaluation, the SNR value was significantly higher in the 1.5 T equipment; however, there was a factor deteriorating the image quality, too, as artifacts were generated in the images. The 1.5 T equipment generated fewer artifacts than the 3.0 T equipment did, so it could compensate the image quality for 3.0 T. In conclusion, based on these findings, this study could understand the differences in the properties of the magnetic field and the generation of artifacts occurring because of the difference in the magnetic field and could provide a measure for them. This study would be guidelines for MRI users who directly examine the patients in abdominal MRI using the two types of equipment in the clinical setting in the future.

• Journal of radiological science and technology
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• v.27 no.2
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• pp.7-12
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• 2004

MDCT is a useful, non-invasive, diagnostic tool in the evaluation of coronary artery disease. However, the image quality is affected by an irregular heart rhythm of the patients. Especially, premature ventricular contraction induced stair-step artifacts in the reconstruction of 2-D or 3-D images of the heart including coronary arteries. In recent, we experienced some improving of the image quality after correcting the PVC. Accordingly, the purpose of our study was to evaluate the effectiveness of the arrhythmia correction method, which was commercially available software, in improving the quality of the reconstruction images of the heart. Image analysis was performed, in consensus, by two radiologists. The scores for image quality were ranked as follows; excellent is 4 (image quality is markedly improved and is helpful in the image evaluation), good is 3 (image quality is mildly improved, but is somewhat helpful in the image evaluation), fair is 2 (image quality is improved and is not helpful in the image evaluation), and poor is 1 (image quality is not improved). We used ANOVA method to evaluate the statistical significant differences in the image qualities among the correction methods of the arrhythmia with below 0.05 of p-value. The method of moving the R-R interval showed statistically significant differences in improving of the image quality in patients with arrhythmia. We concluded that the regulation of R-R interval in patients with arrhythmia was an effective method to improve the image quality in the reconstructions of the MDCT coronary angiograms.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.131-134
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• 2006

본 논문은 고화질 이미지를 MPEG-2 스트리밍 기반에 전송하는 방법을 제안한다. 본 논문에서 제안한 연구는 기존 연구에서는 다루지 않았던 고화질 이미지에 대한 부분을 다룰 것이며 제안된 환경은 DVB-ASI(Digital Video Broadcasting-Asynchronous Serial Interface) PCI 카드에서 입력받은 MPEG-2 스트리밍 데이터를 실시간으로 표준출력 장치에 디스플레이하며 송신 측과 수신 측에서 사용될 MPEG-2 스트리밍 헤더를 제안한다. 제안한 모듈 시험 결과 동영상 전송과 더불어 고화질 이미지 수신이 실시간으로 디스플레이 되었으며 시스템 점유율이 낮게 측정되었다.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10a
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• pp.122-124
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• 2000

본 논문은 질병이 있는 뇌종양 MRI 이미지 검색을 위해 아이콘 기반의 스케치 질의 방안을 제시한다. 기존의 이미지 검색 시스템은 이미지가 갖는 속성 중 일부의 속성 값만을 가지고 사용자가 직접 질의 이미지를 작성한다. 그러나 이런 방법으로는 여러 복잡한 속성값을 갖는 뇌종양 MRI 이미지의 내용을 표현하기는 어렵다. 그래서 본 논문에서는 질병이 있는 뇌 MRI 이미지 검색을 위해 아이콘을 사용한 템플릿 형식의 메디컬 스케치 질의 방법을 제시한다. 뇌에서 발생하는 뇌질환을 질병별로 분류하였고, 분류된 질병들이 가지고 있는 색상이나 질감, 모양과 같은 속성 값들을 아이콘화하여 템플릿 이미지로 제공되는 정상인의 이미지에 정의된 질병 아이콘의 크기와 위치를 설정함으로써 사용자가 검색하고자 하는 질의 이미지를 쉽게 작성할 수 있는 스케치 형식의 질의방법을 제안한다.

• Korean Journal of Remote Sensing
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• v.33 no.6_1
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• pp.1003-1017
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• 2017

Multispectral image data of high spatial resolution is required to obtain correct information on the ground surface. The multispectral image data has lower resolution compared to panchromatic data. PAN-sharpening fusion technique produces the multispectral data with higher resolution of panchromatic image. Recently the object-based approach is more applied to the high spatial resolution data than the conventional pixel-based one. For the object-based image analysis, it is necessary to perform image segmentation that produces the objects of pixel group. Image segmentation can be effectively achieved by the process merging step-by-step two neighboring regions in RAG (Regional Adjacency Graph). In the satellite remote sensing, the operational environment of the satellite sensor causes image degradation during the image acquisition. This degradation increases variation of pixel values in same area, and results in deteriorating the accuracy of image segmentation. An iterative approach that reduces the difference of pixel values in two neighboring pixels of same area is employed to alleviate variation of pixel values in same area. The size of segmented regions is associated with the quality of image segmentation and is decided by a stopping rue in the merging process. In this study, the image restoration and segmentation was quantitatively evaluated using simulation data and was also applied to the three PAN-sharpened multispectral images of high resolution: Dubaisat-2 data of 1m panchromatic resolution from LA, USA and KOMPSAT3 data of 0.7m panchromatic resolution from Daejeon and Chungcheongnam-do in the Korean peninsula. The experimental results imply that the proposed method can improve analytical accuracy in the application of remote sensing high resolution PAN-sharpened multispectral imagery.

• Investigative Magnetic Resonance Imaging
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• v.15 no.2
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• pp.146-153
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• 2011

Purpose : To describe normal anatomy and compare the differences of external genital organs and urethra on MR imaging in pre- and postmenopausal women. Materials and Methods : A total of 19 pre- and 18 postmenopausal healthy women underwent pelvis MR imaging at 1.5 T. Two radiologists retrospectively scored and compared the image quality of female external genitalia and urethra on axial T2-weighted images (T2WI) and axial fat-suppressed contrast-enhanced T1-weighted images (FSCE-T1WI) by using Wilcoxon signed ranks test. The radiologists compared the wall thickness or size of external genital organs and urethra on FSCE-T1WI between two groups by using Student t test. Results : Image quality was better with FSCE-T1WI than with T2WI in all subjects (p < 0.05). The vestibular bulb, clitoris and labium minor were more clearly visualized on FSCE-T1WI in premenopausal subjects rather than in postmenopausal subjects (p < 0.05). The urethra had a target-like appearance with three layers in premenopausal and postmenopausal subjects. Postmenopausal subjects were observed to have significantly smaller vaginal wall thickness, urethral wall thickness and vestibular bulb width than premenopausal subjects (p < 0.05). Conclusion : The anatomy and morphologic changes of female external genital organs and urethra were well discernible on FSCE-T1WI.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.04a
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• pp.261-264
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• 2002

자동차 전조등에서 나오는 데이터는 다양한 패턴을 가지는 영상자료와 부분적으로 보이는 문자자료이다. 내용기반 영상검색을 통해 자동차 전조등에서 검사자가 판독하는 텍스트와 부분적인 전조등의 영상정보로 차량의 정보를 추출하기 위한 검색 방법을 국립과학수사연구소의 자료를 기반으로 설계하였으며, 영상검색에 사용된 영상특징값의 구성과 영상 검색방법을 연구하였다. 본 논문에서는 영상데이터의 검색을 위해 효과적인 영상특징이 추출 되도록 향상된 방법론을 제시하였다. 특징함수에 대한 유효성 검증을 위해 샘플 영상에서 각 후보 특징함수들에 대한 결과값들을 비교하였으며, 이를 기반으로 유효한 특징함수를 찾아서 검색에 사용되어지도록 구성하였다. 사용되어진 영상의 특징값은 전조등 영상이 가지는 다수의 텍스쳐함수와 가로, 세로 성분값을 사용하였다. 영상 검색을 위해 추출된 영상 특징값을 데이터베이스화하고 용의차량의 전조등 영상을 질의 영상으로 하여 후보 차량에 대한 정보를 검색하도록 하였다.