• The Journal of the Korea Contents Association
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• v.13 no.1
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• pp.9-18
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• 2013

In order to measure the parameters of consumers' preferred image quality, this research suggests image quality assessment factors; dynamic range, color, and contrast. They have both physical image quality factors and psychological characteristics from the previous researches. We found out the specific ranges of preferred image quality metrics. As a result, Digital Zone System meant for dynamic range generally shows 6~10 stop ranges in portrait, nightscape, and landscape. Total RGB mean values represent in portrait (67.2~215.2), nightscape (46~142), and landscape (52~185). Portrait total RGB averages have the widest range, landscape, and nightscape, respectively. Total scene contrast ranges show in portrait (196~589), nightscape (131~575), and landscape (104~767). Especially in portrait, skin tone RGB mean values are in ZONE V as the exposure standard, but practically image consumers' preferred skin tone level is in ZONE IV. Also, total scene versus main subject contrast ratio represents 1:1.2; therefore, we conclude that image consumers prefer the out-of-focus effect in portrait. Throughout this research, we can measure the preferred image quality metrics ranges. Also, we expect the practical and specific dynamic range, color, and contrast information of preferred image quality to positively influence product development.

• KIPS Transactions on Software and Data Engineering
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• v.5 no.4
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• pp.195-202
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• 2016

There have been many studies on subject tests for 3D contents using 3D glasses, but there is a limited research for 3D contents using autostereoscopic display. In this study, we investigated to assess usability of electroencephalogram (EEG) as an objective evaluation for 3D contents with different quality using autosteroscopic display, especially for lenticular lens type. The image with optimal quality and the image with distorted quality were separately generated for autostereosopic display with lenticular lens type and displayed sequentially through lenticular lens for 26 subjects. EEG signals of 8 channels from 26 subjects exposed to those images were detected and correlation between EEG signal and the quality of 3D images were statistically evaluated to check differences between optimal and distorted 3D contents. What we found was that there was no statistical significance for a wave vibration, however b wave vibration shows statistically significant between optimal and distorted 3D contents. b wave vibration observed for the distorted 3D image was stronger than that for the optimal 3D image. This results suggest that subjects viewing the distorted 3D contents through lenticular lens experience more discomfort or fatigue than those for the optimum 3D contents, which resulting in the greater b wave activity for those watching the distorted 3D contents. In conclusion, these results confirm that electroencephalogram (EEG) analysis can be used as a tool for objective evaluation of 3D contents using autosteroscopic display with lenticular lens type.

• Journal of Digital Convergence
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• v.13 no.9
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• pp.351-359
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• 2015

This convergence study analyzed the effectiveness of digital radiography system of copper(Cu) filter in the added filtration for the removal of lower energy radiation through dose and image evaluation. We were analyzed from April to June 2015 result of the examination. Cu filter was applied to each non, 0.1, 0.2, 0.3 mm according to change of kV and mAs and doses were evaluated. Image quality was evaluated by PSNR, MAE, MSE, CNR, SNR and qualitative analysis was performed by seven items for resolution and contrast from chest x-ray criteria of national cancer checkup. The absorbed doses with Cu were lowered by 16-88 % than non-filter but the gaps decreased as kV increased. PSNR were over 30 dB and all significant and CNR and SNR were superior with non-filter but in the qualitative analysis, there were different statistical significant according to each item. The score of 0.1 mm filter was high at pulmonary blood vessel observation and in the 0.3 mm Cu, there were no statistical signigicant except high density and full of air portion. Cu filter can improve image quality with lower radiation dose using better radiation quality and correction power at digital radiography system.

• Journal of radiological science and technology
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• v.33 no.4
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• pp.341-348
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• 2010

By accessing the current status of FPD system use in the hospitals located in Seoul and Gyeonggi Province as well as the entrance skin dose and the image quality evaluation realized by C-D Phantom, and the image assessment by the medical professionals regarding the radiography for the extremity, the following results were derived. 1. According to the evaluation made in the actual use of FPD system (12 machines), the grid ratio varied from 8:1 to 13:1, and 6 machines used the grid ratio with 12:1, realizing the largest number. Among the machines, there were 8 machines that allowed a removable grid while 3 machines did use a removable grid (25.0%). 2. When it came to the equipments used for the experiment, it showed that the amount of the entrance skin dose increased from 4.13 times up to 4.79 times with the grid use. 3. The difference in the entrance skin dose depending on the changes in the exposure condition(0.5times or 2.0times) was not significantly different regardless of the patients' thickness. 4. In terms of the image quality depending on C-D Phantom, the grid use was distinguished well. However, the images were well distinguishable as the exposure condition got increased. 5. In the clinical assessment, the grid use was less effective for the Hand PA, which was considered to shoot a thin body part. It was evaluated that the grid use was preferred for the Knee AP, which was shooting for a relatively thick body part. Nonetheless, 3 out of 5 people said that they would not use the grid if the entrance skin dose to reduced.

• Journal of the Korean Society of Radiology
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• v.16 no.3
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• pp.203-209
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• 2022

One of the typical methods for lowering radiation dose while maintaining image quality of computed tomography (CT) is the use of model-based iterative reconstruction (MBIR). This study is to evaluate the image quality by adjusting the strength of the advanced modeled iterative reconstruction (ADMIRE), which is well known as a representative model of MBIR. The study was conducted using phantom, and CT images were obtained while adjusting the strength of ADMIRE in units of 1 to 5. Quantitative evaluation includes noise levels using coefficient of variation (COV) and contrast to noise ratio (CNR), as well as natural image quality evaluation (NIQE) and blind/referenceless image spatial quality evaluator (BRISQUE). As a result, in both noise level and blind quality evaluation results, the higher the strength of ADMIRE, the better the results were derived. In particular, it was confirmed that COV and CNR were improved 1.89 and 1.75 times at ADMIRE 5 compared to ADMIRE 1, respectively, and NIQE and BRISQUE were proved to be improved 1.35 and 1.22 times at ADMIRE 5 compared to ADMIRE 1, respectively. In conclusion, this study was proved that the reconstruction strength of ADMIRE had a great influence on the noise level and overall image quality evaluation of CT images.

• Journal of Broadcast Engineering
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• v.3 no.1
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• pp.69-84
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• 1998

In digital broadcasting, services such as digital satellite TV, cable TV and digital terrestrial TV, several video programs are compressed by MPEG-2, and then simultaneously transmitted over a conventional CBR (Constant Bit Rate) broadcasting channel. In this paper, we propose a joint quality control scheme to be able to accurately control the relative picture quality among the video programs, which is achieved by simdt;,nL'Ously controlling the video encoders to generate the VBR (Variable Bit Rate) compressed video streams. Our quality control scheme can prevent the video buffer overflow and underflow by total target bit allocation process, and also exactly control the relative picture quality in terms of PSNR (Peak Signal to Noise Ratio) between some programs requiring higher picture quality and others by rate-distortion modification. Furthermore we present a rate-distortion estimation method for MPEG-2 video, which is base of our joint quality control, and verify its performance by experiments. The most attractive features of this estimation method are as follows: 1) computational complexity is low because main operation for the estimation is to calculate the histogram of OCT coefficients into quantizer; 2) estimation results are very accurate enough to be applied to the practical MPEG-2 video coding applications. Simulation results show that the proposed joint quality control scheme accurately controls the relative picture quality among the video progran1s transmitted over a single channel as well as provides more consistent and higher picture quality than independent coding scheme that encodes each program independently.

• The Magazine of the IEIE
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• v.37 no.2
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• pp.55-64
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• 2010

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.5
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• pp.13-20
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• 2007

• Journal of radiological science and technology
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• v.18 no.2
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• pp.3-14
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• 1995

• Proceedings of the Korean Society of Radiological Science
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• 1996.10a
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• pp.94-95
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• 1996