• Journal of radiological science and technology
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• v.41 no.5
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• pp.391-396
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• 2018

The purpose of this study was to compare and analyze the patient dose according to the distance between the X-ray tube focus and the image receptor, and to propose a new method for quantitatively evaluating the image quality. Using this quantitative evaluation method, the optimal distance for increasing x-ray image quality with low radiation dose was estimated between source and image receptor in Rib series radiography. Phantom images were obtained by changing the distance between focus and image receptor (100 cm and 180 cm). The patient radiation dose was estimated using entrance surface dose and dose area product. In order to evaluate image quality objectively, a non - reference image evaluation method was employed with paper and salt noise and Gaussian filter. As a result of this study, when the SID was changed from 100 cm to 180 cm, the entrance surface dose decreased by 4 ~ 5 times and the dose area product decreased by 3 times. In addition, there is no significant difference in image quality between of SID 180 cm and SID 100 cm. In conclusion, it was demonstrated that performing the rib series radiography at SID 180 cm is an optimal method to reduce the exposure dose and improve the image quality.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.397-400
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• 2004

Synthetic Aperture Radar(SAR) is an active micro­wave instrument that performs high-resolution observation under almost all weather conditions. Although there are many advantages of SAR instrument, many complicated steps are involved in order to generate SAR image products. Many research and algorithms have been proposed to process radar signal and to increase the quality of SAR products. However, it is hard to find research which compare the quality of SAR products generated with different algorithms and processing methods. In our previous research, a SAR processing s/w was developed for a ground station. In addition, quality assessment procedures and their test parameters inside a SAR processor was proposed. The purpose of this paper is to evaluate the quality of SAR images generated from the developed SAR processing s/w. However, If there are no direct measurements such as radar reflector or scattering field measurement values it is difficult to compare SAR images generated with different methods. An alternative procedures and parameters for SAR image quality evaluation are presented and the problems involved in the comparison methods are discussed. Experiments based on real data have been conducted to evaluate and analyze quality of SAR images.

• The Journal of the Korea Contents Association
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• v.14 no.6
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• pp.247-254
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• 2014

For the purpose of early diagnosis of the breast cancer, the attention on the screening mammography has been increasing-with supply of digital mammography day by day. Image quality is decided by target materials and filter combinations. Optimized selection by a glandular density and a thickness is needed, because these combinations change x-ray spectrum and effect to image quality. The purpose of this study is to find out optimized target and filter combinations through the evaluation of quantitative image quality and to suggest means which minimize patient dose through MCNPX. In results, spatial frequency resolution evaluation which is quantitative image quality evaluation method, MTF, NPS, DQE shows that we have to select Mo/Mo combinations or Mo/Rh combinations when compressed breast is thin. but in case of that when compressed breast is thick, we have to select Rh/Rh combinations or W /Rh combinations. In a comprehensive evaluation, W!Rh combinations which are not used in thin breasts in practice was superior to all image quality evaluation. This result is somewhat different-with clinical examination results. Secondary end point was organ dose evaluation, radiation dose of opposite breast was approximately 47 ~73% effectiveness when selecting standard breast. In conculsion, the most important point is that we have to select the optimal combinations-with considering dose evaluation and various thickness.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.9
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• pp.3672-3684
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• 2015

Recently, the standardization of backward compatible JPEG image coding for high dynamic range (HDR) image has been undertaken to establish an international standard called "JPEG XT." The JPEG XT consists of two layers: the base layer and the residual layer. The base layer contains tone mapped low dynamic range (LDR) image data and the residual layer contains the error signal used to reconstruct the HDR image. This paper gives the result of a study to evaluate the overall performance of tone mapping operators (TMOs) for this standard. The evaluation is performed using five HDR image datasets and six TMOs for profiles A, B, and C of the proposed JPEG XT standard. The Tone Mapped image Quality Index (TMQI) and no reference image quality assessment (NR IQA) are used for measuring the LDR image quality. The peak signal to noise ratio (PSNR) is used to evaluate the overall compression performance of JPEG XT profiles A, B, and C. In TMQI and NR IQA measurements, TMOs using display adaptive tone mapping and adaptive logarithmic mapping each gave good results. A TMO using adaptive logarithmic mapping gave good PSNRs.

• Journal of Korea Multimedia Society
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• v.21 no.11
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• pp.1271-1278
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• 2018

The NDT using ultrasonic is largely divided into A-Scan and C-Scan methods. Since A-Scan method is subject to subjective judgement by trained personnel, C-Scan method has been introduced, which presents the weld area in two dimensions by placing the transducers two dimensionally used in the A-Scan method. Therefore, it is necessary to develop equipment that can provide weld quality without the help of a welding expert and the presentation of effective C-Scan images. Thus, in this paper, the algorithms that express a low resolution 2-dimensional gray image formed by C-Scan method as a high-resolution color C-Scan image and automatically determine the weld quality from the generated C-Scan color image. The high resolution color C-Scan images proposed in this paper allow the exact shape of the weld point to be expressed, and an objective algorithm to use this image to automatically determine weld quality.

• Nuclear Engineering and Technology
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• v.54 no.9
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• pp.3380-3389
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• 2022

We evaluated the performance of an improved hybrid median filter (IHMF) applied to X-ray computed tomography (CT) images obtained using a high-resolution photon-counting cadmium zinc telluride (CZT) detector. To study how the proposed approach improves the image quality, we measured the noise levels and the overall CT-image quality. We established a CZT imaging system with a detector length of 5.12 cm and thickness of 0.3 cm and acquired phantom images. To evaluate the efficacy of the proposed filter, we first modeled two conventional median filters. Subsequently, we were able to achieve a normalized noise power spectrum result of ~10^-8 mm², and furthermore, the proposed method improved the contrast-to-noise ratio by a factor of ~1.51 and the coefficient of variation by 1.55 relative to the counterpart values of the no-filter image. In addition, the IHMF exhibited the best performance among the three filters considered as regards the peak signal-to-noise ratio and no-reference-based image-quality evaluation parameters. Thus, our results demonstrate that the IHMF approach provides a superior image performance over conventional median filtering methods when applied to actual CZT X-ray CT images.

• Textile Coloration and Finishing
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• v.18 no.5 s.90
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• pp.61-71
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• 2006

This paper addresses the factors hindering the image quality of lines in inkjet printed on polyester fabric as printing media. Lines were printed onto different types of polyester fabrics in warp and filling directions. Line image quality including line width, edge blurriness, and edge raggedness was assessed. The effect of capillary wicking on line image quality of printed spun polyester fabric is discussed. The factors on the image quality include printing position(top of the yam or between the yarn), printing direction(warp or filling), yarn structures(filament or spun), thread size(yam or fiber), finishing, and ink properties(evaporation rate). More than 30% differences in image quality results were observed by changing the printing location on the spun polyester fabric. The best results of the image quality were obtained with the printed plain and spun polyester fabrics. The fiber sizes may affect capillary size; therefore, the image quality can be dissimilar. Types of finishing materials and inks greatly improve the line image quality on spun polyester fabrics.

• Journal of the Semiconductor & Display Technology
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• v.9 no.4
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• pp.57-61
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• 2010

The wavelet transform was adopted as the transform for JPEG2000. However, wavelet has weakness about smoothness along the contours and limited directional information. So we use to other transform, called contourlet transform in compression. Objective quality assessment methods currently used Peak signal to noise Ratio(PSNR). But that is not very well matched to perceived visual quality. So new image quality assessment is required. In this paper, we propose a new method for image compression based on the contourlet transform, which has been recently introduced. In addition we evaluated compression image quality using PSNR and SSIM. Finally contourlet transform has a good result about images with smooth contours and SSIM is good method for image evaluation compared to PSNR.

• Journal of the Optical Society of Korea
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• v.10 no.3
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• pp.105-111
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• 2006

A novel image quality evaluation method, which is based on combination of the rigorous grating diffraction theory and the ray-optic method, is proposed. It is applied for design optimization and, tolerance analysis of optical imaging systems implementing diffractive optical elements (DOE). The evaluation method can predict the quality and resolution of the image on the image sensor plane through the optical imaging system. Especially, we can simulate the effect of diffraction efficiencies of DOE in the camera lenses module, which is very effective for predicting different color sense and MTF performance. Using this method, we can effectively determine the fabrication tolerances of diffractive and refractive optical elements such as the variations' in profile thickness, and the shoulder of the DOE, as well as conventional parameters such as decenter and tilt in optical-surface alignments. A DOE-based 2M-resolution camera lens module designed by the optimization process based on the proposed image quality evaluation method shows ${\sim}15%$ MTF improvement compared with a design without such an optimization.

• The Korean Journal of Nuclear Medicine Technology
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• v.12 no.1
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• pp.13-18
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• 2008

Purpose: The image processing method due to the algorism which is various portion nuclear medical image decision is important it makes holds. The purpose of this study is it applies hereupon new image processing method SIEMENS (made by Pixon co.) Onco. flash processing reconstruction and the comparison which use the image control technique of existing the clinical usefulness it analyzes with it evaluates. Materials & Methods: 1. Whole body bone scan-scan speed 20 cm/min, 30 cm/min & 40 cm/min blinding test 2. Bone static spot scan-regional view 200 kcts, 400 kcts for chest, pelvis, foot blinding test 3. 4 quadrant-bar phantom-20000 kcts visual evaluation 4. LSF-FWHM resolution comparison ananysis. Results: 1. Raw data (20 cm/min) & processing data (30 cm/min)-similar level image quality 2. Low count static image-image quality clearly improved at visual evaluation result. 3. Visual evaluation by quadrant bar phantom-rising image quality level 4. Resolution comparison evaluation (FWHM)-same difference from resolution comparison evaluation Conclusion: The study which applies a new method Onco. flash processing reconstruction, it will be able to confirm the image quality improvement which until high level is clearer the case which applies the method of existing better than. The new reconstruction improves the resolution & reduces the noise. This enhances the diagnostic capabilities of such imagery for radiologists and physicians and allows a reduction in radiation dosage for the same image quality. Like this fact, rising of equipment availability & shortening the patient waiting move & from viewpoint of the active defense against radiation currently becomes feed with the fact that it will be the useful result propriety which is sufficient in clinical NM.