• 대한방사선기술학회지:방사선기술과학
• /
• 제45권1호
• /
• pp.1-9
• /
• 2022

In this study, we proposed an image quality control for an automatic exposure control (AEC) of digital radiographic imaging system and tried to analyze the performance of the AEC by various manufacturer. The subjects of the experiment were analyzed for the AEC image quality evaluation using digital radiation generators from four manufacturer such as PHILIPS, GE Healthcare, SAMSUNG Healthcare, DK Medical Solution. We used as materials for the implementation of the image quality evaluation by coins (500 won, KOMSCO, Korea). This study evaluated the performance evaluation of the AEC as image quality and exposure dose (Milliampere-seconds; mAs). The image quality evaluation was tried visual assessment by two radiologic technologists and contrast to noise (CNR) by ImageJ. The exposure dose investigated mAs on digital radiation generators. The radiographic coin images acquired 360 images based on change in the control factors of the AEC, which were kVp, the consistency of field configuration and dominant zone, sensitivity and density. As a result, there was a significant difference in the AEC performance between manufacturer. The CNR by the AEC for each manufacturer showed a difference of up to about 1.9 times. The exposed tube current by the AEC for each manufacturer showed a difference of up to about 5.8 times. It is expected that our proposed evaluation method using coins could be applied as the AEC performance evaluation method in the future.

• 대한전자공학회논문지
• /
• 제25권4호
• /
• pp.447-452
• /
• 1988

This paper proposes a hybrid image coding in order to improve the coding performance by combining the BTC with the DPCM. And utilizing the human perceptual characteristics, a new objective image quality evaluation method has been proposed to obtain an excellent result in good agreement with the subjective quality evaluation. A hyb-1 method consisting of the DPCM and the AMBTC has retained a good picture quality at the bit rate of 1.5 bits/pel. A hyb-3 method combining the EBTC-3 with the DPCM has scarcely degraded the picture quality compared with the original image at the bit rate of 2.1 bits/pel. A newly proposed mehtod of picture quality evaluation accumulating a blocky noise at the edge block and an impulsive noise at the flat block selectively has been coincident with the subjective evaluation of quality.

• Nuclear Engineering and Technology
• /
• 제54권9호
• /
• pp.3380-3389
• /
• 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.

• 정보처리학회논문지:소프트웨어 및 데이터공학
• /
• 제4권12호
• /
• pp.571-576
• /
• 2015

다양한 안개 제거 기술이 개발되어왔으나 이들의 성능을 정량 정성적으로 평가하는 방식에 대한 연구는 다소 부족하다. 본 논문에서는 안개 제거 기술의 성능을 평가하기 위하여 사용할 수 있는 다양한 척도를 살펴본다. 성능 척도의 신뢰도 검증을 위하여, 고화질 칼라 깊이 영상을 이용하여 안개 영상을 합성하고 안개 제거 영상과 원 영상을 비교하는 방식을 택한다. 한편 안개 제거 기술을 화질을 기준으로 평가하는 방식이 아닌, 안개 제거 전 후 영상에 대한 컴퓨터 비전 기법의 성능을 비교하는 방식을 검토한다. 다양한 안개 제거 기술 성능 척도에 대한 비교 분석 및 문제점에 대한 해결 방안을 토의한다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제9권9호
• /
• pp.3672-3684
• /
• 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.

• 한국방송∙미디어공학회:학술대회논문집
• /
• 한국방송공학회 2009년도 IWAIT
• /
• pp.76-79
• /
• 2009

This paper investigates the performance of a vehicular rear-view camera through quantifying the image quality based on several objective criteria from the ISO (International Organization for Standardization). In addition, various experimental environments are defined considering the conditions under which a rear-view camera may need to operate. The process for evaluating the performance of a rear-view camera is composed of five objective criteria: noise test, resolution test, OECF (opto-electronic conversion function) test, color characterization test, and pincushion and barrel distortion tests. The proposed image quality quantification method then expresses the results of each test as a single value, allowing easy evaluation. In experiments, the performance evaluation results are analyzed and compared with those for a regular digital camera.

• 융합신호처리학회논문지
• /
• 제17권1호
• /
• pp.26-31
• /
• 2016

본 논문에서는 소형 카메라 모듈의 화질을 분석하는 시스템을 제안하고 이를 이용하여 렌즈의 성능을 평가하며, 플레어 및 헐레이션 방지 디스크를 삽입하여 렌즈의 성능이 개선되는 효과를 검증한다. 카메라 모듈의 화질을 평가하는 카메라 모듈 화질검증 시스템과 이미지 신호 처리기(Image Signal Processor, ISP) 내부의 레지스터를 제어하는 카메라 모듈 제어 프로그램 및 화질분석 소프트웨어를 개발한다. 제안된 헐레이션 방지 디스크를 삽입된 카메라 모듈의 화질을 기존 카메라 모듈의 화질과 비교평가에서 획득된 영상의 해상도, 밝기, 색재현 등의 성능을 검증한다.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2008년도 하계종합학술대회
• /
• pp.855-856
• /
• 2008

In this paper, we studied the performance evaluation of a vehicular rear-view camera through quantifying the image quality based on several objective criteria from the ISO (International Organization for Standardization). In addition, various experimental environments are defined considering the conditions under which a rear-view camera may need to operate. The process for evaluating the performance of a rear-view camera is composed of five objective criteria: noise test, resolution test, OECF (opto-electronic conversion function) test, color characterization test, and pincushion and barrel distortion tests. The proposed image quality quantification method then expresses the results of each test as a single value, allowing easy evaluation.

• 한국멀티미디어학회논문지
• /
• 제20권11호
• /
• pp.1741-1749
• /
• 2017

In commercial digital-cameras, color-filter filters light according to wavelength range of color filter array (CFA) and the filtered intensities contain color information of light. Then, output data of CFA is transformed to final rendered image through demosaicing process. In image processing of digital-camera, the quality of the final rendered image is affected by optical cross talk of CFA, kind of CFA pattern etc. Basically, pattern of CFA plays important role in image quality of final image rendered by digital-camera. Therefore, an evaluation system capable of quantitatively evaluating CFA is needed. This paper proposes a novel evaluation system using existing and proposed image metrics for evaluating CFAs of digital-camera. Proposed CFA evaluation system consist of color difference in CIELAB and S-CIELAB, Structure SImilarity (SSIM), MTF50, moire starting point (MSP), and subjective preference (SP). MSP and SP are newly designed for the proposed evaluation system. Proposed evaluation system is expressed in polar coordinates to analyze the characteristics of CFA objectively and intuitively. Through simulations, we confirmed that proposed CFA evaluation system can objectively assess performance of developed CFAs.

• International Journal of Computer Science & Network Security
• /
• 제24권1호
• /
• pp.163-177
• /
• 2024

The fingerprint image quality relies on the clearness of separated ridges by valleys and the uniformity of the separation. The condition of skin still dominate the overall quality of the fingerprint. However, the identification performance of such system is very sensitive to the quality of the captured fingerprint image. Fingerprint image quality analysis and enhancement are useful in improving the performance of fingerprint identification systems. A fuzzy technique is introduced in this paper for both fingerprint image quality analysis and enhancement. First, the quality analysis is performed by extracting four features from a fingerprint image which are the local clarity score (LCS), global clarity score (GCS), ridge_valley thickness ratio (RVTR), and the Global Contrast Factor (GCF). A fuzzy logic technique that uses Mamdani fuzzy rule model is designed. The fuzzy inference system is able to analyse and determinate the fingerprint image type (oily, dry or neutral) based on the extracted feature values and the fuzzy inference rules. The percentages of the test fuzzy inference system for each type is as follow: For dry fingerprint the percentage is 81.33, for oily the percentage is 54.75, and for neutral the percentage is 68.48. Secondly, a fuzzy morphology is applied to enhance the dry and oily fingerprint images. The fuzzy morphology method improves the quality of a fingerprint image, thus improving the performance of the fingerprint identification system significantly. All experimental work which was done for both quality analysis and image enhancement was done using the DB_ITS_2009 database which is a private database collected by the department of electrical engineering, institute of technology Sepuluh Nopember Surabaya, Indonesia. The performance evaluation was done using the Feature Similarity index (FSIM). Where the FSIM is an image quality assessment (IQA) metric, which uses computational models to measure the image quality consistently with subjective evaluations. The new proposed system outperformed the classical system by 900% for the dry fingerprint images and 14% for the oily fingerprint images.