• Proceedings of the Korea Information Processing Society Conference
• /
• 2007.05a
• /
• pp.326-327
• /
• 2007

We investigated whether the CT images of hepatic lesions could be analyzed by computer-aided diagnosis (CAD) tool. We retrospectively reanalyzed 14 liver CT images (10 hepatocellular cancers and 4 benign liver lesions; patients who presented with hepatic masses). The hepatic lesions on CT were segmented by rectangular ROI technique and the morphologic features were extracted and quantitated using fractal texture analysis. The contrast enhancement of hepatic lesions was also quantified and added to the differential diagnosis. The best discriminating function combining the textural features and the values of contrast enhancement of the lesions was created using linear discriminant analysis. Textural feature analysis showed moderate accuracy in the differential diagnosis of hepatic lesions, but statistically insignificant. Combining textural analysis and contrast enhancement value resulted in improved diagnostic accuracy, but further studies are needed.

• 전자공학회논문지 IE
• /
• v.46 no.4
• /
• pp.31-41
• /
• 2009

The Image sensor of digital still camera has a limited dynamic range. In high dynamic range scenes, a picture often turns out to be underexposed or overexposed. Retinex algorithm based on the theory of the human visual perception is known to be effective contrast enhancement technique. However, it happens the unbalanced contrast enhancement which is the global contrast increased, and the local contrast decreased in the high dynamic range scenes. In this paper, to enhance the both global and local contrast, we propose the weight mapping retinex algorithm. Weight map is composed of the edge and exposure data which are extracted in the each retinex image, and merged with the retinex images in the fusion processing. According to the output picture comparing and numerical analysis, the proposed algorithm gives the better output image with the increased global and local contrast.

• MALSORI
• /
• no.56
• /
• pp.1-13
• /
• 2005

This study examined the speech intelligibility of one-syllable words with phonetic contrasts and analyzed segmental factors that can predict the overall speech intelligibility in hearing-impaired adults. To identify the speech error characteristics, a Korean word list was audio-recorded by 7 hearing-impaired adults, and 35 listeners selected the heard word out of 5 choices. Based in part on previous studies of speech of the hearing impaired, the word list consisted of monosyllabic consonant-vowel-consonant (CVC) real word pairs. Stimulus words included 77 phonetic contrast pairs. The results showed that the percentage of errors in final position (coda) contrast was higher than in any other position in syllable. And the intelligibility deficit factors of phonetic contrast in the hearing-impaired were analyzed through stepwise regression analysis. The overall intelligibility was predicted by the error rate of manner contrast at coda, voicing contrast (homorganic triplets) at onset and high-low contrast at nucleus.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.12 no.7
• /
• pp.3401-3420
• /
• 2018

Pixel expansion and contrast are two major performance parameters for visual cryptography scheme (VCS), which is a type of secret image sharing. Random Grid (RG) is an alternative approach to solve the pixel expansion problem. Chen and Tsao proposed the first (k, n) RG-based VCS, and then Guo et al., Wu et al., Shyu, and Yan et al. significantly improved the contrast in recent years. However, the investigations on improving the contrast of threshold RG-based VCS are not sufficient. In this paper, we develop a contrast-improved algorithm for (k, n) RG-based VCS. Theoretical analysis and experimental results demonstrate that the proposed algorithm outperformers the previous threshold algorithms with better visual quality and a higher accuracy of contrast.

• Journal of Magnetics
• /
• v.21 no.2
• /
• pp.281-285
• /
• 2016

The purpose of study was to evaluate SNR and CNR with different contrast agent contents (1.0 mmol/mL gadobutrol and 0.5 mmol/mL gadoterate meglumine) for spin echo (SE) and 3-dimension contrast-enhanced fast field echo (3D CE-FFE) pulse sequences. In this study, we compared the SNR and the CNR between 0.5 mmol/mL gadoterate meglumine and 1.0 mmol/mL gadobutrol according to the concentration of contrast agent in brain MRI. When we compared between SE and 3D CE-FFE pulse sequences, the higher SNR and CNR using 3D CE-FFE pulse sequence can be acquire regardless of contrast agent contents. Also, a statistically significant difference was found for SNR and CNR between all protocols. In conclusion, our results demonstrated that the SNR and CNR have not risen proportionately with contrast agent contents. We hope that these results presented in this paper will contribute to decide contrast agent contents for brain MRI.

• Journal of radiological science and technology
• /
• v.44 no.4
• /
• pp.335-342
• /
• 2021

Studies on the side effects of contrast agents are being discussed based on various cases, but studies analyzing the chemical structure of the underlying contrast agents are difficult to understand as the manufacturers have not disclosed them. Therefore, in this study, the chemical structure of the contrast medium was analyzed using ¹H-NMR spectrometer for Omnipaque contrast medium prepared from Iohexol, which is a nonionic iodide contrast medium, Xenetix contrast medium from Iobitridol, and Iomeron contrast medium from Iomeprol. As a result, it was found that the Omnipaque contrast medium of Iohexol had 6 carboxyl groups, 3 carbonyl groups, 4 amine groups, 1 methyl group, and 2 cyano groups. It was found that the Xenetix contrast medium of the iobitridol formulation had 6 carboxyl groups, 3 carbonyl groups, 2 amine groups, and 4 cyano groups. It was found that the Iomeron contrast agent of the Iomeprol formulation had 5 carboxyl groups, 3 carbonyl groups, 4 amine groups, 1 methyl group, and 2 cyano groups. As shown in this study, the chemical structure of the non-ionic monomer contrast agent increases its affinity with water by binding a number of hydroxyl groups (OH) to the carboxyl group. It is necessary to accurately identify each of these factors and analyze the physical and chemical changes of the contrast medium according to various environmental factors.

• Proceedings of the IEEK Conference
• /
• 2007.07a
• /
• pp.361-362
• /
• 2007

We propose a contrast-controlled feature detection approach for steel radiograph image. X-ray images are low contrast, dark and high noise image. So, It is not simple to detect defects directly in automated radiography inspection system. Contrast enhancement, histogram equalization and median filter are the most frequently used techniques to enhance the X-ray images. In this paper, the adaptive control method based on contrast limited histogram equalization is compared with several histogram techniques. Through comparative analysis, CLAHE(contrast controlled adaptive histogram equalization) can enhance detection of defects better.

• Journal of Information Technology Applications and Management
• /
• v.25 no.2
• /
• pp.41-52
• /
• 2018

This paper presents a method for accurate camera self-calibration based on SIFT Feature Detection and image quality assessment. We performed image quality assessment to select high quality images for the camera self-calibration process. We defined high quality images as those that contain little or no blur, and have maximum contrast among images captured within a short period. The image quality assessment includes blur detection and contrast assessment. Blur detection is based on the statistical analysis of energy and standard deviation of high frequency components of the images using Discrete Cosine Transform. Contrast assessment is based on contrast measurement and selection of the high contrast images among some images captured in a short period. Experimental results show little or no distortion in the perspective view of the images. Thus, the suggested method achieves camera self-calibration accuracy of approximately 93%.

• Journal of the Korea Fashion and Costume Design Association
• /
• v.12 no.1
• /
• pp.117-130
• /
• 2010

The main objective of this research was to understand the characteristics of contrast color coordination through the analysis of modern woman fashion color coordination as they appear in the 'Collections' from '04 SS to '09/'10 AW. Data collection of 122 was done through review of '$pr{\hat{e}}t$-$\grave{a}$-porter Collections' of four cities; Milan, London, New York, Paris. Statistical analysis of frequency and qualitative interpretation of contrast color coordination characteristics were completed. The main findings were as follows; (1) The combined color type of 'red+blue' and 'yellow+blue' were the most frequently appeared in the same ratio, and followed by 'green+violet', 'red+yellow', 'green+orange', and 'orange+violet'. The contrast tone showed the most, and followed by the similarity and identity, and the type of tone harmony used differently according to the type of contrasting color combination. (2) The general characteristics of contrasting color harmony were as follows,; Some contrasting colors looked harmonious when used light colors and the contrast between light and dull colors which made the hues even more harmonious. Also combinations of dull colors which work well with other dull colors or vivid colors. Light & vivid color or light & dark color, however, often showed too much contrast and using two contrasting vivid colors presented awkward and restless look. When used one vivid color and one dark color, a little easier to looked at, but still not particularly elegance or effectively harmonious. (3) The types of contrasting color harmony showed some differences between seasons. Contrasting color harmony showed more frequently in the S/S collections than in A/W collections.

• The Korean Journal of Pain
• /
• v.21 no.3
• /
• pp.217-223
• /
• 2008

Background: Lumbar transforaminal epidural injections (LTEIs) have been utilized in the treatment of radicular pain, and LTEIs have the advantage of target-specificity. However, there have not been enough studies on the contrast patterns in LTEIs with using fluoroscopy. The purpose of this study was to evaluate the spreading epidural contrast patterns that are seen during real-time fluoroscopic guided LTEIs. Methods: A total of 131 patients who underwent fluoroscopic guided LTEIs were studied. The inclusion criteria were those patients with low back pain and/or lower extremity pain that was caused by a herniated nucleus pulposus, lumbar spinal stenosis, failed back surgery syndrome, and herpes zoster-associated pain. We classified the contrast patterns in regard to the contrast flow spreading to the nerve root and/or the unilateral, bilateral or cylinderic type of epidural spreading on the AP view of the fluoroscopy and the ventral or dorsal epidural filling on the lateral view. In addition to the pattern analysis, we evaluated the range of contrast spreading from the cranial to the caudal epidural filling and the incidence of an intravascular flow pattern. Results: Epidural spreading was seen in 126 cases (96.2%) of the total patients through the nerve root. Ventral spreading occurred in 120 cases (95.2%). On the AP view, a nerve root with unilateral, bilateral and cylinderic epidural filling was noted for 108 (85.7%), 9 (7.1%) and 9 (7.1%) cases, respectively. The contrast spreading to vertebral segments was smaller for the patients with lumbar spinal stenosis and failed back surgery syndrome than for the other groups (P < 0.0083). The incidence of intravascular injection was 11.1% (14/126). Conclusions: LTEIs using fluoroscopic visualization provided excellent assessment of the ventral epidural filling as well as nerve root filling. However, unilateral epidural spreading was prominent for the LTEIs.