• Journal of the Korea Society of Computer and Information
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• v.19 no.5
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• pp.19-25
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• 2014

In this paper, I seek the chromatic number, the maximum number of colors necessary when adjoining vertices in the plane separated apart at the distance of 1 shall receive distinct colors. The upper limit of the chromatic number has been widely accepted as $4{\leq}{\chi}(G){\leq}7$ to which Hadwiger-Nelson proposed ${\chi}(G){\leq}7$ and Soifer ${\chi}(G){\leq}9$ I firstly propose an algorithm that obtains the minimum necessary chromatic number and show that ${\chi}(G)=3$ is attainable by determining the chromatic number for Hadwiger-Nelson's hexagonal graph. The proposed algorithm obtains a chromatic number of ${\chi}(G)=4$ assuming a Hadwiger-Nelson's hexagonal graph of 12 adjoining vertices, and again ${\chi}(G)=4$ for Soifer's square graph of 8 adjoining vertices. assert. Based on the results as such that this algorithm suggests the maximum chromatic number of a planar graph is ${\chi}(G)=4$ using simple assigned rule of polynomial time complexity to color for a vertex with minimum degree.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.01a
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• pp.21-22
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• 2020

본 논문에서는 자동채색 머신러닝 모델을 모바일에서 사용하기 위해 효율적으로 힌트 입력하기 위한 방법을 제시한다. 기존의 자동채색 기법은 서버-클라이언트 채색 방식으로 인터넷에 연결되어 있어야만 채식이 된다는 문제가 있다. 이를 보완하여 네트워크 연결 없이 모바일에서 사용할 수 있는 머신러닝과 이를 사용하기 위해 입력으로 넣어야 하는 힌트 및 이미지를 효율적으로 나눌 수 있는 방법을 고안한다.

• Korean Journal of Mineralogy and Petrology
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• v.36 no.1
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• pp.1-17
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• 2023

On painting cultural properties to which Orpiment, a traditional yellow mineral pigment, is applied, the color's degeneration is frequently observed. To identify the cause of the degeneration, this study takes a look into orpiment and the various pigments that are mixed into it (Lead White, Lead Red, and Cinnabar) in powder and painting state. The pigment was mixed with Argyo glue and then applied to korean traditional paper and silk. Considering the possibility that alum causes the discoloration, it was applied to the specimen. With a UV tester, the powders and the painted specimens were subjected to a light resistance test in three phases (96 hour). Color changes were measured with a colorimeter and minerals, chemical composition and structural changes were analysed by XRD, SEM/EDS and Raman spectrometers. While the color change of pure Orpiment powder according to the light resistance test was small, the colored specimen became darker. The color change was large in the Orpiment colored on the silk and in the alum-treated specimen. In Orpiment powder was produced white arsenolite as altered orpiment after UV test. In the mixed powder of Orpiment and Lead White were detected only the constituent minerals of Orpiment and Lead White, and no altered substances were produced. Whereas after the UV test, orpiment and arsenolite, which were altered substances of orpiment, and the constituent minerals of Lead White were detected. In the case of mixing the two pigments in the powder state, darkening did not occur even by the UV test. However, the specimens colored with the mixed powder were darkened by the UV test. The color change of Orpiment was different depending on the mixed pigment and base material. The color change was greater in the case of alum treatment than in the case without alum treatment, and it was found that alum also had an influence on the color change of Orpiment.

• Korean Journal of Heritage: History & Science
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• v.46 no.3
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• pp.150-171
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• 2013

The most important part of conservation treatment of murals is to preserve them against the risk of a damage by injecting fixative into them when the painting loses its cohesion or powderization of pigments occurred due to occurrence of cracks inside the painting layer. However, studies on the stability of fixative used for painting layers of murals are still insufficient. This study manufactured a mural as a specimen and colored it with four kinds of pigments including oyster shell white, cinnabar, malachite and red clay and applied four kinds of fixative, including, Paraloid $B-72^{(R)}$, Caparol-$binder^{(R)}$, glue and Hydoxypropyl $cellulose^{(R)}$. artificially generated environmental changes in temperature, humidity and ultraviolet rays which may occur after the completion of conservation treatment. Then the changes in physical properties were observed in multifaceted ways such as color stability, contact angle, brilliance, adhesive strength and surface. As a result, this study found that ultraviolet rays and hot?humid environment have a large impact on color stability causing changes in brightness and chroma of all painting layers where the fixative were applied, except for oyster shell white and are considered the main factors of decomposition by accelerating the aging process of fixatives applied. In comparison to the synthetic resins that were also tested in this study, the traditional glue showed satisfactory results in terms of color stability and influence preservation and the hydrophile property. As it showed exceptionally outstanding adhesive strength in all painting layers in the aspect of adhesive strength, it is considered to be highly stabile for the fixation treatment of painting layers of mural.

• Journal of Conservation Science
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• v.35 no.5
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• pp.416-429
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• 2019

Bongchae is primarily employed for toning, which is the last step in the conservation treatment of paper's cultural properties. The objective of this study is to identify the coloring patterns of four types of Bongchae(Bonram, Gamboge, Yeonji, and Daeja) and determine the associated color change patterns through accelerated aging experiments. By examining the coloring patterns, it is observed that Yeonji, Bonram, and Daeja are painted as particles, whereas Gamboge indicates a close state of coating. Results obtained from X-ray diffraction analysis of Bongchae indicate that the presence of quartz, calcite, and pyrophyllite can be equally detected in Bonram, Yeonji, and Daeja. Additionally, the presence of goethite is also detected in Daeja. Gamboge becomes discolored from yellow to orange color during wet thermal aging, and Gamboge and Yeonji become decolorized during UV irradiation aging. Hence, cultural properties of paper colored with Gamboge can be predicted to become discolored to orange color by alkalis and can be darkened by UV rays because the decolorization of Gamboge and Yeonji occurs preferentially.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.3
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• pp.11-11
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• 2001

일반적 칼라 출력 장치는 제한된 범위의 색만을 재현 할 수 있다. 특히 프린터와 같이 색의 재현성이 부족한 장비에서는 하드웨어 특성에 따른 채색 면적이나 인쇄에 사용되는 용지의 특성에 따라 염료의 확산 등에 대해서도 고려해야 한다. 특히, 색을 프린트하기 위해서는 출력 과정에서 색의 선형적인 증가와 감소가 이루어져야 하며 또한 정확한 색의 모델링이 가능하여야 한다. 따라서 본 논문에서는 이를 위해 프린터 출력시 실제 채색 면적과 시각적 색감을 고려할 수 있는 디더링 방법을 제안한다. 제안된 방법은 실제 채색 면적을 고려한 패턴 데이터 베이스를 만들어 이를 디더링 패턴으로 이용하게 된다. 그리고 이 데이터 베이스에서 정확한 패턴을 선택하기 위해서는 인간시각의 색 인지력을 모델링한 대조 민감도 함수를 사용하게 된다. 따라서 본 논문에서는 저해상도의 칼라 출력장치에서도 고화질의 색을 재현할 수 있게 해준다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2008.11a
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• pp.207-210
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• 2008

채색화는 흑백 영상에 색 정보를 추가하거나 영상의 색을 변환하는 영상 개선 기법이다. 본 연구는 최소한의 사용자 개입을 통해 흑백 영상을 자연스러운 칼라 (color) 영상으로 전환하는 채색화 기법을 제안한다. 우리는 우선 자연스러운 채색 결과를 위한 채색화 함수를 정의한다. 제안하는 채색화 함수는 유사한 밝기 정보를 가지는 이웃 픽셀들은 비슷한 색 정보를 가질 확률이 높다는 간단한 가정 하에 MRF (Markov Random Field)에 기반하여 모델링한다. 채색화 함수에 의해 색이 전체적으로 자연스럽게 분포될 수 있도록, 확산 신뢰도를 정의한 후 신뢰도에 따라 채색 순서를 결정한다. 이후, 채색 순서에 따라 각 픽셀에 채색화 함수를 적용하여 자연스러운 채색 결과를 도출한다. 실험 결과에서 보듯이, 제안 기법은 적은 색상 정보의 입력을 통해 효과적으로 채색화 하며, 기존 기법에 비해 자연스러운 결과를 제시한다.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10c
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• pp.505-509
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• 2007

색 변환(Color Transfer) 기법은 컴퓨터 비전 및 영상 처리 분야에서 점점 더 많은 연구가 되고 있는 분야이다. 이는 참조 영상의 분위기를 원본 영상에 반영하는 기법이다. 본 논문에서는 채도가 낮은 색상에서 나타나는 잘못된 연산 결과를 해결하기 위해 채도 문턱치에 따라 유채색과 무채색으로 분류하여 인덱싱 하고, Lab색 모델에서 색상 채널인 a, b를 사용하여 그림 영상에서의 색 변환하는 방법을 제안한다. 제안된 방법은 영상의 화소들의 채도 문턱치를 이용하여 유채색과 무채색으로 분류하는 단계, 분류된 화소들의 색 특성을 이용한 cylindrical metric를 이용한 인덱싱 하는 단계, 각 인덱스 내의 위치적 표준편차와 화소수를 이용하여 인덱스들의 우열을 가리는 단계, 인덱스들의 우세한 순서로 Lab 색 모델에서 a 채널과 b 채널을 이용하여 색 변환하는 단계 등 4단계로 구성된다. 실험결과는 제안한 방법이 무채색과 유채색이 잘 분류되어 인덱싱 되었음을 보이고 원본 영상의 색이 참조영상의 색으로 잘 변환된 것을 보인다.

• Journal of the Institute of Convergence Signal Processing
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• v.2 no.2
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• pp.39-46
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• 2001

In this paper we propose a new method that can be estimation the spectral power distribution of the light source from three-band images. the light source is estimated by dividing the reflected spectral power distribution of the maximum achromatic region(L(λ)) by the corresponding surface reflectance(Ο(λ)). In order to obtain reflected spectral power distribution of the maximum achromatic region from three-bend images, a modified gray world assumption algorithm is adapted. And the maximum surface reflectance is estimated using the principal component analysis method along with achromatic population. The achromatic population is created from a set of given Munsell color chips whose chroma vector is less than threshold. Cumulative contribution ratio of principal components from the first to the third for classified achromatic population was about 99.75%. The reconstruction of illumination spectral power distribution by using achromatic population and three-band digital images captured under various light source was examined, and evaluated by RMSE between the original and reconstructed illumination spectral power distribution. This work was supported by grant No (2000-1-30200-005-3) from the Basic Research Program of the Korea Science & Engineering Foundation.

• Journal of Conservation Science
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• v.32 no.1
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• pp.89-100
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• 2016

We estimated pigments and painting techniques with nondestructive analysis for Yu Eonho's portrait made in the eighteenth century, then compared with 11 portraits and painting characteristics at that time. The pigments used to Yu Eon-ho's portrait include lead white, yellow dye, cinnabar, minium, and pink dye, malachite, azurite, iron oxide red and brown dye, blue and pink dye for purple. In the result compared with painted pigments of 11 portraits, iron oxide red without cinnabar was used on the face part and organic green dye only was used instead of inorganic pigments on the other side of clothing after Yu Eonho's portraits portrait. This study is show the painting techniques on the portraits in the late $18^{th}$ century. We expect to use as useful referencing data for the study on the coloring technique of a portrait in the late Joseon Dynasty.