• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.08a
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• pp.201-204
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• 2000

본 논문에서는 기존의 칼라 항상성(color constancy) 알고리즘을 기반으로 한 새로운 영상 복원 방법을 제안한다. 이 방법은 인간의 시각 특성을 선형 모델로 표현한 칼라 항상성 모델을 이용한다. 칼라 항상성 모델에서 가장 중요한 과정은 영상의 광원을 추정하는 것이다. 이론 위하여 영상에서 명도 값이 가장 큰 화소의 값을 이용하며, 이 값을 각 수광체(photoreceptor)의 응답으로 대체한다. 추정된 광원을 이용하여 만들어진 영상을 일정한 비율로 스케일링하여 영상을 복원한다. 실험을 통하여 제안한 항법으로 영상 복원이 잘 됨을 알 수 있었다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1996.06a
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• pp.181-185
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• 1996

Color image is largely corrupted by various ambient illumination. However, human perceives always white color as white under any illumination because of a characteristic of human vision, called color constancy. In the conventional algorithm which applied the constancy effect, after the RGB color space is transformed to the IHS(Intensity, Hue, and Saturation) color space, then the hue is preserved and the intensity or the saturation is properly enhanced. Then the enhanced IHS color is reversely transformed to the RGB color space. In this process, the color distortion is included due to the color gamut error. But in the proposed algorithm, there is not transformation. In that, the RGB color is considered as 3 dimensional color vector and we assume that white color is the natural daylight. As the color vector of the illumination can be calculated as the average vector of R, G, and B image, we can achieve the constancy effect by simply rotating the illumination vector to the white color vector. The simulation results show the efficiency of the vector rotating process for color image enhancement.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.5
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• pp.103-108
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• 1993

An image can be largely corrupted by the ambient illuminant, so that the image enhancement to restory natural color without respect to the ambient illuminant is needed. It this paper, a new color image enhancement technique based on color constancy is proposed. To enhance the image quality, higher volues of contrast and saturation are preferred, but their excessive values make an image unnatural. Since the color constancy processing preserves only hue, while reducing the dynamic range of lightness and saturation,the technique is needed in order to compensate this phenomenon. The proposed method transforms and increases lightness and saturation simultaneously to avoid the complexity in the related transformation by analyzing the relationship between the RGB and modified IHS coordinate system.

• 프린팅코리아
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• v.7 no.9
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• pp.113-113
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• 2008

PPC 서버는 CIP3/4에 따른 프리프레스장비에 의해 생성된 미리보기 이미지를 통하여 회선율을 산출 및 인쇄조건 데이터를 변환하여 IPC로 전송하고 전송된 데이터는 IPC를 통해 인쇄기에 잉크키 등을 미리설정(프리셋)한다. 인쇄되는 인쇄물의 잉크 키 데이터와 화선율의 데이터를 MCCS(색조관리장치)로 보내고 MCCS에서는 인쇄된 칼라 패치를 분광계로 계측하고, 그 결과를 화면에 표시한다. MCCS는 목표치에 대하여 계측치의 차이를 기준으로 목표치에 가깝게 되도록 잉크키 개도를 조절해 피드백하며, IPC EXPERT 기능용 계측 데이터를 IPC로 보낸다. 따라서, 사람의 눈으로 관리하는 컬러매니지먼트(CMS가 아닌 CIP3/4 데이터의 화선율과 인쇄조건을 PPC서버가 변환하여 IPC에 전송하는 것이다. 인쇄한 인쇄결과물을 MCCS로 계측하여 항상 기준목표 농도치에 맞게 기계에 피드백하고 잉크키 개도를 조절, 색조관리를 함으로써 일정한 품질유지 및 농도관리를 가능(손지절감 및 색조관리의 일관성)하게 하는 시스템이다.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.5
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• pp.251-258
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• 2004

This paper proposes a method for estimating the illuminant chromaticity using the distributions of the camera responses obtained by a CCD camera in a real-world scene. Illuminant estimation using a highlight method is based on the geometric relation between a body and its surface reflection. In general, the pixels in a highlight region are affected by an illuminant geometric difference, camera quantization errors, and the non-uniformity of the CCD sensor. As such, this leads to inaccurate results if an illuminant is estimated using the pixels of a CCD camera without any preprocessing. Accordingly, to solve this problem the proposed method analyzes the distribution of the CCD camera responses and selects pixels using the Mahalanobis distance in highlight regions. The use of the Mahalanobis distance based on the camera responses enables the adaptive selection of valid pixels among the pixels distributed in the highlight regions. Lines are then determined based on the selected pixels with r-g chromaticity coordinates using a principal component analysis(PCA). Thereafter, the illuminant chromaticity is estimated based on the intersection points of the lines. Experimental results using the proposed method demonstrated a reduced estimation error compared with the conventional method.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.4 s.316
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• pp.35-43
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• 2007

With the current trend of digital convergence in mobile phone, imaging devices such as cameras, displays and beam-projectors have been made smaller and become into mobile phones. Especially, built-in beam-projectors (we call it mobile beam-projector hereafter) have been developed to overcome small screen size of mobile display and to provide the realistic image while watching movies or broadcasting. However, mobile beam-projector can project an original image on various colored-screen, different from general data projector with white screen, thereby degrading the image quality of projected images. Therefore, this paper proposed a method of correcting projected images on colored-screens by adapting color constancy theory that has been mainly used for illumination estimation.