• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.5
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• pp.513-521
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• 2002

This paper proposes a gamut mapping algorithm based on color space division for cross media color reproduction. As each color device has a limited range of producible colors, reproduced colors on a destination device are different from those of the original device. In order to reduce the color difference, the proposed method divides the whole gamut into parabolic shapes based on intersecting lightness by the just noticeable difference (JND) and the original device gamut boundary. Dividing the gamut with parabolic shapes and piecewise mapping of each region not only considers gamut characteristics but also provides for mapping uniformity. Also the lightness variations are more sensitive to the human visual system and by using lightness JND it can restrict lightness mapping variations that are unperceivable to enhance lightness contrast and chrominance. As a result, the proposed algorithm is able to reproduce high quality images using low-cost color devices.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.3
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• pp.310-315
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• 2004

Image taken in the night can be low-contrast images because of poor environment and image transmission. We propose an algorithm that improves the acquired low-contrast image. MPEG-2 separates chrominance and illuminance, and compresses respectively because human vision is more sensitive to luminance. We extracted illumination and used K-means algorithm to find a proper crossover point automatically. We used K-means algorithm in the viewpoint that the problem of crossover point selection can be considered as the two-category classification problem. We divided an image into two subimages using the crossover point, and applied the histogram equalization method respectively. We used the index of fuzziness to evaluate the degree of improvement. We compare the results of the proposed method with those of other methods.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.11
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• pp.1946-1953
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• 2006

Because the embedded watermark of luminance component guarantees the extraction of ownership information when the color image is converted to gray scale image, the information of ownership right as to the luminance component is embedded in the luminance-chrominance color space such as YCbCr. Therefore, this paper proposes watermark embedding, extraction and authentication algorithm of color image. which considers the device and performance of multimedia contents service by focusing on the robustness and invisibility of watermark. The color image is converted from RGB color space to YCbCr color space, and then the properties of each component of Y(Luminance), Cb(Color Differences) and Cr(Color Differences) are considered in order to embed, extract and certify multi-level watermark in the frequency domain based on the wavelet. As a result, it can guaranteed the robustness for the JPEG compression and invisibility of watermark for multi-level.

• Journal of Broadcast Engineering
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• v.27 no.5
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• pp.812-815
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• 2022

Images displayed on a digital devices under the sunlight are generally perceived to be darker than the original images, which leads to a decrease in visibility. For better visibility, global luminance compensation or tone mapping adaptive to ambient lighting is required. However, the existing methods have limitations in chrominance compensation and are difficult to use in real world due to their heavy computational cost. To solve these problems, this paper propose a piece-wise linear curves (PLECs)-based image enhancement method to improve both luminance and chrominance. At this time, PLECs are regressed through deep learning and implemented in the form of a lookup table to real-time operation. Experimental results show that the proposed method has better visibility compared to the original image with low computational cost.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.12
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• pp.73-86
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• 1993

This paper proposes an automatic variable block truncation coding (BTC) method. It selects the block size automatically based on the mode of the discontinutiy measure of blocks. The combination of an automatic block-size determination scheme and the conventional BTC results in the proposed automatic variable BTC techniques. For color images, subsampling in I and Q chrominance components is adopted along with the variable BTC. To show the effectiveness of the proposed algorithm, its simulation results are compared to those of the several conventional BTC algorithms for monochrome and color test images. Computer simulation shows that the proposed algorithm gives better performance than the conventional ones based on the subjective and objective performance evaluation.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.371-374
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• 2005

A novel Color Image Saturation enhancement method to strengthen video images without producing oversaturated or color contour artifacts is proposed in this paper. Based on the luminance information, the relations between luminance levels and maximum chrominance vectors in each subcolor are generated for each pixel, so that the upper bound of the allowed saturation factor for a pixel can be derived, and much vivid video image can be achieved

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.677-680
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• 2001

본 논문에서는 컬러 장치들간에 색을 일치시키기 위하여 휘도 대비와 채도 향상을 고려한 원형 색역 사상(circular shape-based gamut mapping)방법을 제안하였다. 서로 다른 장치들간에 색역을 일치시키기 위해 장치 독립적이고 균등 색 공간인 CIELAB값으로 변환하여 색역 사상을 수행하였다. 인간 시각에 상대적으로 민감한 특성을 가지는 휘도 성분을 JND(just noticeable difference)에 기반해 분할하고, 이를 기점으로 색역을 원의 형태로 나눈다. 이렇게 나뉜 색역은 사상의 방향성을 결정하는 기본 단위로 사용되어, 이들 영역을 기점으로 영역 대 영역별 사상 방법을 사용하였다. 제안한 색역 사상 방법을 모니터와 프린터간에 적용한 결과 보다 선명하고 휘도 대비가 높은 영상을 얻을 수 있었다.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.725-728
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• 2000

본 논문에서는 영상검색 기법에서 핵심인 Shot Change Detection 과 Non Linear Browsing 을 H/W기반으로 구현하여, S/W 적으로는 비실시간으로만 가능하였던 video indexing 을 DTV 에 적용하여 실시간으로 구현하는 방법을 제시한다. 이를 위해 H/W part 는 실시간으로 들어오는 방송용 MPEG-2 bitstream 을 full decoding 이 아닌 최소화된 VLD(Variable Length Decoding) 수준의 parsing 으로 picture 내의 luminance와 chrominance 의 DC 값, macroblock type, motion vector 정보를 얻어내어 각각의 histogram을 계산하여 memory interface를 통해 S/W 측에 넘겨주게 되고 S/W 는 각 상황에 맞게 indexing algorithm 을 변화시키며 최적의 video indexing 방법으로 확장할 수 있도록 하였다.

• Journal of Sensor Science and Technology
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• v.29 no.2
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• pp.133-140
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• 2020

This study proposes a method of blending visible and near infrared images to enhance edge details and local contrast. The proposed method consists of radiance map generation and color compensation. The radiance map is produced by a Laplacian pyramid and a soft mixing method based on principal component analysis. The color compensation method uses the ratio between the composed radiance map and the luminance channel of a visible image to preserve the visible image chrominance. The proposed method has better edge details compared to a conventional visible and NIR image blending method.

• Journal of Korea Multimedia Society
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• v.4 no.1
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• pp.67-74
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• 2001

In this paper, we propose a face detection algorithm using the color and shape information in color still images. The proposed algorithm is only applied to chrominance components(Cb and Cr) in order to reduce the variations of lighting condition in YCbCr color space. Input image is segmented by pixels with skin-tone color and then the segmented mage follows the morphological filtering an geometric correction to eliminate noise and simplify the segmented regions in facial candidate regions. Multiple facial regions in input images can be isolated by connected component labeling. Moreover tilting facial regions can be detected by extraction of second moment-based ellipse features.