• Journal of the Institute of Electronics and Information Engineers
• /
• v.53 no.6
• /
• pp.110-121
• /
• 2016

The primary aim of the color constancy algorithm is to estimate illuminant chromaticity. There are various statistical-based, learning-based and combinational-based color constancy algorithms already exist. However, the statistical-based algorithms can only perform well on images that satisfy certain assumptions, learning-based methods are complex methods that require proper preprocessing and training data, and combinational-based methods depend on either pre-determined or dynamically varying weights, which are difficult to determine and prone to error. Therefore, this paper presents a new optimization based illuminant estimation method which is free from complex preprocessing and can estimate the illuminant under different environmental conditions. A strong color cast always has an odd standard deviation value in one of the RGB channels. Based on this observation, a cost function called the degree of illuminant tinge(DIT) is proposed to determine the quality of illuminant color-calibrated images. This DIT is formulated in such a way that the image scene under standard illuminant (d65) has lower DIT value compared to the same scene under different illuminant. Here, a swarm intelligence based particle swarm optimizer(PSO) is used to find the optimum illuminant of the given image that minimizes the degree of illuminant tinge. The proposed method is evaluated using real-world datasets and the experimental results validate the effectiveness of the proposed method.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.50 no.10
• /
• pp.142-149
• /
• 2013

In general, a color of an image is represented by using red, green, and blue channels in a RGB camera system. However, only information of three channels are limited to estimate a spectral reflectance of a real scene. Because of this, the RGB camera system can not accurately represent the color. To overcome this limitation and represent an accurate color, researches to estimate the spectral reflectance by using a multi-channel camera system are being actively proceeded. Recently, a reflectance estimation method adaptively constructing a similar training set from a traditional training set according to a camera response by using a spectral similarity was introduced. However, in this method, an accuracy of the similar training set is reduced because the spectral similarity based on an average and a maximum distances was applied. In this paper, a reflectance estimation method applied a spectral similarity based on a correlation coefficient is proposed to improve the accuracy of the similar training set. Firstly, the correlation coefficient between the similar training set and the spectral reflectance obtained by Wiener estimation method is calculated. Secondly, the similar training set is constructed from the traditional training set according to the correlation coefficient. Finally, Wiener estimation method applied the similar training set is performed to estimate the spectral reflectance. To evaluate a performance of the proposed method with previous methods, experimental results are compared. As a result, the proposed method showed the best performance.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.49 no.4
• /
• pp.40-48
• /
• 2012

This paper models the hue shift phenomenon and proposes a hue correction method to give perceptual matching between projector with and without additional white channel. To quantify the hue shift phenomenon for whole hue angle, 24 color patches with the same lightness are frist created along equally-spaced hue angle, and these are displayed one by one both displays with different luminance levels. Next, each hue value of the patches appeared on the projector with additional white channel is adjusted by observers until the hue values of patches on both displays appear the same visually. After obtaining the hue shift values from the color matching experiment, these values are piecewise fit into six polynomial functions, which approximately determine shifted hue amounts for an arbitrary hue values of each pixel in projector with additional white channel and are utilized to correct them. Actually, an input RGB image is converted to CIELAB LCH color space to get hue values of each pixel and this hue value is shifted as much as the amount calculated by the functions of hue shift model for correction. Finally, corrected image is inversely converted to an output RGB image. For an evaluation, the matching experiment with several test images and the z-score comparisons were performed.

• Proceedings of the Korean Information Science Society Conference
• /
• 2001.10b
• /
• pp.433-435
• /
• 2001

얼굴 인식분야에서 실시간 얼굴검출에 대한 관심이 높아짐에 따라 피부색컬러 모델을 통한 얼굴영역검출에 대한 연구가 활발히 진행되고 있다. 그러나, 기존의 피부색 모델은 밝기 정보를 제거한 단일 채널의 색상모델이 대부분이다. 이에 본 논문에서는 얼굴피부색을 보다 효과적으로 모델링하기 위하여, 피부색 특성을 고려하여, 밝기 성분을 제거한 RGB 컬러를 모두 사용하는 H, Cb, Cg의 다채널 피부색 모델을 제시한다. 또한, 색상정보에서 사용하지 않은 밝기 정보는 영상 분할을 통해 사용한다. 제안하는 피부색 모델을 통한 얼굴영역 추출 과정을 보인다.

• Korean Journal of Remote Sensing
• /
• v.38 no.5_1
• /
• pp.511-521
• /
• 2022

Cloud detection and removal from satellite images is an essential process for topographic observation and analysis. Threshold-based cloud detection techniques show stable performance because they detect using the physical characteristics of clouds, but they have the disadvantage of requiring all channels' images and long computational time. Cloud detection techniques using deep learning, which have been studied recently, show short computational time and excellent performance even using only four or less channel (RGB, NIR) images. In this paper, we confirm the performance dependence of the deep learning network according to the heterogeneous learning dataset with different resolutions. The DeepLabV3+ network was improved so that channel features of cloud detection were extracted and learned with two published heterogeneous datasets and mixed data respectively. As a result of the experiment, clouds' Jaccard index was low in a network that learned with different kind of images from test images. However, clouds' Jaccard index was high in a network learned with mixed data that added some of the same kind of test data. Clouds are not structured in a shape, so reflecting channel features in learning is more effective in cloud detection than spatial features. It is necessary to learn channel features of each satellite sensors for cloud detection. Therefore, cloud detection of heterogeneous sensors with different resolutions is very dependent on the learning dataset.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2013.01a
• /
• pp.19-22
• /
• 2013

본 논문은 조명을 제거한 차영상을 이용하여 객체의 움직임을 탐지하는 시스템을 제안한다. 먼저, 입력받은 RGB영상을 Lab영상으로 변환하여 L채널 영상을 분리해낸다. 분리해낸 L채널 영상을 반전시켜 역 조명 영상을 만들어 원 영상과 합성한다. 그 후 만들어진 영상에 모폴로지 기법을 적용하고, 잡음 제거를 위해 크기 필터링을 사용한다. 그리고 배경 영상과 현재 영상의 차영상을 이용하여 객체의 움직임을 탐지한다. 실험 결과 제안된 시스템은 조명이 밝거나 어두워 영상 분석이 힘든 경우, 제대로 분석되지 않은 배경과 전경에 있어서 더욱 효과적으로 작동함을 증명한다.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.6 no.3
• /
• pp.183-188
• /
• 2013

Image watermarking schemes are researched in the field of digital watermarking for multimedia data copyright protection, but color image watermarking scheme is a little bit insufficient. In this paper, we analyzed HSI channel analysis in color models for effective image watermarking. Simulation results are satisfied with invisibility and correlation from the extracted watermark.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.41 no.5
• /
• pp.143-152
• /
• 2004

In this paper, we propose the new algorithms of watermarking that utilize the characteristics of color images for solving the trade-off problem between the image quality and the robustness. Since the human visual characteristics of each RGB channel are different, we can gain more robust watermarking on the condition of the same image degradation.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2018.05a
• /
• pp.169-171
• /
• 2018

정보를 조작하고 은닉하는 기술은 꾸준히 발전하고 있으며 그 가짓수가 매우 다양하다. 이러한 기술들이 성장함에 따라 이에 맞서 조작된 정보를 알아채고 예방 및 방어를 하는 보안 기술들이 함께 진보된다. 본 논문에서는 정보 보안 기술의 발전을 위한 새로운 정보 은닉 기술의 필요성을 근거로 다양한 데이터 표현 방법을 보안 관점에서 이해하고자 한다. 이에 디지털 이미지를 저장하는 데 쓰이는 BMP 파일 포맷 구성이 RGB 3채널임을 이용하여 ASCII 코드값을 채널에 주입해 프로그래밍을 구현하는 기법에 대해 연구하였다. 이 기법은 향후 여러 프로그래밍 언어로 확장됨에 따라 멀티미디어를 활용한 정보보안 분야에서 크게 활용될 것으로 기대하는 바이다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2009.10a
• /
• pp.305-307
• /
• 2009

본 논문에서는 기존의 퍼지 논리를 이용한 필터링 알고리즘의 문제점을 개선하는 동시에 컬러 영상에 적용할 수 있는 퍼지 필터 알고리즘을 제안한다. 제시된 퍼지 필터 알고리즘은 영상의 RGB 컬러 정보를 각각의 R, G, B 채널 영상으로 분리하고, 각 채널 영상에서 마스크가 위치한 기준 픽셀의 잡음 가능성 정도를 퍼지 논리에 적용하여 판단한다. 잡음 정도에 따라서 출력 영상의 화소값을 평균값 또는 중간값으로 결정한다. 제안된 방법을 잡음이 존재하는 칼라 영상에 적용한 결과, 단색 정보를 기준으로 처리하는 기존의 퍼지 필터 방법에 비해서 효과적인 것을 확인하였다.