• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2005년도 춘계학술발표대회
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• pp.805-808
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• 2005

엔트로피부호화(entropy coding)는 텍스트와 같은 일반적인 데이터들을 효율적으로 압축하는 반면에, 이미지 데이터들에 대해서는 그 성능이 다소 저하된다. 본 논문에서는 이러한 단점을 개선시키기 위한 효율적인 전처리기법(preprocessing technique)을 소개한다. 제안한 전처리기법은 입력된 명암도 등급 이미지를 무손실 압축하기 이전에, 이미지 내에서 인접한 명암도 값들의 발생빈도(occurrence frequency)를 조사한다. 다음으로 각 픽셀 쌍들의 명암도 값들을 발생빈도에 기반한 순서화된 값(ordered number)들로 대체시킨 후, 최종적으로 엔트로피부호화에 의한 압축을 수행한다. 이와 같은 단계들을 거치면서 이미지 데이터의 통계적인 특성(statistical feature)이 보다 강화되기 때문에, 엔트로피부호화에서의 무손실 압축 성능을 효율적으로 개선시킬 수 있다. 실험을 통하여 256 명암도 등급 이미지들을 산술부호화와 허프만부호화를 사용하여 압축한 결과, 제안한 전처리기법이 압축 후 비트율(bit rate)을 최대 37.49%까지 감소시켰음을 확인하였다.

• 인지과학
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• 제10권3호
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• pp.77-83
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• 1999

1990년대 OCR에 대한 관심이 고조되면서, 다양한 필기 데이터베이스가 전 세계적으로 구축되었다. 그러나, 현재 연구분야에서 직면한 문제는 필기 품질을 포함하여 각기 다양한 방법으로 구축된 데이터베이스 내에서 필기 문자의 품질을 평가하는 것이다. 본 논문은 다양한 필기 데이터베이스를 비교하고, 문자 인식기의 성능을 객관적으로 평가하는데 사용할 수 있는 필기 품질을 측정하는 방법을 제안한다. 여기서 사용된 핵심 아이디어는 각각의 문자 샘플을 필기 품질에 따라 여러 개의 그룹으로 나누는 것이다. 제안된 방법의 성능을 평가하기 위하여, 대용량 필기 한글 데이터베이스인 KU-1 데이터베이스에 대한 실험을 수행한 결과, 제안된 방법이 필기 데이터베이스를 비교하고, 인식기의 성능을 객관적으로 평가하는데 유용하게 사용할 수 있는 가능성을 확인하였다.

• Agricultural and Biosystems Engineering
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• 제6권1호
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• pp.1-7
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• 2005

Assessing health condition of crop in the field is one of core operation in precision fanning. A sensing system was proposed to remotely detect the crop health condition in terms of SP AD readings directly related to chlorophyll contents of crop using a multispectral camera equipped on ground-based platform. Since the image taken by a camera was sensitive to changes in ambient light intensity, it was needed to convert gray scale image data into reflectance, an index to indicate the reflection characteristics of target crop. A reference reflectance panel consisting of four pieces of sub-panels with different reflectance was developed for a dynamic calibration, by which a calibration equation was updated for every crop image captured by the camera. The system performance was evaluated in a field by investigating the relationship between com canopy reflectance and SP AD values. The validation tests revealed that the com canopy reflectance induced from Green band in the multispectral camera had the most significant correlation with SPAD values $(r^2=0.75)$ and NIR band could be used to filter out unwanted non-crop features such as soil background and empty space in a crop canopy. This research confirmed that it was technically feasible to develop a ground-based remote sensing system for assessing crop health condition.

• Journal of Biosystems Engineering
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• 제17권4호
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• pp.354-362
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• 1992

This study was intended to examine feasibility of sizing and color grading of Fuji apple with black/white image processing system, to develop a device with which the whole surface of an apple could be captured by one camera, and to develop an algorithm for a high speed sorting. The results are summarized as follows : 1. The black/white image processing system used in this study showed a maximum error of 1.3% in area measurement with a reference figure while the focusing point of camera and location of the reference figure were changed within a certain range. 2. As the result of evaluating four automatic image segmentation algorithms with apple images, Histogram Clustering Method was the best in terms of computation time and accuracy. 3. The fast algorithm for analyzing size and coloration of apple was developed. 4. The whole surface of an apple could be captured in an image frame with two mirrors installed on the both sides of the sample. The total area of the image representing the whole surface showed a correlation of 0.995 with the weight of apple. 5. The gray level when a particular band pass filter was mounted on the camera showed high correlation with 'L' and 'a' values of Hunt color scale and could represent the coloration of apple.

• 한국항공우주학회지
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• 제44권5호
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• pp.407-415
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• 2016

본 논문에서는 최적의 항공 영상 융합을 위하여 적응 가이디드 필터 기반 알고리즘을 제안하였다. 제안한 적응 가이디드 필터는 가이디드 필터 설계 요소 중에서 정규화 파라미터 값을 입력된 영상 특성에 따라서 조절하고 PSNR (peak signal to noise ratio)을 미리 정해둔 값으로 유지한다. 제안한 방법은 입력 영상의 특성에 관계없이 미리 정한 PSNR을 유지하는 범위 내에서 잡음을 제거하므로 최적의 영상 융합 성능의 결과를 가져올 수 있다. 필터 성능은 시뮬레이션을 통해 검증하였고, 기존에 많이 사용되고 있는 영상융합 품질 파라미터를 이용하여 분석하였다.

• 한국가금학회지
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• 제22권4호
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• pp.233-238
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• 1995

A computer vision system was built to generate images of a single, stationary egg. This system includes a CGD camera, a frame grabber, and incandescent back lighting system. Image processing algorithms were developed to inspect egg shell and to sort eggs. Those values of both gray level and area of dark spots in the egg image were used as criteria to detect holes in egg and those values of both area and roundness of dark spots in the egg image were used to detect cracks in egg. For a sample of 300 eggs, this system was able to correctly analyze an egg for the presence of a defect 97.5% of the time. The weights of eggs were found to be linear to both the projected area and the perimeter of eggs viewed from above. Those two values were used as criteria to sort eggs. The coefficients of determination(r$^2$) for the regression equations between weights and those two values were 0.967 and 0.972 in the two sets of experiment. Accuracies in grading were found to be 95.6% and 96.7% as compared with results from sizing by electronic weight scale.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권1호
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• pp.570-595
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• 2017

Robust and perceptually-adaptive image watermarking algorithms have mainly targeted gray-scale images either at the modeling or embedding levels despite the widespread availability of color images. Only few of the existing algorithms are specifically designed for color images where color correlation and perception are constructively exploited. In this paper, a new perceptual and high-capacity color image watermarking solution is proposed based on the extension of Tsui et al. algorithm. The $CIEL^*a^*b^*$ space and the spatio-chromatic Fourier transform (SCFT) are combined along with a perceptual model to hide watermarks in color images where the embedding process reconciles between the conflicting requirements of digital watermarking. The perceptual model, based on an emerging color image model, exploits the non-uniform just-noticeable color difference (NUJNCD) thresholds of the $CIEL^*a^*b^*$ space. Also, spread-spectrum techniques and semi-random low-density parity check codes (SR-LDPC) are used to boost the watermark robustness and capacity. Unlike, existing color-based models, the data hiding capacity of our scheme relies on a game-theoretic model where upper bounds for watermark embedding are derived. Finally, the proposed watermarking solution outperforms existing color-based watermarking schemes in terms of robustness to standard image/color attacks, hiding capacity and imperceptibility.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권7호
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• pp.3286-3300
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• 2016

High Efficiency Video Coding (HEVC) Standard, as the latest coding standard, introduces satisfying compression structures with respect to its predecessor Advanced Video Coding (H.264/AVC). The new coding standard can offer improved encoding performance compared with H.264/AVC. However, it also leads to enormous computational complexity that makes it considerably difficult to be implemented in real time application. In this paper, based on machine learning, a fast partitioning method is proposed, which can search for the best splitting structures for Intra-Prediction. In view of the video texture characteristics, we choose the entropy of Gray-Scale Difference Statistics (GDS) and the minimum of Sum of Absolute Transformed Difference (SATD) as two important features, which can make a balance between the computation complexity and classification performance. According to the selected features, adaptive decision trees can be built for the Coding Units (CU) with different size by offline training. Furthermore, by this way, the partition of CUs can be resolved as a binary classification problem. Experimental results have shown that the proposed algorithm can save over 34% encoding time on average, with a negligible Bjontegaard Delta (BD)-rate increase.

• 센서학회지
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• 제10권5호
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• pp.286-291
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• 2001

논문에서는 임의의 시각계에서 인간과 유사한 시각 응시점을 선택하기 위한 Saliency map 모델을 제안한다. 제안하는 모델은 영상의 에지 정보를 시각 응시점 결정을 위한 특징 기저로 이용한다. 자연 정지 흑백 영상에서 상호 독립적인 에지 성분들을 찾는데 가장 좋은 방법이라고 알려진 독립성분해석 방법을 이용한다. 인간 시각계에서 시각 수용체의 비균일 분포를 고려하기 위해 카메라와 같은 시각 센서로 받은 영상을 직접 이용하는 대신에 입력 영상으로 다중 해상도를 갖는 계층 영상을 이용한다. 컴퓨터를 이용한 시뮬레이션으로부터 제안한 Saliency map을 이용하여 주어진 임의의 이미지에 대한 시각 응시점을 구한다.

• 한국염색가공학회지
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• 제18권2호
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• pp.15-23
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• 2006

A new fastness formula based on CIEDE2000 color-difference formula is developed by B. Rigg and his coworkers. It is very simple to calculate fastness grade for color change than ISO 105-A05 fastness formula based on CIELAB color-difference formula. Sample pair sets which cover a wide range color space were accumulated from NCS(Natural Color System) color book. For those sample pair sets, visual measurement experiment and instrument measurement experiment of fastness grade were carried out and each performance of ISO 105-A02 fastness formula and newly developed fastness formula was compared through degree of agreement for visual measurement result. Newly developed fastness formula indicated improved performance for measuring fastness grade but current ISO fastness formula for assessing change in color, ISO 105-A05, was confirmed that it's performance is inadequate to measure fastness grade. Then fastness formulae were examined more closely according to particular color spaces and the correlation of hue, lightness and chrom for measuring fastness grade was also considered in this study.