• Journal of Internet Computing and Services
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• v.8 no.3
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• pp.33-43
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• 2007

In this proper, we proposes a robust watermarking against the lossy compression in the Hadamard domain. The Hadamard matrix consists of only 1 or -1 and can be computed veru fast. The Hadamrd transform has the inverse transform therefore it is able to be applied into the watermarking technology. In embedding process, we select 10 coefficients from intermediate frequency domain and create two watermark patterns. In extraction process, we use the watermark patterns and compare them to detect the watermark information. When we use the standard image ($512{\times}512$) and binary watermark image ($64{\times}64$), the results of these examines are PSNR for $38{\sim}42dB$ and BER for $3.9{\sim}12.5%$. The JPEG QF between 30 and100, naked human eyes can detect to watermark image easily. The experimental results show that performance of Hadamard domain is better than those of DCT, FFT, and DWT.

• Journal of IKEEE
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• v.22 no.3
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• pp.774-779
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• 2018

This paper presents fragile watermark system using quantization and DC coefficients. It is a way to prevent the watermark fro, being detected if the original has been modified in any way. In other words, the detection of a watermark ca be said to be originality after the watermark is inserted, without any damage. Since lossy compression such as JPEG is often allowed or required in practical applications, authentication methods, authentication methods should be distinguished from malicious modifications such as image shifting, cropping, filtering, and replacement. The proposed algorithm implements a fragile watermarking algorithm that shows image authentication with JPEC compression and the watermark easily breaks other malicious variants.

• Journal of The Korean Association of Information Education
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• v.8 no.1
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• pp.113-125
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• 2004

A new on-line essay test system that write the articles to manuscript paper which has two hundred squares for characters, look over and correct the manuscript paper in environment of on-line network like the real essay test is designed and implemented in this thesis. Using this system, a participant can write the articles to manuscript paper, a scorer look over and can correct the articles on manuscript paper directly. When looking over and correcting manuscript paper in this system, scorer can use a pen-mouse and a tablet. To reduce the network traffic, bitmap format of the manuscript paper is compressed to JPEG format before it is transmitted to server. The system is cost-effective and has lots of advantages in efficiency and usability. Furthermore, it is expected that the developed system can be used to improve the field of on-line subjective examinations as a counterproposal.

• Journal of The Korean Association of Information Education
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• v.8 no.1
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• pp.1-13
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• 2004

A new on-line essay test system that write the articles to manuscript paper which has two hundred squares for characters, look over and correct the manuscript paper in environment of on-line network like the real essay test is designed and implemented in this thesis. Using this system, a participant can write the articles to manuscript paper, a scorer look over and can correct the articles on manuscript paper directly. When looking over and correcting manuscript paper in this system, scorer can use a pen-mouse and a tablet. To reduce the network traffic, bitmap format of the manuscript paper is compressed to JPEG format before it is transmitted to server. The system is cost-effective and has lots of advantages in efficiency and usability. Furthermore, it is expected that the developed system can be used to improve the field of on-line subjective examinations as a counterproposal.

• Journal of Korea Multimedia Society
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• v.9 no.11
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• pp.1445-1454
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• 2006

To compress a specific part of an image with high quality or to transfer it, JPEG2000 standard offers an ROI(Region-of-Interest) image coding method. What is important in ROI coding is to process relative importance between ROI and background and to process ROI mask. We propose an adaptive ROI coding method supplemented the existing Implicit ROI coding and Modified implicit ROI coding to improve image quality and reduce ROI mask information. The proposed method is an EBCOT-based ROI coding that extracts ROI from the compressed bitstream, and gets the ROI mask information by classifying the codeblocks into 6 patterns. The information includes the pattern type(3bit) and the width(5bit) expressing the boundary between two regions for each codeblock. As a result, the method shows an excellent compression performance in ROI region as well as in the whole region of an image.

• Journal of Digital Contents Society
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• v.12 no.1
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• pp.1-9
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• 2011

JPEG2000 offers the technique which compresses the interested regions with higher quality than the background. It is called by an ROI(Region-of-Interest) coding method. In this paper, we use images including the human faces, which are processed uppermost and compressed with high quality. The proposed method consists of 2 steps. The first step extracts some faces and the second one is ROI coding. To extract the faces, the method cuts or scale-downs some regions with $20{\times}20$ window pixels for all the pixels of the image, and after preprocessing, recognizes the faces using neural networks. Each extracted region is identified by ROI mask and then ROI-coded using Maxshift method. After then, the image is compressed and saved using EBCOT. The existing methods searched the ROI by edge distributions. On the contrary, the proposed method uses human intellect. And the experiment shows that the method is sufficiently useful with images having several human faces.

• The Transactions of the Korea Information Processing Society
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• v.7 no.1
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• pp.296-305
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• 2000

In this paper, we propose the method of embedding the encrypted digital watermark in quantization coefficient when we encode the image data in the process of JPEC. The proposed method is as following. After a DCT coefficient of each block is quantized, we arrange the quantization coefficient as on dimension with a zigzag scan and replace each block. By applying even-odd feature of frequency of the encrypted watermark to a quantization coefficient of some fixed domain of replaced each block and embedding it, we obtain the compressed image data by encoding after placing it in the order prior to replacement. The advantages of the proposed method here are as follows: We can embed many information keeping a secret as much as possible by using the algorithm of block replacement. We can control the amount of embedding of each use, as we embed the encrypted information by selecting some fixed domain of a quantization coefficient, we can fix the embedding data regardless of the image and the value of quantization. We verified the results by experiments and analyzed the efficiency of them in comparison with the former study.

• Journal of the Korea Society of Computer and Information
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• v.12 no.5
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• pp.39-47
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• 2007

In this thesis, a method of generating an adaptable Region-Of-Interest(ROI) Mask for the Region-Of-Interest coding is suggested. In the method, an ROI Mask is generated using the information of the ROI designated by a user. In the existed method of ROI coding, after scanning all the pixels in order and discriminating an ROI, an ROI Mask is generated. But, in our method, after scanning a part of pixels based on the shape pattern of an ROI and discriminating a ROI by one code block unit, an ROI Mask is generated. Moreover, from the method, a pattern number, threshold of a ROI and background threshold parameter are provided. According to the result of its comparing test with the existed methods to show the usability, it is proved that our method is superior in speed to the existed ones.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.3
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• pp.679-686
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• 2014

Recently, users can get countless images and videos by network. So, the compression technology of image and video is researched more and more. However, the situation which is the interested range of the image is occurred. For instance, since the region of face is more important than background, the image compression technology bases on the region of interest (ROI) is necessary, in the ATM environment. In this research, given the human visual system, which are not sensitive to illumination variations at very dark and light regions of image, we calculate the standard deviation of block and use this value to define the ROI. In encoding process, the relatively high quality can be obtained at the ROI and the relatively low quality can be obtained at the non ROI. In proposed scheme, the feature which is the encoding process according to subjectively image quality can be demonstrated. Finally, this proposed scheme is applied to JPEG standard. The experimental results demonstrate that proposed scheme can achieve better image quality at the high compression ratio.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2003.11a
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• pp.61-64
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• 2003

무손실 이미지 압축은 (Lossless Image Compression)은 손실이미지 압축(Lossy Image Compression)에 비해, 압축률(compression ratio)은 떨어지지만, 반면 원이미지와 복원이미지가 완전히 일치하므로, 원인이미지의 품질을 그대로 유지학 수 있다. 따라서, 이미지의 품질(Quality)과 압축효율(compression ratio)은 서로 상반된 관계에 있으며, 지금도 좀 더 놀은 압축효과를 얻으려는 여러 무손실 압축 방법이 발표되고 있다. 무손실 이미지 압축은 이미지의 정확성과 정밀성이 요구되는, 의료영양분야에서 가장 널리 쓰이고 있으며, 그밖에, 원본이미지를 기본으로 다른 이미지프로세싱이 필요한 경우, 압축 복원을 반복적으로 수행할 필요가 있을 때, 기타 사진 예술분야, 원격 영상 등 정밀성이 요구되는 분양에서 쓰이고 있다. [7]. 무손실 이미지 압축의 가장 대표적인 CALIC[3]과 JPEG_LS[2]를 들 수 있다. CALIC은 비교적 높은 압축률을 나타내지만, 3-PASS의 과정을 거치는 복잡도가 지적되고 있다. 반면 JPEG-LS는 압축률은 CALIC에 미치지 못하지만 빠른 코딩/디코딩 속도를 보인다. 본 논문에서는 여거 가지의 예측 모드를 두어, 블록단위별로 주변 CONTEXT에 따라, 최상의 예측 모드를 판단하여, 이를 적용, 픽셀의 여러 값을 최소화하였다. 그 후 적응산술 부호기(Adaptive arithmetc coder)를 이용하여, 인코딩을 하였다. 이때 최대 에러값은 64를 넘지 않게 했으며, 또한 8*8블록별로 에러의 최대값을 측정하여 그 값을 $0\~7$까지의 8개의 대표값으로 양자화하는 방법을 통하여 그에 따라 8개의 보호화 심볼 모델중 알맞은 모델에 적용하였다. 이를 통해, 그 소화값의 확률 구간을 대폭 넓힘으로써, 에러 이미지가 가지고 있는 엔트로피에 좀 근접하게 코딩을 할 수 있게 되었다. 이 방법은 실제로 Arithmetic Coder를 이용하는 다른 압축 방법에 그리고 적용할 수 있다. 실험 결과 압축효율은 JPEG-LS보다 약 $5\%$의 압축 성능 개선이 있었으며, CALIC과는 대등한 압축률을 보이며, 부호화/복호화 속도는 CALIC보다 우수한 것으로 나타났다.