• 한국컴퓨터정보학회논문지
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• 제24권2호
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• pp.41-48
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• 2019

Digital image watermarking techniques have been studied in various fields in order to protect the copyright of multimedia contents mostly composed by images. JPEG compression is a representative copyright attack for image watermarking. The CRT-based watermarking methods in DCT domain have been studied, because these are robust for JPEG compression attack. In this paper, we propose a new method with improved performance compared with the existing CRT based methods in DCT domain. The proposed method selects the DCT block according to the denseness at the watermark insertion phase, and iteratively adjust the CRT Conditional coefficients at the watermark extraction. This paper shows that it is more robust for the JPEG compression attacks through experimental results.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2007년도 추계종합학술대회
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• pp.97-100
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• 2007

기존의 JPEG은 낮은 bit-rate에서의 화질열화현상과 고압축에서의 블록화 영상 등의 단점에 의해 새로운 정지영상 압축 방법이 요구되었다. 이에 차세대 정지영상 표준으로 등장한 것이 JPEG2000이다. JPEG2000 표준은 DWT(Discrete Wavelet Transform)과 EBCOT Entropy Encoding 기술을 기반으로 하고 있다. EBCOT(Embedded block coding with optimized truncation)은 JPEG2000 표준에서 실제 압축을 수행하는 가장 중요한 기술 중 하나이다. 하지만 EBCOT는 bit-level 처리를 하기 때문에 대부분의 연산 시간을 차지하고 있다. 이 때문에 EBCOT의 연산속도를 높이기 위한 연구가 많이 이뤄지고 있다. 이에 본 논문은 JPEG2000 표준의 특징을 이용하여 연산 구조를 개선시킨 Context 추출 방법을 제안한다. 제안한 알고리즘은 고해상도 Multi-Component 정지영상의 압축을 위한 JPEF2000 Encoder Hardware에 적용될 것이다.

• 한국산업정보학회논문지
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• 제12권5호
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• pp.14-22
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• 2007

PACS is an integrated communication network system which is consists of image acquisition devices, storage archiving units, display stations, computer processors, and database management systems. In medical industry, they have been introduced the medical equipments through PACS systems based on the DICOM standard. In this paper, we have reviewed the visual quality performance of various JPEG and JPEG2000 compression options for medical images. Through the realized the transmission mode on DICOM standard, the developed DICOM viewer has been shown in medical applications.

• 방송공학회논문지
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• 제13권1호
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• pp.99-108
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• 2008

본 논문에서는 디지털시네마의 효율적인 배급을 위해서 시각적 무손실 압축 개념을 도입하여 정리하고 효과를 분석한다. 최근 디지털시네마 배급은 DCI에서 채택한 JPEG 2000을 영상 압축 표준으로 이루어지고 있다. 따라서 DCI 규격에 정의된 JPEG 2000의 특징을 살펴본 후, 디지털시네마에서 중요한 시각적 무손실 개념을 정리한다. 실험을 통해 DCI 규격에서 규정한 방식으로 JPEG 2000의 압축성능을 시각적 무손실 관점에서 평가했으며, 그 결과 영화 배급에 필요한 품질 기준을 만족하는 것으로 판단된다.

• 치과방사선
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• 제26권2호
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• pp.191-200
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• 1996

This study was performed to determine the adequate resolution and compression method in teleradiology. A digital imaging system using Machintosh IT ci computer, 15' Sony high resolution RGB monitor, Umax Power look flatbed scanner with transparency unit and 12 panoramic radiographs were used. The results were as follows : 1. Relative detectability at the group scanned by 30ddpi, 600dpi and 1200dpi was same as those at the real panoramic radiographs. 2. Perceivable image quality degradation was found at the 25％ of middle quality of JPEG compression. But those were not diagnostically significant. 3. Perceivable image quality degradation was found at the 100％ of low quality of JPEG compression. And 8cases among them were diagnostically significant. On the basis of the above results, it is considered that the adequate resolution in scanning radiographs for teleradiology is 300dpi and compression method is the middle quality of JPEG compression.

• Journal of information and communication convergence engineering
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• 제6권1호
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• pp.29-33
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• 2008

This paper presents the proposal and hardware design of JPEG baseline encoder. The JPEG encoder system consists of line buffer, 2-D DCT, quantization, entropy encoding, and packer. A fully pipelined scheme for JPEG encoder is adopted to speed-up an image compression. The proposed architecture was described in VHDL and synthesized in Xilinx ISE 7.1i and simulated by modelsim 6.1i. The results showed that the performance of the designed JPEG baseline encoder is higher than that demanded by real-time applications for $1024{\times}768$ image size. The designed JPEG encoder IP can be easily integrated into various application systems, such as scanner, PC camera, color FAX, and network camera, etc.

• 한국인쇄학회지
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• 제20권1호
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• pp.146-158
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• 2002

JPEG is good for full color representation but is poor in quality of image because of the small size and the losing compression ways. GIF is a kind of format style made for image - transmission in Compuserve which is a method of PC communication in U. S. A and now is used in world wide web owing to the efficiency of file compression and transmission. But GIF only is used 256 colors, so the images in web has a poorer quality of colors effect to be compared with those of printed catalogues. Also there can be licence problems when the images is used for commercial uses because the possession is Compuserve. The PNG is a way that the total advantages of JPEG and GIF. PNG image file is a more skillful (bitmap display unit), shows a high quality image like TIFF image about, gives superior compression , a 10% to 30% represents full color, 256 color, gray like JPEG. GIF file which uses LZW compression file is a thing which pays licence, In other hands, PNG is free from licence and more skillful image processing method against image error, and it is possible to conserve the color information. Therefore, this treatise is about how various images which are utilized for commercial printings in web, can be made into PNG files about the compression file. And the representation of image by compared the G]U images with JPEG images as well as compression file and the representation of image the superiority of color representation. In addition, 1 check out how much ranges the PNG files are available for electronic publish printing.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권10호
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• pp.5056-5078
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• 2018

In this work we propose a compression technique that makes use of linear and perceptually uniform CIE $La^*b^*$ color space in the JPEG image compression framework to improve its performance at lower bitrates. To generate quantization matrices suitable for the linear and perceptually uniform CIE $La^*b^*$ color space, a novel linear Contrast Sensitivity Function (CSF) is used. The compression performance in terms of Compression Ratio (CR) and Peak Signal to Noise Ratio (PSNR), is further improved by utilizing image dependent, variable and non-uniform image sub-blocks generated using a proposed histogram-based merging technique. Experimental results indicate that the proposed linear CSF based quantization technique yields, on an average, 8% increase in CR for the same reconstructed image quality in terms of PSNR as compared to the conventional YCbCr color space. The proposed scheme also outperforms JPEG in terms of CR by an average of 45.01% for the same reconstructed image quality.

• 대한전자공학회논문지SD
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• 제39권2호
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• pp.7-13
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• 2002

USB 카메라를 이용하여 PC 화상 회의를 할 때 image sensor에서 읽어드린 동화상을 USB를 통해서 PC로 전송하게 되는데 이 때 USB의 전송 속도의 제한 때문에 동화상의 압축이 필요하다. 동화상의 압축을 위해서는 많은 양의 메모리가 필요하므로 외부 메모리를 사용하는 것이 일반적이다. 동화상 압축 알고리즘은 여러 가지가 있지만 JPEG을 사용할 경우 동화상 프레임을 모두 저장할 필요는 없으며, JPEG 압축 엔진으로 일정한 속도로 들어오는 데이터와, JPEG에서 사용되는 데이터의, 순서의 불일치를 해결해주는JPEG 입력 버퍼만이 필요하다. JPEG 입력 버퍼는 읽고 쓰는 순서가 차이가 많이 나므로 double buffering을 사용하는 것이 일반적이지만 이 논문에서는 double buffering을 사용하지 않고 칩 안에 내장 되는데 문제가 없는 적은 메모리 요구량으로 구현하는 방법을 제안한다. 제안된 메모리 아키텍처를 사용하면 별도의 외부 메모리가 필요하지 않으므로 부품 감소에 의한 전체적인 비용 절감이 가능하다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권4호
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• pp.1457-1470
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• 2015

In wireless multimedia sensor networks (WMSN), the latency of transmission is an increasingly problem. With the improvement of resolution, the time cost in image and video compression is more and more, which seriously affects the real-time of WMSN. In JPEG system, the core of the system is DCT, but DCT-JPEG is not the best choice. Block-based DCT transform coding has serious blocking artifacts when the image is highly compressed at low bit rates. APBT is used in this paper to solve that problem, but APBT does not have a fast algorithm. In this paper, we analyze the structure in JPEG and propose a parallel framework to speed up the algorithm of JPEG on GPU. And we use all phase biorthogonal transform (APBT) to replace the discrete cosine transform (DCT) for the better performance of reconstructed image. Therefore, parallel APBT-JPEG is proposed to solve the real-time of WMSN and the blocking artifacts in DCT-JPEG in this paper. We use the CUDA toolkit based on GPU which is released by NVIDIA to design the parallel algorithm of APBT-JPEG. Experimental results show that the maximum speedup ratio of parallel algorithm of APBT-JPEG can reach more than 100 times with a very low version GPU, compared with conventional serial APBT-JPEG. And the reconstructed image using the proposed algorithm has better performance than the DCT-JPEG in terms of objective quality and subjective effect. The proposed parallel algorithm based on GPU of APBT also can be used in image compression, video compression, the edge detection and some other fields of image processing.