• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.282-285
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• 2006

This paper analyzed the characteristics of the Lossy JPEG of the meteorological satellite image, and analyzed the quality of the Lossy JPEG compression, which is proper for the LRIT(Low Rate Information Transmission) to be serviced to the SDUS(Small-scale Data Utilization Station) system of the COMS(Communication, Oceans, Meteorological Satellite). Since COMS is to start running after 2008, we collected the data of the MTSAT-1R(Multi-functional Transport Satellite -1R) for analysis, and after forming the original image to be used to LRIT by each channel and time zone of the satellite image data, we set the different quality with the Lossy JPEG compression, and compressed the original data. For the characteristic analysis of the Lossy JPEG, we measured PSNR(Peak Signal to Noise Rate), compression rate and the time spent in compression following each quality of Lossy JPEG compression. As a result of the analysis of the satellite image data of the MTSAT-1R, the ideal quality of the Lossy JPEG compression was found to be 90% in the VIS Channel, 85% in the IR1 Channel, 80% in the IR2 Channel, 90% in the IR3 Channel and 90% in the IR4 Channel.

• 한국인쇄학회지
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• 제18권2호
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• pp.55-68
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• 2000

Joint photographic experts group (JPEG) is a standard still-image compression technique, established by the international organization for standardization (ISO) and international telecommunication standardization sector (ITUT). The standard is intended to be utilized in the various kinds of color still imaging systems as a standard color image coding format. Because JPEG is a lossy compression, the decompressed image pixel values are not the same as the value before compression. Various distortions of JPEG compression and JPEG recompression has been reported in various papers. The Image compressed by JPEG is often recompressed by same type compression method in JPEG. In general, JPEG is a lossy compression and the quality of compressed image is predicted that is varied in according to recompression Q-factor. In this paper, four difference color samples(photo image, gradient image, gradient image, vector drawing image, text image) were compressed in according to various Q-factor, and then the compressed images were recompressed according to various Q-factor once again. As the result, this paper evaluate the variation of image quality and file size in JPEG recompression and recommed the optimum recompression factor.

• 한국인쇄학회:학술대회논문집
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• 한국인쇄학회 2000년도 춘계 학술발표회 논문집
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• pp.17-24
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• 2000

The Joint Photographic Experts Group (JPEG) is a standara still-image compression technique, established by the International for Standardization (ISO) and International Telecommunication Standardization Sector (ITUT). The standard is intended to be utilized in the various kinds of color still imaging systems as a standard color image coding format. Because JPEG is a lossy compression, the decompressed image pixel values are nto the same as values before compression. Image of JPEG compression is often made to JPEG recompression at saving to apply JPEG compression of color image. In general, JPEG is a lossy compression and compression image is predicted to be varied image quality according to recompressed Q-factor. Various distortions of JPEG compression and JPEG recompression has been reported in previous paper. In this paper, we compress four difference color samples (photo image, gradient image, vector drawing image, text image) according to various Q-factor, and then compressed images are recompressed according to various Q-factor once again. As the results, we inspect variation of quality and file size of recompressed color image, and ensure the optimum recompression factor.

• 대한전자공학회논문지SD
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• 제40권1호
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• pp.45-51
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• 2003

본 논문은 차세대 정지영상 압축 표준으로서 Wavelet 변환과 Bit-plane 단위의 산술부호화(Arithmetic coding)에 기반한 JPEG2000 코덱의 Wavelet 변환과 양자화기의 하드웨어적 구조를 제안하고, 설계하였다. DWT(Discrete Wavelet Transform)는 Lossy coding과 Lossless coding에 각각 적용할 수 있는 Daubechies 9/7 필터와 Daubechies 5/3 필터를 선택 가능하도록 설계하였으며 양자화기는 Scalar Quantization 방식를 사용하였다. 설계된 DWT와 양자화기는 Xilinx FPGA technology를 이용하여 Synopsys에서 합성한 후 동작을 검증하였으며, 설계된 블록을 30㎒로 동작 시켰을 때 640×480 크기의 걸려 이미지의 경우 초당 10프레임의 성능을 보인다.

• 대한디지털의료영상학회논문지
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• 제4권1호
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• pp.166-180
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• 1998

$\cdot$ 영상 압축은 영상의 통계학적 분포, 반복성을 이용하여 빈도가 높은 데이터는 적은 수의 bits를, 빈도가 낮은 데이터에는 보다 많은 수의 bits를 할당하여 전체 영상을 나타내는 bits 수를 줄이는 것임. $\cdot$ 영상 압축은 크게 Lossy Coding, Lossless Coding으로 나뉘며, Lossy coding은 DCT, 양자화기, VLC Codes를 쓰며 압축 율은 높으나 원래의 영상을 정확히 복원하지 못함. $\cdot$ 영상 압축에 대한 국제 규격 협회는 JPEG, MPEG I, MPEG II, MPEG IV, H.261, H.263 등이 있으나 본 seminar에서는 JPEG 규격만 논함. $\cdot$ 의학 영상은 Resolution이 크고 study 단위로 관리되기 때문에 영상 데이터량이 많으나 진단의 목적으로 쓰이기 때문에 주로 lossless 압축을 쓰게 되나 압축율이 낮음.(3:1 이하). 최근에는 Fractal, Wavelet Coding을 통한 압축율을 증가 시키는 Image Compression Algorithms이 활용됨. $\cdot$ MPEG은 동영상의 압축 표준안이며, 동영상은 한frame 당 25개 이상의 정지 화상으로 이루어지기 때문에 JPEG 규격에서 사용되었던 기법이 그대로 활용되며 영상과 영상간, 또는 frame과 frame 간의 여상의 변화, 움직임을 Vector로 coding하는 interframe Coding 기법을 활용하나 설명하기에는 광범위한 topic이므로 본 seminar에서는 생략함.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.286-289
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• 2006

This paper analyzed the JPEG compression performance of MTSAT-1R(Multi-functional Transport Satellite - 1 Replacement), which is offering the LRIT/HRIT(Low Rate Information Transmissio / High Rate Information Transmission) service now, in order to design the system regarding LRIT/HRIT of COMS(Communication, Ocean and Meteorological Satellite). To do so, we analysed Lossy and Lossless JPEG compression performance regarding the MTSAT-1R LRIT/HRIT data for 10 days, and made comparison to the image characteristics, and understood the JPEG compression characteristics regarding JPEG compression of geostationary meteorological satellite. This result of compression performance analysis is expected to be a reference not only to the system design and realization of COMS LRIT/HRIT but also to those who develop other meteorological satellite receiving systems.

• 대한원격탐사학회지
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• 제22권5호
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• pp.463-468
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• 2006

This paper analyzed the JPEG compression performance of MTSAT-lR (Multi-functional Transport Satellite-1 Replacement), which is offering the LRIT/HRIT (Low Rate Information Transmissio/High Rate Information Transmission) service now, in order to design the system regarding LRIT/HRIT of COMS (Communication, Ocean and Meteorological Satellite). To do so, we analysed Lossy and Lossless JPEG compression performance regarding the MTSAT-1R LRIT/HRIT data for 10 days, and made comparison to the image characteristics, and understood the JPEG compression characteristics regarding JPEG compression of geostationary meteorological satellite. This result of compression performance analysis is expected to be a reference not only to the system design and realization of COMS LRIT/HRIT but also to those who develop other meteorological satellite receiving systems.

• 대한의용생체공학회:의공학회지
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• 제15권2호
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• pp.175-182
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• 1994

The international standard for digital compression and coding of continuous-tone still image known as JPEG (Joint Photographic Experts Group) standard is investigated for medical image archiving and communication. The JPEG standard has widely been accepted in the areas of electronic image communication, computer graphics, and multimedia applications, however, due to the lossy character of the JPEG compression its application to the field of medical imaging has been limited. In this paper, the JPEG standard is investigated for medical image compression with a series of head sections of magnetic resonance (MR) images (256 and 4096 graylevels, $256 {\times}256$size). Two types of Huffman codes are employed, i. e., one is optimized to the image statistics to be encoded and the other is a predetermined code, and their coding efficiencies are examined. From experiments, compression ratios of higher than 15 were obtained for the MR images without noticeable distortion. Error signal in the reconstructed images by the JPEG standard appears close to random noise. Compared to existing full-frame bit-allocation technique used for radiological image compression, the JPEG standard achieves higher compression with less Gibb's artifact. Feature of the progressive image build-up of the JPEG progressive coding may be useful in remote diognosis when data is transmitted through slow public communication channel.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1992년도 추계학술대회
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• pp.29-33
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• 1992

We examine the compression performance of two irreversible (lossy) compression techniques, ADCT-VQ (Adaptive Discrete Cosine Trandform - Vector Quantization) and JPEG (Joint Photographic Experts group) which are basis of medical image information systems. Under the same compression ratio, MSE(Mean Square Error) is 0.578 lower in JPEG than in ADCT-VQ while SNR(Signal to Noise Ratio) is 1.236 dB higher in JPEG than in ADCT-VQ.

• 대한전기학회논문지:시스템및제어부문D
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• 제55권3호
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• pp.124-130
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• 2006

A wavelet-based image compression system allowing both lossless and lossy image compression is proposed in this paper. The proposed algorithm consists of the two stages. The first stage uses the wavelet packet transform and the quad-tree coding scheme for the lossy compression. In the second stage, the residue image taken between the original image and the lossy reconstruction image is coded for the lossless image compression by using the integer wavelet transform and the context based predictive technique with feedback error. The proposed wavelet-based algorithm, allowing an optional lossless reconstruction of a given image, transmits progressively image materials and chooses an appropriate wavelet filter in each stage. The lossy compression result of the proposed algorithm improves up to the maximum 1 dB PSNR performance of the high frequency image, compared to that of JPEG-2000 algorithm and that of S+P algorithm. In addition, the lossless compression result of the proposed algorithm improves up to the maximum 0.39 compression rates of the high frequency image, compared to that of the existing algorithm.