• Proceedings of the Korean Information Science Society Conference
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• 2004.10a
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• pp.382-384
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• 2004

최근 가파른 증가세를 보이며 그 기법 또한 다양해지고 있는 공격에 대한 사후처리와 동일 침입 방지를 위해, 네트워크 포렌직에 대한 관심이 커지고 있다. 포렌직을 위해서는 정보의 손실 없는 네트워크 트래픽을 수집하여 보존하는 것이 필요하지만, 그 양이 막대하며, 이는 더 큰 용량의 디스크를 필요로 한다. 이를 해결하기 위해서는 압축을 수행하는 것이 필요하며, 또한 IP와 같이 필요로 하는 몇몇 정보를 압축해제 없이 접근할 수 있게 한다면, 간단한 작업을 위해서도 압축을 풀기 위해 컴퓨팅 파워와 시간을 줄일 수 있을 것이다. 따라서, 이 논문에서는 수집한 패킷마다 압축을 수행할 부분과 수행하지 않을 부분으로 나누고, 압축을 수행한 뒤, 해당 정보를 4바이트의 헤더로 만들어 덧붙임으로써, 기존 트래픽을 압축함과 동시에 패킷들에 대한 간단한 정보들을 압축해제 없이 접근할 수 있는 모델을 제안하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2022.06a
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• pp.74-77
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• 2022

본 논문에서는 계층적 픽셀 예측과 컨텍스트 적응적 산술 부호화를 이용한 이미지 적응 무손실 압축 알고리즘을 제안한다. 입력 RGB 이미지는 먼저 가역적 색상 변환이 적용된다. Y 채널 이미지는 기존의 무손실 압축 인코더로 압축되고, U와 V채널 이미지는 Y 채널 이미지를 기반으로 예측된다. 원본과의 차이는 컨텍스트 적응적 산술 부호화를 통해 압축된다. 본 논문에서 제안된 알고리즘에서는 입력 이미지의 성질에 따라 산술 부호화에 사용되는 인코더의 개수를 적응적으로 변화시킨다. 또한 저주파 성분에 상대적으로 많은 자원을 집중시킴으로써 압축 성능을 향상시켰다. 제안된 방법은 기존에 사용되던 압축 방식들과 비교했을 때에도 의미 있는 성능을 보였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2021.11a
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• pp.966-968
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• 2021

본 논문에서는 효과적인 고해상도 비디오 데이터의 처리를 위하여 부호화기 내에서 참조 영상을 저장하는 프레임 메모리를 압축하는 방법을 제안한다. 프레임 메모리는 응용분야의 특성상 무손실 압축 및 저 복잡도를 갖는 방법이 요구되는데, 블록 단위의 PCT 를 이용하여 픽셀 사이의 상관도를 제거하고, 적응적 GR 부호기를 이용하여 최종 비트열을 구성하여 압축하는 방법을 제안한다. 다양한 테스트 영상을 대상으로 실험한 결과 제안하는 방법이 기존의 압축 방법에 비해 압축 성능이 우수하면서 실행 시간으로 측정한 복잡도 측면에서 유사한 성능을 나타냄을 확인하였다. 압축 성능과 복잡도의 두가지 측면을 종합적으로 판단한 결과 제안하는 방법이 기존의 방법에 비해 충분히 경쟁력이 있음을 알 수 있다.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.3
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• pp.36-41
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• 2002

Generally, cartoon images are simple and involve a small number of colors and often include large homogeneous regions with same color or gradient. In this paper, effective compression method for complementary quadtree was suggested for cartoon images, by using those properties. And with progressive transmission, this method involves a progressive increase in the image resolution at the receiver from a lower to a higher resolution during the transmission of data. This is an effective way of using a limited transmission channel, because, after estimating the value of the data in the early transmission period, a decision can be made whether or not to proceed with the transmission of the remaining part. Since the proposed method is lossless and involves progressive transmission, it was compared with progressive PNG and progressive GIF, which had same functions.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.9
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• pp.92-103
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• 2012

In this paper, we discuss and propose a new algorithm of coding technique for scalably servicing holographic video in various decoding environment. The proposed algorithm consists of the hologram-based resolution scalable coding (HRS) and the light source-based SNR scalable coding (LSS). They are classified by the method generating and capturing hologram. HRS is a scalable coding technique for the optically captured hologram and LSS is one for the light source before generating hologram. HRS can provide the scalable service of 8 steps with the compression ratio from 1:1 to 100:1 for a $1,024{\times}1,024$ hologram. LSS can also provide the various service depending on the number of the light source division using lossless compression. The proposed techniques showed the scalable holographic video service according to the display with the various resolutions, computational power of the receiving equipment, and the network bandwidth.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.11
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• pp.1356-1363
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• 2016

In this paper, we propose a novel error detection algorithm for LZ78-compressed data. The conventional error detection method adds a certain number of parity bits in transmission, and the receiver checks the number of bits representing '1' to detect the errors. These conventional methods use additional bits resulting in increased redundancy in the compressed data which results in reduced effectiveness of the final compressed data. In this paper, we propose error detection algorithm using the structural properties of LZ78 compression without using additional bits in the compressed data. The simulation results show that the error detection ratio of the proposed algorithm is about 1.3 times better for error detection than conventional algorithms.

• Convergence Security Journal
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• v.9 no.2
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• pp.79-84
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• 2009

Recently, Move Picture Files have the same file format and a compression technique as Window Media Video form. but Moving Pictures using file format and a compression technique have question about Motion blur and compressibility. In this paper, we design and Implement for new Move Picture Solution EZ-MOV using FLV different from developed FLV(Flash Video) in the Macromedia company. EZ-MOV have advantages as follow. first, FLV player is able to compact disk access time and DRM (Digital Rights Management) with a built-in self and unable to an illegal video recording, second, whenever WMV formal file encoded FLV are able to lossless compression to fifty percent, third, FLV is able to Moving Picture streaming no buffering. fourth, FLV file is able streaming service no streaming server. fifth, FLV file is able to streaming service keep pace with download and streaming. sixth, FLV file is able to full duplex service.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5C
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• pp.371-381
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• 2005

In this paper, we propose an advanced hardware architecture for the CAVLC entropy encoder/decoder engine for real time video compression. The CAVLC (Context-based Adaptive Variable Length Coding) is a lossless compression method in H.264/AVC and it has high compression efficiency but has computational complexity. The reference memory size is optimized using partitioned storing method and memory reuse method which are based on partiality of memory referencing. We choose the hardware architecture which has the most suitable one in several encoder/decoder architectures for the mobile devices and improve its performance using parallel processing. The proposed architecture has been verified by ARM-interfaced emulation board using Altera Excalibur and also synthesized on Samsung 0.18 um CMOS technology. The synthesis result shows that the encoder can process about 300 CIF frames/s at 150MHz and the decoder can process about 250 CIF frames/s at 140Mhz. The hardware architectures are being used as core modules when implementing a complete H.264/AVC video encoder/decoder chip for real-time multimedia application.

• The Transactions of the Korea Information Processing Society
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• v.3 no.6
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• pp.1624-1635
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• 1996

Palletized color images are the dominant type of the image used on Internet and World-Wide Web. In spite of this, most image compression and progressive transmission algorithm have been designed for continuous-tone images. Pallettize images. Palletized images differ from continuous-tone images in such a aspect that values are lookup table indices a new pyramid structure for compression and progressive transmission of a palletized image. In the proposed pyramid structure, the color of a node at higher level is the one that occupies the most part in 4 sons and each node is represented by a type code and several color codes. Since the proposed method do not exploit spatial correlation in an image, it is ideally applied to lossless compression and progressive transmission of palletized images. We have confirmed this through the experimental results.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.504-506
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• 1993

The Joint Photographic Experts Group (JPEG) standard was proposed by the International Standardization Organization (ISO/SC 29/WG 10) and the CCITT SG VIII as an international standard for digital continuous-tone still image compression. The JPEG standard has been widely accepted in electronic imaging, computer graphics, and multi-media applications, however, due to the lossy character of the JPEG compression its application in the field of medical imaging has been limited. In this paper, the JPEG standard was applied to a series of head sections of magnetic resonance (MR) images (256 gray levels, $256{\times}256$ size) and its performance was investigated. For this purpose, DCT-based sequential mode of the JPEG standard was implemented using the CL550 compression chip and progressive and lossless coding was implemented by software without additional hardware. From the experiment, it appears that the compression ratio of about 10 to 20 was obtained for the MR images without noticeable distortion. It is also noted that the error signal between the reconstructed image by the JPEG and the original image was nearly random noise without causing any special-pattern-related artifact. Although the coding efficiency of the progressive and hierarchical coding is identical to that of the sequential coding in compression ratio and SNR, it has useful features In fast search of patient Image from huge image data base and in remote diagnosis through slow public communication channel.