• Journal of Broadcast Engineering
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• v.8 no.1
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• pp.30-36
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• 2003

According to an evolution of image and video compression technologies, most digital images are in the compressed form. Resizing of these compressed images have various applications such as transmission of resized image according to varying bandwidth, content adaptation for display purpose and etc. Discrete Cosine Transform (DCT) is the most popular transformation for image compression. Recently, several researches have been performed to obtain the reconstructed image of original size in the DCT domain after downsampling and upsampling in the DCT domain. Main focus of these researches is to improve quality of the reconstructed image after downsampling and upsampling in the DCT domain In this paper, we present an modified IDCT method to downsize DCT-encoded image. Furthermore, we propose an efficient scheme for image downsampling and upsampling in the DCT domain With these modified IDCT method. The proposed scheme Provides higher PSNR values than the existing schemes In terms of the reconstructed image after halving and doubling in the DCT domain.

• Journal of Broadcast Engineering
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• v.10 no.3
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• pp.286-296
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• 2005

This paper presents a stereo-based image compression and transmission system for 3D realistic television. In the proposed system, a disparity map is extracted from an input stereo image pair and the extracted disparity map and one of two input images are transmitted or stored at a local or remote site. However, correspondences can not be determined in occlusion areas. Thus, it is not easy to recover 3D information in such regions. In this paper, a reconstruction image compensation algorithm based on error block concealment and in-loop filtering is proposed to minimize the reconstruction error in generating stereo image pair. The effectiveness of the proposed algorithm is shown in term of objective accuracy of reconstruction image with several real stereo image pairs.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.12
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• pp.2146-2152
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• 2008

In In this paper, we proposed a new JPEG2000 codec using multiresolution-based rendering (MRBR) technique for video compression of 3-dimensional digital cinema. We introduced discrete wavelet transform (DWT) for stereoscopic image and stereo matching technique in the wavelet domain. The disparity was extracted using stereo matching and transmitted with the reference (left) image. Since the generated right image was degraded by the occlusion lesion, the residual image which is generated from difference between the original right image and the generated one was transmitted at the same tine. The disparity data was extracted using the dynamic programming method in the disparity domain. There is high correlation between the higher and lower subbands. Therefore we decreased the calculation amount and enhanced accuracy by restricting the search window and applying the disparity information generated from higher subband.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.20-25
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• 2019

Most multimedia signals contain image data, so the problem of efficient processing and transmitting the image data is an important task of the information society. This paper proposes a compression algorithm that reduces the color bits according to importance using YUV color space among the various methods of compressing image data. 4: 2: 2 subsampling is the standard in the field of video. Using the color information and the characteristics of the human retina, YUV color data was reduced by 4: 2: 2 subsampling. The YUV images and RGB images can be interconverted using the transformation matrix. The image data was converted into color space by YUV, and the relatively low U and V bits were subjected to a downscaling operation. The data was then compressed through 4: 2: 2 subsampling. The performance of the proposed algorithm was compared and analyzed by a comparison with existing methods. As a result of the analysis, it was possible to compress the image without reducing the information of the low importance color element and without significant deterioration in the quality compared to the original.

• Journal of Korea Multimedia Society
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• v.12 no.7
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• pp.922-928
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• 2009

In H.264 as the newest video standard, 9 modes are used in order to predict the signal values of a block composed with several pixels by intra prediction. From these process, H.264 can bring high compression ratio in the encoded signal but the use of total 9 modes can give the inefficiency of the increase of the complexity induced by the amount of operation processing or the number of searching which is applied to compare adjacent pixels. This paper proposes a simplification method of prediction mode for the intra-picture coding by considering subjective interest region. There are certain region being interested within a picture of the video sequence. This region requires better subjective picture quality than the other regions. The proposed method increases the simplification of prediction mode by providing just essential modes of total 9 modes for less interest regions compared with the interest region. It is possible to get the additional 11%$\sim$15% simplification of the prediction mode by the proposed method, compared with the conventional method which simplifies the prediction mode for all of the picture by using the prediction characteristics only.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.43 no.2 s.308
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• pp.57-64
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• 2006

Tn this paper, We propose a user friendly object-based multimedia retrieval system using the HCNN(HippoCampus Neural Network. Most existing approaches to content-based retrieval rely on query by example or user based low-level features such as color, shape, texture. In this paper we perform a scene change detection and key frame extraction for the compressed video stream that is video compression standard such as MPEG. We propose a method for automatic color object extraction and ACE(Adaptive Circular filter and Edge) of content-based multimedia retrieval system. And we compose multimedia retrieval system after learned by the HCNN such extracted features. Proposed HCNN makes an adaptive real-time content-based multimedia retrieval system using excitatory teaming method that forwards important features to long-term memories and inhibitory learning method that forwards unimportant features to short-term memories controlled by impression.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.9
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• pp.1009-1018
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• 2015

In video coding, the first frame of a GOP is encoded in intra mode which generates a larger number of bits. In addition, the first frame is used for the inter mode encoding of the following frames. Thus the intial QP for the first frame encoding affects the first frame as well as the following frames. To determine the initial QP that maximizes the PSNR of a GOP, several algorithms which uses the ratio of the PSNR of the I frame and the PSNR of P frames of a GOP have been proposed. In this paper, we propose a new traffic model that can be used to determine the optimal initial QP simply and exactly in algorithms that use the PSNR ratio. We first analyze the characteristics of the PSNR ratio of I and P frames and the PSNR of a GOP, and then propose a new traffic model which can represent the characteristics and determine the optimal intial QP. It is shown by experimental results that the initial QP determination method with the proposed model can predict an optimal initial QP whose difference from the optimal value is less than 2. The proposed scheme can also generate the PSNR performance better than that of the existing JVT algorithm.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.10
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• pp.1207-1214
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• 2014

The first frame of a GOP is encoded in intra mode which generates a larger number of bits. In addition, the first frame is used for the inter mode encoding of the following frames. Thus the encoding results of the intra frame affects the first frame as well as the following frames. Traditionally, the quantization parameter for an intra frame is determined only depending on the bpp not considering the characteristics of the intra frame. For accurate intra frame encoding, we should consider not only bpp but also the complexity of the video sequence and the output bandwidth. In this paper, we propose a real-time quantization model which is used to calculate the quantization parameter for an intra frame encoding based on the investigation on the characteristics of a GOP. It is shown by experimental results that the proposed quantization model captures the characteristics of an intra frame effectively and the proposed method for model parameters accurately estimates the real values.

• Journal of Korea Multimedia Society
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• v.13 no.4
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• pp.575-581
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• 2010

With widespread use of the Internet and improvements in streaming media and compression technology, digital music, video, and image can be distributed instantaneously across the Internet to end-users. However, most conventional Digital Right Management are often not secure and not fast enough to process the vast amount of data generated by the multimedia applications to meet the real-time constraints. The SVC offers temporal, spatial, and SNR scalability to varying network bandwidth and different application needs. Meanwhile, for many multimedia services, security is an important component to restrict unauthorized content access and distribution. This suggests the need for new cryptography system implementations that can operate at SVC. In this paper, we propose a new scrambling encryption for reserving the characteristic of scalability in MPEG4-SVC. In the base layer, the proposed algorithm is applied and performed the selective scambling. And it encrypts various MVS and intra-mode scrambling in the enhancement layer. In the decryption, it decrypts each encrypted layers by using another encrypted keys. Throughout the experimental results, the proposed algorithms have low complexity in encryption and the robustness of communication errors.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7B
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• pp.1384-1392
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• 1999

A high compression rate is required to transmit video sequences over low bit rate networks such as low bit rate communication channels. When highly compressed videos are transmitted over mobile channels of high error rate, bitstreams corrupted by channel errors are not only difficult to be decoded, but also have fatal effects on the other parts of the bitstreams. In this Paper, we propose an error concealment algorithm for recovering the blocks which can not be decoded due to damaged bitstreams. The proposed error concealment algorithm recovers the damaged blocks using the information of adjacent blocks which are correctly decoded. In the proposed algorithm, the motion vector of the damaged block is estimated using the overlapped block motion compensation(OBMC) and block boundary matching(BBM) techniques. Experiment results show that the proposed algorithm exhibits better performance in PSNR than existing error concealment methods.