• Journal of Broadcast Engineering
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• v.11 no.1 s.30
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• pp.54-65
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• 2006

In this paper, we propose a new functionality to Scalable Video Coding (SVC), which is the support of multiple ROIs for heterogeneous display resolution. Scalable video coding is targeted at giving temporal, spatial, and quality scalability for the encoded bit stream. Region of interest (ROI) is an area that is semantically important to a particular user, especially users with heterogeneous display resolutions. The bitstream containing the ROIs could to be extracted without any transcoding operations, which may be one of way to satisfy QoS. To define multiple ROI in SVC, we adapted FMO, a tool defined in H.264, and based on it, we propose a way to encode and decode ROIs. The proposed method is implemented on the JSVM1.0 and the functionality is verified using it.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.3C
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• pp.158-166
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• 2005

Even though post-processing methods based on projections onto convex sets (POCS) have shown good performance for blocking artifact reduction, it is infeasible to implement POCS for real-time practical applications. This paper proposes DCT domain post-processing method based on POCS. The proposed method shows very similar performance compared to the conventional POCS method, while it reduces tremendously the computational complexity. DCT domain POCS performs the lowpass filtering in the DCT domain, and it removes the inverse DCT and forward DCT modules. Through the investigation of lowpass filtering in the iterative POCS method, we define kth order lowpass filtering which is equivalent to the lowpass filtering in the kth iteration, and the corresponding kth order DCT domain POCS. Simulation results show that the kth order DCT domain POCS without iteration gives very similar performance compared to the conventional POCS with k iterations, while it requires much less computations. Hence the proposed DCT domain POCS method can be used efficiently in the practical post-processing applications with real-time constraints.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.4C
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• pp.411-417
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• 2007

The rate control is an essential component in video coding to provide better quality under given coding constraints, such as channel capacity, frame rates, etc. In general, source data cannot be described as a single distribution in a video coding, hence it can cause an exhaustive approximation problem. It drops a coding efficiency under weak channel environments, such as mobile communications. In this paper, we design a new quantization parameter decision model that is based on a rate-distortion function of generalized Gaussian distribution. In order to adaptively express various source data distribution, we decide a shape parameter by observing a ratio of samples, which have a small value. For experiment, the proposed algorithm is implemented into H.264/AVC video codec, and its performance is compared with that of MPEG-2 TM5, H.263 TMN8 rate control algorithm. As shown in simulation results, the proposed algorithm provides an improved quality rather than previous algorithms and generates the number of bits closed to the target bits.

• Journal of Korea Multimedia Society
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• v.15 no.9
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• pp.1086-1092
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• 2012

In this paper, we propose the rate control scheme reducing frame skipping at low bit-rate. As the method considering lossy parts in the compressing process at the existing scheme, the proposed scheme is improved by subtracting the converted bits from the target bit-rate of the current frame. The converted bits are the value resulted from multiplying the ratio of the current frame MAD to the previous frame MAD by the compressed bits changed from the remaining values after compressing the previous frame.

• Archives of design research
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• v.12 no.1
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• pp.51-60
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• 1999

Since the appearance of moving images, the expansion of mass media such as 1V or VCR has made the pace and range of spreading information to people faster and widely popular. Recendy, the development of digital image technique has resulted in solving the problem -great defect- of the display quality of analogue system; special effects by means of computer graphics have risen to a higher quality level; showed the new direction of digital image; and popular wi1h people all c:Ner the world. This paper reestablishes the notion of image up to now, and analyses the technical differences between analogue system and digital system on the basis of the SpecifIC property and skill of digital image editing; it also studies the special effects which can be applied to the image editing software. Moreover, in researdting 1V advertising, the special effects by digital system in use in 1his country today complies with the statistics in their own field. The special effects in 1V advertising is performed at a higher standard by a professional production. Accordingly, with the help of technology of digital moving image, the special effects are expected to continue developing into a level of high quality

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.5
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• pp.35-42
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• 2008

In this paper, we propose a fast coeff_token decoding method based on the re-constructed VLCT. Since the conventional decoding method is still based on large memory accesses, it is not suitable for the multimedia services such as PMP, PMB, DVH-H where fast decoding and low power consumption are required. Based on the analysis for the codeword structure, new structure of the codeword and the corresponding memory architecture are developed in this paper. The simulation results show that the proposed algorithm achieves memory access saving from 10% to 57%, compared to the conventional decoding method. This meant that the issues of tow power consumption and high speed decoding can be resolved without video-quality and coding efficiency degradation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.12
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• pp.1604-1611
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• 2020

Light field image captured by a microlens array-based camera has many limitations in practical use due to its low spatial resolution and angular resolution. High spatial resolution images can be easily acquired with a single image super-resolution technique that has been studied a lot recently. But there is a problem in that high angular resolution images are distorted in the process of using disparity information inherent among images, and thus it is difficult to obtain a high-quality angular resolution image. In this paper, we propose light field angular super-resolution that extracts an initial feature map using an dilated convolutional neural network in order to effectively extract the view difference information inherent among images and generates target image using a residual neural network. The proposed network showed superior performance in PSNR and subjective image quality compared to existing angular super-resolution networks.

• Journal of Broadcast Engineering
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• v.28 no.1
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• pp.3-20
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• 2023

A computer-generated hologram (CGH) is a digitally calculated and recorded hologram in which the amplitude and phase information of an image is transmitted in free space. The CGH is in the form of a complex hologram, but it is converted into a phase-only hologram to display through a phase-only spatial light modulator (SLM). In this paper, in the process of including the amplitude information of an object in the phase information, when a technique that includes subsampling such as DPAC is used, we showed experimentally that the bandwidth of the phase-only hologram increases, and as a result, aliasing that was not present in the complex hologram can occur. In addition, it was experimentally shown that it is possible to generate a high-quality phase-only hologram by restricting the spatial frequency range even at a distance where the numerical reconstruction performance is degraded by aliasing.

• Journal of Korean Society for Geospatial Information Science
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• v.8 no.1 s.15
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• pp.51-63
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• 2000

Dynamic traffic assignment(DTA) has been a topic of substantial research during the past decade. While DTA is gradually maturing, many aspects of DTA still need improvement, especially regarding its formulation and solution algerian Recently, with its promise for In(Intelligent Transportation System) and GIS(Geographic Information System) applications, DTA have received increasing attention. This potential also implies higher requirement for DTA modeling, especially regarding its solution efficiency for real-time implementation. But DTA have many mathematical difficulties in searching process due to the complexity of spatial and temporal variables. Although many solution algorithms have been studied, conventional methods cannot iud the solution in case that objective function or constraints is not convex. In this paper, the genetic algorithm to find the solution of DTA is applied and the Merchant-Nemhauser model is used as DTA model because it has a nonconvex constraint set. To handle the nonconvex constraint set the GENOCOP III system which is a kind of the genetic algorithm is used in this study. Results for the sample network have been compared with the results of conventional method.

• Journal of the Korean Society of Radiology
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• v.12 no.1
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• pp.47-52
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• 2018

Brain perfusion CT scanning is often employed usefully in clinical conditions as it accurately and promptly provides information about the perfusion state of patients having acute ischemic stroke with a lot of time constraints and allows them to receive proper treatment. Despite those strengths of it, it also has a serious weakness that Lens may be exposed to a lot of dose of radiation in it. In this study, as a way to reduce the dose of radiation to Lens in brain perfusion CT scanning, this researcher conducted an experiment with Bismuth shielding and change of patients' position. TLD (TLD-100) was placed on both lens using the phantom (PBU-50), and then, in total 4 positions, parallel to IOML, parallel to IOML (Bismuth shielding), parallel to SOML, and parallel to SOML (Bismuth shielding), brain perfusion scanning was done 5 times for each position, and dose to Lens were measured. Also, to examine how the picture quality changed in different positions, 4 areas of interest were designated in 4 spots, and then, CT number and noise changes were measured and compared. According to the results of conducting one-way ANOVA on the doses measured, as the significance probability was found to be 0.000, so there was difference found in the doses of radiation to crystalline lenses. According to the results of Duncan's post-hoc test, with the scanning of being parallel to IOML as the reference, the reduction of 89.16% and 89.66% was observed in the scanning of being parallel to SOML and that of being parallel to SOML (Bismuth shielding) respectively, so the doses to Lens reduced significantly. Next, in the scanning of being parallel to IOML (Bismuth shielding), the reduction of 37.12% was found. According to the results, reduction in the doses of radiation was found the most significantly both in the scanning of being parallel to SOML and that of being parallel to SOML (Bismuth shielding). With the limit of the equivalent dose to Lens as the reference, this researcher conducted comparison with the dose to occupational exposure and dose to Public exposure in the scanning of being parallel to IOML and found 39.47% and 394.73% respectively; however in the scanning of being parallel to SOML (Bismuth shielding), considerable reduction was found as 4.08% and 40.8% respectively. According to the results of evaluation on picture quality, every image was found to meet the evaluative standards of phantom scanning in terms of the measurement of CT numbers and noise. In conclusion, it would be the most useful way to reduce the dose of radiation to Lens to use shields in brain perfusion CT scanning and adjust patients' position so that their lens will not be in the field of radiation.