• ETRI Journal
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• v.46 no.3
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• pp.538-549
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• 2024

A conventional codec aims to increase the compression efficiency for transmission and storage while maintaining video quality. However, as the number of platforms using machine vision rapidly increases, a codec that increases the compression efficiency and maintains the accuracy of machine vision tasks must be devised. Hence, the Moving Picture Experts Group created a standardization process for video coding for machines (VCM) to reduce bitrates while maintaining the accuracy of machine vision tasks. In particular, in-loop filters have been developed for improving the subjective quality and machine vision task accuracy. However, the high computational complexity of in-loop filters limits the development of a high-performance VCM architecture. We analyze the effect of an in-loop filter on the VCM performance and propose a suboptimal VCM method based on the selective activation of in-loop filters. The proposed method reduces the computation time for video coding by approximately 5% when using the enhanced compression model and 2% when employing a Versatile Video Coding test model while maintaining the machine vision accuracy and compression efficiency of the VCM architecture.

• Journal of Korea Multimedia Society
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• v.13 no.8
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• pp.1154-1162
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• 2010

Because it is easy to implement the scalar quantizer, it is used in various video coding systems. Although the scalar quantizer with a large quantization stepsize can reduce the amount of data, it has disadvantage that the reconstructed picture quality is poor. In this paper, we propose an efficient method which improves the coding performance by maintaining original quantization stepsize and increasing the number of quantization reconstruction levels. Simultaneously, for the purpose of solving the problem of transmitting the added symbol informations which is used to indicate the region of quantizer reconstruction level as the number of quantizer reconstruction level is increased, we also suggest the method to reduce the added informations. Therefore, for the intra-coded picture of H.264 video coding system, we generate the huffman codes for the symbol informations of quantization reconstruction regions by 4${\times}$4(horizontal 4 pixels, vertical pixels) block unit. Furthermore, for the inter-coded picture, we also generate the huffman codes for the symbol informations of quantization reconstruction regions by 8${\times}$8 blocks and 4${\times}$4 blocks within a macroblock. Adopting this method of reducing the added information by increasing the number of quantization reconstruction region, It is shown that the coding performance can be improved at the same bitrate.

• Korean Journal of Digital Imaging in Medicine
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• v.5 no.1
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• pp.32-44
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• 2002

The role of radiology department has been greatly increased in the past few years as the technology in the medical imaging devices improved and the introduction of PACS (Picture Archiving and Communications System) to the conventional film-based diagnostic structure is a truly remarkable factor to the medical history. In addition, the value of using digital information in medical imaging is highly expected to grow as the technology over the computer and the network improves. However, the current medical practice, using PACS is somewhat limited compared to the film-based conventional one due to a poor image quality. The image quality is the most important and inevitable factor in the PACS environment and it is one of the most necessary steps to more wide practice of digital imaging. The existing image quality control tools are limited in controlling images produced from the medical modalities, because they cannot display the real image changing status. Thus, the image quality is distorted and the ability to diagnosis becomes hindered compared to the one of the film-based practice. In addition, the workflow of the radiologist greatly increases; as every doctor has to perform his or her own image quality control every time they view images produced from the medical modalities. To resolve these kinds of problems and enhance current medical practice under the PACS environment, we have developed a program to display a better image quality by using the ROI optical density of the existing gray level values. When the LUT is used properly, small detailed regions, which cannot be seen by using the existing image quality controls are easily displayed and thus, greatly improves digital medical practice. The purpose of this study is to provide an easier medical practice to physicians, by applying the technology of converting the H-D curves of the analog film screen to the digital imaging technology and to preset image quality control values to each exposed body part, modality and group of physicians for a better and easier medical practice. We have asked to 5 well known professional physicians to compare image quality of the same set of exam by using the two different methods: existing image quality control and the LUT technology. As the result, the LUT technology was enormously favored over the existing image quality control method. All the physicians have pointed out the far more superiority of the LUT over the existing image quality control method and highly praised its ability to display small detailed regions, which cannot be displayed by existing image quality control tools. Two physicians expressed the necessity of presetting the LUT values for each exposed body part. Overall, the LUT technology yielded a great interest among the physicians and highly praised for its ability to overcome currently embedded problems of PACS. We strongly believe that the LUT technology can enhance the current medical practice and open a new beginning in the future medical imaging.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.10a
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• pp.66-72
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• 2000

We have scanned the several seismic traces of earthquakes and blasts observed from the digital new type seismograph instruments of KMA from Jan. 2000 to Aug. 2000. From these data, good quality data which have high signal/noise ratio were selected and they were transformed into ascii data from binary data(mini-seed format). The hypo71 program and P-S was applied in order to determine the location of epicenter, origin time and the magnitude. From these data, the 18 earthquakes and 3 blasts, 207 seismic records consist of 359 directional components were calculated. Using theses ground acceleration data, acceleration, velocity, and displacement response spectrums of the structures were calculated and they could be represented in a picture by the form of tripartite response spectrum. In the result, response spectrums of the 359 directional components of the above seismic data records were obtained respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.1
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• pp.47-58
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• 1996

An object color can be seen differently under the various outer illuminants. However, human visual system has color constnacy that the object color can be seen constantly under the different outer illuminants. When the viewer watches TV under specific that the object color can be seen constantly under the different outer illuminants. When the viewer bathes TV under specific outer illuminants, he perceives distortes color due to the emitting specturm of outer illuminants as well as the radiation of CPT itself. Namely, when the outer illuminants such as fluorescent and incandescent lamps incident on CPT, brightness, saturation, hue, itself. Namely, when the outer iluminants such as fluorescent and incandescent lamps incident on CPT, brightness, saturation, hue, and contrast on color pictures are changend, he perceives distortedcolr fromthe original color. In this paper color enhancement algorithm based on light intensity and outer light decision funtion using RGB sensor was proposed. The implemented TV of proposed algorithm has higher visual quality at the view point of human visual system and more vivid than that ofcoventional color TV.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.1
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• pp.241-250
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• 1996

In this work, an improved architecture of two-dimensional digital filter(2D DF) is suggested, and then the filter is simulated by C, VHDL language and related layouts are designed by Berkeley CAD tools. The 2D DF consists of one-dimensional digital filters and delay lines. For one-dimensional digital filter(1D DF) case, once filter coefficients are represented by canonical signed digit formats, multiplications are exected by hardwired-shifting methods. The related bit numbers are handled to prevent picture quality degradation and pipelined adder architectures are adopted in each tap and output stage to speed up the filter. For delay line case, line-sharing DRAM is adopted to improve power dissipation and speed. The filter layout is designed by semi/full custom methods considering regularity and speed improvement, and normal operation is confirmed by simulation.

• Journal of Advanced Navigation Technology
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• v.11 no.3
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• pp.319-328
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• 2007

In this paper we implemented the Real Time Contrast Enhancer for image quality enhancement of moving picture. Also we proposed adaptive contrast control method that use mean and variance of input video signal. The Designed the contrast Enhancer is measured in comparison with conventional pictures and interfaced to 30inch TFT LCD TV.

• Proceedings of the Korean Society of Computer Information Conference
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• 2013.01a
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• pp.271-272
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• 2013

The music with the times, evolved from analogous tape music to digital music. New authoring tools, interfaces, and applications make us to produce high quality music using cheap equipments. Inspired by this concept, we design an classical chinese style-instrument with the audio-visual interactive function. It enables a user to compose music and to see a vivid picture at the same time.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.152-155
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• 2002

In this paper, a new approach is proposed for the error detection dedicated to MPEG-4 video coding by using the digital watermarking. In the process of encoding, the proposed scheme abstracts the macroblock features of headers, motion vectors, and Discrete Cosine Transform (DCT) coefficients, which are embedded in the quantized DCT coefficients as the digital watermarks. The decoder performs the accurate error detection through the watermark extraction. Simulation results demonstrate that the error detection ability of the proposed approach can be significantly enhanced, and that digital watermark embedding incurs little degradation to the picture quality.

• Proceedings of the IEEK Conference
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• 2000.11d
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• pp.101-104
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• 2000

An efficient bit rate distribution technique that distributes available bits for multiple objects based on motion vector magnitude, size of object shape, and coding distortion is presented. This coding concept using the three parameters was exploited in MPEG-4 multiple object coding. But the scheme is likely to produce poor results such as allocating more bits to less important objects and degrading picture quality, due to the lack of analysis and research in view of human visual aspect. In this paper importance of each object is represented by the three parameters and visually analyzed. Target bits are distributed according to coding distortion using the pre-assigned shape and motion information.