• Journal of Digital Contents Society
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• v.5 no.3
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• pp.199-204
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• 2004

A problem of many fractal image compression algorithms providing good quality at low bit rate is that the decoding time rests on an iterative procedure whose complexity is imag-dependent. This paper proposes an iterative-free fractal image decoding algorithm to reduce the decoding time. In the proposed method, under the encoder previously with the same codebook image as an initial image to be used at the decoder, the fractal coefficients are obtained through calculating the similarity between the codebook image and an input image to be encoded. As the decoding time could be remarkably reduced. For verifying the validity and universality of proposed method, We evaluated and analyzed the performance of decoding time and image quality for a number of still images and a moving picture with different distributed characteristics.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2001.11b
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• pp.143-146
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• 2001

HDTV(high-definition television)와 개인용 컴퓨터의 발전에 따라 비월주사(interlaced scanning) 방식의 신호와 순차주사(progressive scanning) 방식의 신호 상호간의 변환에 대한 요구가 점점 늘어나고 있다. 이에 따라 비월주사 방식을 순차주사 방식으로 바꾸어주는 순차주사화(deinterlacing)가 활발히 연구되고 있다. 본 논문에서는 부화소(sub-pixel) 단위의 움직임 정보를 고려한 영상재결합 방법을 기반으로 한 순차주사화 알고리즘을 제안한다. 그러나 국부 움직임이 있는 영역에서는 영상재결합이 효과적이지 않으므로 적절한 문턱값을 이용하여 이러한 영역을 결정하고 에지를 이용한 보간 방법으로 순차주사화 한다. 또한 잘못된 움직임 추정으로 야기되는 문제들을 해결하기 위해, 각 영역과 입력 영상에 따라 다른 움직임 에러를 고려해서 정규화 값(regularization parameter)을 결정함으로 움직임 에러를 효율적으로 제거하였다 제안된 방법은 주관적 측면과 객관적인 측면에서 모두 우수한 결과를 실험적으로 보였다.

• Proceedings of the Korean Information Science Society Conference
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• 2007.06b
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• pp.208-213
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• 2007

본 논문에서는 디지털 영상의 해상도를 부화소 기반의 새로운 적응적 선형보간법으로 변경하는 방법을 제안한다. 일반적 선형보간법에서 고정된 위치로 쓰이는 거리계수를 왜곡된 거리 계산에 의한 화소 가중치를 주는 방법으로 개선한다. 이를 계산하기 위하여 최소 평균 자승 에러(minimum mean square error, MMSE)를 이용한다. 원영상과의 차이를 최소화하는 왜곡 거리 계산을 위하여 이웃한 보간 화소와 왜곡거리를 참조하게 된다. 이를 사용하면 복잡도가 높지 않은 효과적인 화소 보간을 할 수 있고 실험 결과 일반적인 보간법과 비교할 때 PSNR(peak signal to noise ratio)과 주관적 화질 면에서 우수함을 알 수 있었다.

• Journal of IKEEE
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• v.19 no.1
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• pp.1-9
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• 2015

This paper proposes the design of sub-pixel interpolation circuit for real-time multi-decoder supporting 4K-UHD video images. The proposed sub-pixel interpolation circuit supports H.264, MPEG-4, VC-1 and new video compression standard HEVC. The common part of the interpolation algorithm used in each video compression standard is shared to reduce the circuit size. An intermediate buffer is effectively used to reduce the circuit size and optimize the performance. The proposed sub-pixel interpolation circuit was synthesised by using 130nm standard cell library. The synthesized gate-level circuit consists of 122,564 gates and processes 35~86 image frames per second for 4K-UHD video at the maximum operation frequency of 200MHz. Therefore, the proposed circuit can process 4K-UHD video in real time.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.531-534
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• 2012

기존의 히스토그램을 이용한 샷 전환 탐지 방법은 연속적인 두 프레임의 전체 또는 대응되는 동일한 크기의 소 영역의 히스토그램을 사용하며, 객체의 이동이나, 프레임의 밝기 변화에 취약한 문제점이 있다. 본 논문에서는 이 문제점들을 해결하기 위하여 연속적인 두 프레임(현재와 참조 프레임)을 소영역으로 분할한 후, 현재 프레임의 소 영역과 두 프레임사이에서 발생할 수 있는 객체의 이동을 고려한 참조 프레임에서의 소 영역의 비교, 그리고 참조 프레임의 소 영역에서 얻은 화소 밝기 히스토그램에 밝기 변화를 보상한 후, 현재 프레임의 소 영역에서 얻은 화소 밝기 히스토그램과 비교하는 방법을 제안한다. 제안한 방법은 영화와 뉴스 같은 비디오 데이터에 좋은 결과를 보였다.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.6
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• pp.779-788
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• 2015

The SONAR waterfall image(SWI) is used typically to target detection in SONAR operation and is managed with additional data linked in the naval combat system. The SWI and additional data are very important to classify a kind of target. Although additional data of the SWI is essential and must be kept together with the SWI, it was stored separately in the current system. In this paper, we propose an improved information management method in the naval combat system, where additional data can be contained in the SWI together by using information hiding techniques. The experimental results show that the effectiveness of information hiding techniques in the naval combat system. It is demonstrated that the information hiding techniques can be applied to the SWI that can make the naval combat system to be robust and secure.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.2
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• pp.372-379
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• 2015

The latest video compression standard (such as H.264/AVC and HEVC) utilizes quarter-pel accuracy motion estimation in order to retain detailed motion information. Many sub-pixel motion estimation algorithms used in the spatial domain usually encounters increment of computational complexity due to embedded interpolation algorithm. In this paper, an approach to measure sub-pixel accuracy motion estimation in frequency domain using shifting matrix is proposed. Complexity can be reduced utilizing shifting matrix algorithm in frequency domain and simulation results demonstrate not only higher PSNR but lower bit rates than spatial domain algorithms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.2
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• pp.164-173
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• 2013

In this paper, we propose multi-frame based super resolution algorithm by using motion vector normalization and edge pattern analysis. Existing algorithms have constraints of sub-pixel motion and global translation between frames. Thus, applying of algorithms is limited. And single-frame based super resolution algorithm by using discrete wavelet transform which robust to these problems is proposed but it has another problem that quantity of information for interpolation is limited. To solve these problems, we propose motion vector normalization and edge pattern analysis for 2*2 block motion estimation. The experimental results show that the proposed algorithm has better performance than other conventional algorithms.

• Ecology and Resilient Infrastructure
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• v.9 no.3
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• pp.154-162
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• 2022

In this study, a technique for estimating water surface velocity fields in the Universal Transverse Mercator coordinate system using the GPS information of a propagating drone but not ground control points is developed. First, we determine the image direction in which the upper side of an image is directed based on the navigation information of the drone. Subsequently, we assign the start and end frames of the video used and determine the analysis range. Using these two frames, we segment the measurement cross-section into a few subsections at regular intervals. At these subsections, we analyze 30 frame images to create spatio-temporal volumes for calculating the velocity fields. The results of the developed method (propagating drone surface image velocimetry) are compared with those of the existing method (hovering drone surface image velocimetry), and relatively good agreement is indicated between both in terms of the velocity fields.

• Journal of Digital Contents Society
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• v.11 no.3
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• pp.393-398
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• 2010

Composite and compact devices equipped with the functionality of digital still image acquisition, such as cellular phones and MP3 players are widely available to common users. In addition, the application of digital still images is becoming common among security and digital recording devices. The amount of still images, that are maintained or shared in personal storage or massive storage provided by various web services, are rapidly increasing. These still images are bound with file names or identifiers that are provided arbitrarily by users or that are generated from device specific naming method. However, those identifiers are vulnerable for unexpected changing or eliminating so that it becomes a problem in still image search or management. In this paper, we propose a method for still image identifier generation that is created from the still image internal information.