• 한국멀티미디어학회논문지
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• 제7권12호
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• pp.1680-1691
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• 2004

One of the representative methods of optical flow is a gradient method which estimates the movement of an object based on the differential of image brightness. However, the method is ineffective for large displacement of the object and many improved methods have been proposed to copy with such limitations. One of these improved techniques is the multigrid processing, which is used in many optical flow algorithms. As an alternative novel technique we have been proposing an orthogonal functional expansion method, where whole displacements are expanded from low frequency terms. This method is expected to be applicable to flow estimation with large displacement and deformation including expansion and contraction, which are difficult to cope with by conventional optical flow methods. In the orthogonal functional expansion method, the apparent displacement field is calculated iteratively by a projection method which utilizes derivatives of the invariant constraint equations of brightness constancy. One feature of this method is that differentiation of the input image is not necessary, thereby reducing sensitivity to noise. In this paper, we apply our method to several real images in which the objects undergo large displacement and/or deformation including expansion. We demonstrate the effectiveness of the orthogonal functional expansion method by comparing with conventional methods including our optimally scaled multigrid optical flow algorithm.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1994년도 FIFTH WESTERN PACIFIC REGIONAL ACOUSTICS CONFERENCE SEOUL KOREA
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• pp.686-691
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• 1994

For evaluating the response fluctuation of the actual environmental acoustic system excited by arbitrary random inputs, it is important to predict a whole probability distribution form closely connected with evaluation indexes Lx, Leq and so on. In this paper, a new type evaluation method is proposed by introducing three functional models matched to the prediction of the response probability distribution from a problem-oriented viewpoint. Because of the positive variable of the sound intensity, the response probability density function can be reasonably expressed theoretically by a statistical Laguerre expansion series form. The relationship between input and output is described by the regression relationship between the distribution parameters(containing expansion coefficients of this expression) and the stochastic input. These regression functions are expressed in terms of the orthogonal series expansion and their parameters are determined based on the least-squares error criterion and the measure of statistical independency.

• 한국멀티미디어학회논문지
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• 제3권4호
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• pp.380-388
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• 2000

변위량을 계산하여 영상 쌍의 대응점을 추출하는 방법중에서 대표적인 Hom & Schunck 수법이 있고, 이는 미분법을 기초하기 때문에 변위가 큰 변위량 추정을 위하여는 적당치 않다. 본 논문에서는 이러한 종래의 수법으로는 계측이 곤란하였던 이동량이 큰 변위의 변위량을 추정할 수 있는 직교 함수 전개법을 제안한다. 종래의 Horn & Schunck 수법에 의한 변위량은 국소적처리를 출발점으로 하는bottom-up수법으로 구하였으나, 직교 함수 전개법에서는 이와는 반대로 영상 전체의 움직임을 직교함수의 저차 모드부터 순차 전개하는 top-down수법을 이용한다. 직교 함수 전개법을 이용하여 변위량을 구하는 방법은 명도의 적분치 불변의 구속 조건에 관한 도함수를 이용하는 투영법에 의한 반복 계산으로 얻어진다. 마지막으로 구하여진 변위량과 제1원영상으로부터 제2의 영상을 합성하고, 합성된 영상과 제2의 원영상과 NRMS오차와 상관값을 비교하여 그 유효성을 보인다.