• The KIPS Transactions:PartA
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• v.15A no.2
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• pp.75-86
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• 2008

Black/white comic rendering is one of the researches in the field of non-photorealistic rendering(NPR). Black/white comics have been produced manually as yet. But these previous systems require lots of time and manual work. So we propose the COmics Rendering system on VIdeo Stream (CORVIS) which transforms video streams into black/white comic cuts. Stylized font, one of comic representations, can be used to express onomatopoeic words and mimetic dialogue exaggeratively. But current comic generation systems do not provide enough effects of stylized font. This paper proposes a model for stylized fonts to express various effects. Effects of stylized fonts we proposed include geometric deformations. Thus we could represent stylized fonts on the still cut of movies and the background texture on a cuts of plain black/white comics. The final quality of our system produced is good enough to compare with manual black/white comics.

• Journal of Korea Multimedia Society
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• v.12 no.11
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• pp.1640-1651
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• 2009

In this paper we introduce a new approach to stroke based rendering using brush stroke profile. Our proposed method, based on image retrieval method, is a simple but flexible and scalable method to create various painting styles, for which scalable database constructed with the collection of real stroke data is used. Input image is reproduced with combinations of brush stoke in the database, when a search process to determinate appropriate brush stroke and a judgment process to decide whether to draw the retrieved brush stroke on the canvas or not are presented. In addition, this paper suggests a new brush stroke model and a depiction technique in order to utilize effective height information which allows natural texture depiction, or good visual effect, without carrying out physical simulation. Our method is able to create diverse variations of painting by controling various user parameters. It also provides scalable framework that can produce various painting styles with different artistic media by changing the stroke combinations of stroke database.

• Journal of Korea Multimedia Society
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• v.8 no.4
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• pp.554-568
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• 2005

We suggest the dynamic stroke generation algorithm that provides frame-to-frame coherence in 3D non-photorealistic animations. We use 3D particle system to eliminate the visual popping effect in the animated scene. Since we have located particles on the 3D object's surface, the coherence is maintained when the object or the camera is moving in the scene. Also, this algorithm maintains the coherence when camera is zooming in/out. However, the brush strokes on the surface also zoom in/out. This result(too large or too small brush strokes) can not represent hand-crafted brush strokes. To remove this problem, we suggest stroke generation algorithm that dynamically maintains the number of brush stroke and its size during camera zoom in/out.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.529-534
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• 2009

This paper reports a non-photorealistic rendering method for creating stream pattern from an input image. Our method extracts potential stream pattern in the given image. The proposed approach uses a shock filter based on a partial difference equation(PDE) which is implemented by applying a selective dilation and erosion processes. However, unlike the traditional first order solution to the PDE, we employ a second order scheme and compensate for the undesired diffusive effects caused by a viscosity form. The selection of dilation or erosion for a pixel is based on an edge detector computed from a structure tensor. By adding noises on to the input image, our method also can generate stream pattern even if there is less texture in some area. The experimental results show that the stream pattern is extracted very well.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.12
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• pp.3296-3314
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• 2012

We present a novel approach for the simulation of color pencil effects using line integral convolution (LIC) to produce pencil drawings from images. Our key idea is to use a bilateral convolution filter to simulate the various effects of pencil strokes. Our filter resolves the drawbacks of the existing convolution-based schemes, and presents an intuitive control to mimic the properties of pencil strokes. We also present a scheme that determines stroke directions from the shapes to be drawn. Smooth tangent flows are used for the pixels close to feature lines, and partially parallel flows inside regions. The background is rendered using a flow of fixed direction. Using different styles of stroke directions increases the realism of the resulting images. This approach produces convincing pencil drawing effects from photographs.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.3
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• pp.575-591
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• 2011

We present a novel active contour-based two-pass approach to extract smooth feature regions from a triangular mesh. In the first pass, an active contour formulated in level-set surfaces is devised to extract feature regions with rough boundaries. In the second pass, the rough boundary curve is smoothed by minimizing internal energy, which is derived from its curvature. The separation of the extraction and smoothing process enables us to extract feature regions with smooth boundaries from a triangular mesh without user's initial model. Furthermore, smooth feature curves can also be obtained by skeletonizing the smooth feature regions. We tested our algorithm on facial models and proved its excellence.

• Journal of the Korea Computer Graphics Society
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• v.14 no.1
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• pp.17-25
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• 2008

We proposed the method for photomosaic generation using a programmable GPU. We design vertices to generate a photomosaic through a graphics pipeline and suggest a texture representation of an image database whice is used for tile. Both the source image and the tiles are stored to texture, which are matched by a vertex shader and drawn by a fragment shader. This is much faster than several techniques which achieve the best match for each tile.

• Journal of Korea Multimedia Society
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• v.11 no.6
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• pp.755-763
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• 2008

Silhouette is useful in computer graphics for a number of techniques such as non-photorealistic rendering, silhouette clipping, and blueprint generating. Methods for generating silhouette are classified into three categories: image-based, object-based, and hybrid-based. Hybrid-based method is effective in terms of time complexity but spatial coherence problem still remains. In this paper, we proposed a new hybrid-based method which produces 3D data for silhouette and also guarantees no spatial coherence problem. To verify the efficiency of the proposed algorithm, several experiments are conducted for various 3D models from simple to quite complex. Results show that our algorithm generates no gap between any two consecutive silhouette lines when the silhouette model is magnified significantly.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.712-714
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• 2002

애니메이션에서 가장 중요하게 고려해야 할 문제는 프레임간 유사성을 어떻게 유지하느냐 이다. 각 프레임간 영상의 유사성이 없으면 프레임이 바뀔 때 좋지 못한 영상을 보여주기 때문이다. 또한 3차원 애니메이션을 위한 비사실적 렌더링에서는 프레임간 유사성뿐 아니라 렌더링을 수행하는 방법도 중요하다. 본 논문에서는 프레임간 유사성을 유지하기 위하여 파티클 시스템을 사용한다. 파티클을 물체의 실제 크기에 따라 분포시킴으로써 적절한 파티클의 수를 유지한다. 이때, 물체가 확대, 축소될 경우에는 화면상에서의 물체의 크기에 따라 동적으로 파티클의 수를 조정하게된다. 그리고 비사실적 렌더링을 위하여 붓의 터치를 표현할 스트로크를 사용하는데 스트로크의 방향, 색, 크기 등을 결정하기 위하여 참조 영상을 사용하는 렌더링 방법을 소개한다. 이렇게 결정된 스트로크들의 속성들은 붓 모양의 텍스쳐를 이용하여 렌더링 된다.

• Journal of the Korea Computer Graphics Society
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• v.12 no.2
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• pp.35-38
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• 2006

우리는 3차원 개체로 표현된 옷의 주름을 라플라시안 맵과 옷 주름 맵을 사용하여 실시간에 비사실적으로 표현하는 방법을 제안한다. 옷의 주름을 표현하기 위해, 옷의 주름을 디자이너가 직접 그린 옷 주름 맵과 옷이 변형된 상태에 대한 정보가 계산된 라플라시안 맵을 사용하여, 단순한 GPU연산을 통해 최종적으로 옷의 주름을 표현한다. 실험 결과 우리가 제안한 방법은 옷의 주름을 실시간에 비사실적으로 표현할 수 있으며, 디자이너의 의도한 바대로 주름을 그릴 수 있다는 장점이 있음을 알 수 있었다.