• Journal of the Korea Computer Graphics Society
• /
• v.14 no.3
• /
• pp.1-9
• /
• 2008

This paper presents a novel optimization-based saliency-preserving method for converting color images to grayscale in a manner consistent with conventional approaches of black-and-white photographers. In black-and-white photography, a colored filter called a contrast filter has been commonly employed on a camera to lighten or darken selected colors. In addition, local exposure controls such as dodging and burning techniques are typically employed in the darkroom process to change the exposure of local areas within the print without affecting the overall exposure. Our method seeks a digital version of a conventional contrast filter to preserve visually-important image features. Furthermore, conventional burning and dodging techniques are addressed, together with image similarity weights, to give edge-aware local exposure control over the image space. Our method can be efficiently optimized on GPU. According to the experiments, CUDA implementation enables 1 megapixel color images to be converted to grayscale at interactive frames rates.

• Journal of KIISE:Computer Systems and Theory
• /
• v.37 no.2
• /
• pp.110-125
• /
• 2010

We present a novel scheme for generating line drawings from 2D images, aiming to facilitate effective visual communication. In contrast to conventional edge detectors, our technique imitates the human line drawing process to generate lines effectively and intuitively. Our technique consists of three parts: line extraction, line rendering, and user guidance. In line extraction, we extract lines by estimating a likelihood function to effectively find the genuine shape boundaries. In line rendering, we consider the feature scale and the blurriness of lines with which the detail and the focus-level of lines are controlled. We also employ stroke textures to provide a variety of illustration styles. User guidance is allowed to modify the shapes and positions of lines interactively, where immediate response is provided by GPU implementation of most line extraction operations. Experimental results demonstrate that our technique generates various kinds of line drawings from 2D images enabled by the control over detail, focus, and style.

• Journal of the Korea Computer Graphics Society
• /
• v.17 no.1
• /
• pp.33-38
• /
• 2011

This paper proposes the method of image cartooning, that makes cartoon-like images of a target, using reference images. We deform a target image using pre-defined reference images. For this deformation, we extract feature points from the target image by Active Appearance Model(AAM) and apply the warping method to the target using feature points of target and feature points of reference image as a basis of warping function. We create simplified cartoon-like images by abstraction of the deformed target image and drawing of edges and quantization of luminance of the abstracted image. Two main concept of cartoon(exaggeration and simplification) is inhered in this method when we use a exaggerated cartoon image as a reference image. It is possible for this method to create various results by control of warping and change of reference image.

• Journal of the Korea Computer Graphics Society
• /
• v.12 no.4
• /
• pp.7-15
• /
• 2006

The ultimate objective of painterly rendering is to express an inputted image as if it is hand drawn. The factors to express this painterly effect are thickness of the brush, direction, texture and the establishment of criteria judging if the produced brush will be drawn on to the canvas. In this paper, the algorithm using density of the edges in determining the criteria whether the brush will be drawn onto the canvas is proposed. Density of edges refers to the quantity of edge in the specific area. And uses the method of finding the location of the brush to be drawn as a unit of dynamic grid as well as expressing consistent directional through direction interpolation. Also, the texture is expressed using various textured brushes. Considering density of edges,We can express detailed area and abstract area. And it result in more human effect of oil painting.

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

• The Journal of the Korea Contents Association
• /
• v.11 no.6
• /
• pp.106-115
• /
• 2011

In this paper, we evaluate the effectiveness of previous shading algorithms in depicting shape of 3d objects. We perform a study in which people are shown an image of one of ten 3D objects shaded with one of eight styles and asked to orient a gauge to coincide with the surface normal at many positions on the object's surface. The normal estimates are compared with each other and with ground truth data provided by a registered 3D surface model to analyze accuracy and precision. Our experiments suggest that people interpret certain shape differently depending on shading of 3d object. This paper offers substantial evidence that current computer graphics shading algorithms can effectively depict shape of 3d objects where the algorithms have the properties of lots of tone steps and uniformly distributed tone steps. This type of analysis can guide the future development of new CG shading algorithms in computer graphics for the purpose of shape perception.

• The Journal of the Korea Contents Association
• /
• v.7 no.9
• /
• pp.26-33
• /
• 2007

NPR is the area of research which does the image creation of the impression where the hazard person who creates made a human intimate image by the hand in objective. NPR in Cartoon-Rendering when the human being recognizes a thing, it is a technique which expresses a thing to use an appearance and the line which are a means of basic and intuitional expression. Also Cartoon the person probably is, the hazard which helps, raises the efficiency of namely meaning delivery and a simplification technique with the means for it uses. Is like this cartoon basic rules where the simplification and omission are life, from modeling, the low of LOD technique which it is using specially actively from game and one pulse communication is having a common point. The research which it sees Cartoon effects of GPU bases which use DirectX Shader programs LOD it leads and it applies the method for about under presenting it expresses Cartoon effects in exterior.

• Journal of KIISE:Computer Systems and Theory
• /
• v.36 no.3
• /
• pp.199-209
• /
• 2009

In this paper, we suggest a stroke level of detail (LOD) based on a saliency density. On painter]y rendering, the stroke LOD has an advantage of making the observer concentrate on the main object and improving accuracy of expression. For the stroke LOD, it is necessary to classify the detailed and abstracted area. We divide the area on the basis of saliency distribution and the level of detailed expression is controlled based on the saliency information. 'We define that the area of which the saliency distribution is high is a major subject that an artist tries to express, it is described in detail. The area of which the saliency distribution is low is abstractly described. Each divided area has the abstraction level. And by adapting the brushes of which sizes are appropriate to each level, it is possible to express the area which needs to be expressed in details from the one which needs to be expressed abstractly.

• Journal of the Korea Computer Graphics Society
• /
• v.15 no.2
• /
• pp.19-34
• /
• 2009

This paper presents an automatic rendering system for 3D meshes which generates images in the style of oriental black ink painting. In this paper, we analyze the characteristics of black ink painting and present some requirements for our black ink rendering system. Then we survey the steps used by artists to create black ink paintings. Based on the analysis of drawing steps, we propose a black ink rendering system which reproduces the key features of black ink painting through three sub-systems: the feature line layer, the interior shading layer, and the media layer. The main contribution of this paper is to introduce new methods which generate realistic and natural results very fast while any simulation methods are not used to satisfy real-time performance. We describe our implementation of each of these, and demonstrate our results in the major three styles of black ink painting: the outline style, the spontaneous style, and the outline-spontaneous style. Our system renders 3D models of moderate complexity at interactive frame rates. As a result, we expect that our system can be directly applied to real-time applications such as computer games and virtual environments.

• Journal of the Korea Computer Graphics Society
• /
• v.14 no.2
• /
• pp.27-33
• /
• 2008

We propose a stylized facial illustration method that expresses important features of a target highly abstractly but effectively from a human facial picture. Our method first detects facial components such as eyes and their associated regions from an input image, and then uses the detected results to render a stylized portrait. Our illustration method mainly consists of two key components and additional components: a tonal illustration component to draw simple tones, a line illustration component to draw a set of lines, and additional illustration components for hair, clothes. etc. The illustration part of the proposed method aims at illustrating features of a target effectively in a highly abstracted way like hand-drawn paintings. In order to achieve this goal, our method adopts an oriental black-ink painting style, which expresses objects effectively with empty spaces and simple expressions such as abstracted lines.