Seung-Taek Ryoo

Directional texture transfer

A texture transfer algorithm modifies the target image replacing the high frequency information with the example source image. Previous texture transfer techniques normally use such factors as color distance and standard deviation for selecting the best texture from the candidate sets. These factors are useful for expressing a texture effect of the example source in the target image, but are less than optimal for considering the object shape of the target image. In this paper, we propose a novel texture transfer algorithm to express the directional effect based on the flow of the target image. For this, we use a directional factor that considers the gradient direction of the target image. We add an additional energy term that respects the image gradient to the previous fast texture transfer algorithm. Additionally, we propose a method for estimating the directional factor weight value from the target image. We have tested our algorithm with various target images. Our algorithm can express a result image with the feature of the example source texture and the flow of the target image.

A study on stackable mosaic generation for mobile devices

With the growing use of mobile devices such as smartphones, tablet PCs, and digital cameras, photography has become an integral part of everyday life. In particular, mobile devices with cameras allow us to easily capture and modify photographs that can be shared via social networks. In this paper, we introduce a mobile device application for converting photographs into photomosaic images. In general, high-quality photomosaics require large databases. However, mobile devices have limited resources; hence it is difficult for such devices to support photomosaics. We propose a method that produces a photomosaic effect using a database that consists of rotatable images. We also propose a solution to the performance issue based on a best match search.

Interactive painterly rendering with artistic error correction

An artist’s painting is affected by factors such as how he observes objects, his skill in using a brush and materials, and the experience that allows him to correctly apply his skills. The process inevitably results in mistakes contrary to the painter’s original intention. This is a distinguishing factor between painting and photography, but this is the essence of the beauty of painting. The inadequacy of a human being to make a painting exactly as he pleases (as a photograph creates a direct representation of itself) is the starting point of creating a creative work. This paper explains the algorithm that reproduces human errors, as well as the stroke data collection method. Although the results of this research are mainly stylized renderings of modern oil paintings, they have unlimited scalability, in that they can play the role to perform a basic framework. These allow the experimentation with many painting styles through the modification of input data and error generation algorithms.

A multi-level depiction method for painterly rendering based on visual perception cue

Increasing the level of detail (LOD) in brushstrokes within areas of interest improved the realism of painterly rendering. Using a modified quad-tree, we segmented an image into areas with similar levels of saliency; each of these segments was then used to control the brush strokes during rendering. We could also simulate real oil painting steps based on saliency information. Our method runs in a reasonable fine and produces results that are visually appealing and competitive with previous techniques.

Artistic image generation for emerging multimedia services by impressionist manner

In this article, we propose the rendering framework for painting-like image generation and general system architecture for mobile device. Especially, we focused on a color division method for generating neo-impressionist images. The French painter, George Seurat, introduced pointillism under the theory that the individual pigments of colors on the canvas are reconstructed on the human retina. Pointillism is a painting technique in which many small brush strokes are combined to form a picture and determines the color of brush strokes based on the optical mixing of juxtaposed colors. In order to express countless separate dots, we form hierarchical points using Wang Tiles contained points. Also palette will be constructed using neo-impressionist colors. Based on this palette, we propose color division algorithm that distributes hierarchical points color to pointillist colors using probability function. Finally, hierarchical points set that applied proposed color division rule is converted into brush strokes that possesses properties such as shape and direction. This rendering algorithm is performed in our proposed system. Our scheme is able to produce a painting with artistic style and be applied to the various platform having the different computing performance and display resolution. This system also can be extended to various imaging devices (IPTV, camera, smart phone, digital photo frame and so on).

A Photomosaic Image Generation on Smartphone

As the usage of mobile device, such as smartphone is becoming common, persons’ interests in user created contents (UCC) are increasing gradually. Especially, the mobile devices combined with camera make that anyone can create UCC easily. In this paper, we introduce the implementation of smartphone application for converting an image which is taken by the phone into a non-photorealistic photomosaic image. Generally, photomosaic requires large database in order to create high quality result. Because the resource of mobile device is restricted, it is hard to store the large database of photomosaic in mobile device. We obtained the effect which increases the database by using the database which consists of rotatable images. We also offer a solution for the performance issue of best match search.

PC Based Drawing Simulation Using Wiimote

The primary controller of Nintendos Wii console is Wii Remote. It has the motion sensor that can recognize users motion as three dimensional coordinate. Also, it can be used as wireless pointing device on personal computer through Bluetooth. In this study, we suggested PC based drawing system using the motion sensor and the IR sensor via Bluetooth communication.

Real-time emotion retrieval scheme in video with image sequence features

In the current Internet environment, a lot of multimedia information is navigated on the on-line computer systems. Among the multimedia information, video sequence has the most valuable and meaningful influence on human emotions. Therefore, one human’s emotions to see and feel the same video can be different from that of others depending on the person’s mental state. In this research, we propose a new real-time emotion retrieval scheme in video with image sequence features. The features of image sequence consist of color information, key frame extraction, video sound, and optical flow. Each video feature is combined with the weight for the emotion retrieval. The experimental results show the new approach of real-time emotion retrieval in video with the better results compared to the previous studies. The proposed scheme will be applied to the many multimedia fields: movie, computer game, video conference, and so on.

Various Artistic Effect Generation From Reference Image

Nowadays smart phone is widely converge and the growth of mobile and small device market is rapidly increasing. And many image based applications are developed for generating contents. In this paper, we propose a system for human-friendly image generation from user chosen reference images. In mobile application research, performance and waiting time is main problems. Because mobile OS is not fast as PC. So we modify previous texture transfer techniques considering waiting time and performance. For this, we modified from scan-line approach to random-access approach. Our proposed system can make various artistic results automatically. From this framework, we develop android operating system based smart phone application. This system can be extended to various imaging devices (IPTV, camera, stylish photo).

Brushstroke Control from Image Saliency

Increasing the level of detail (LOD) in brushstrokes within areas of interest improved the realism of painterly rendering. Using a modified quad-tree, we segmented an image into areas with similar levels of saliency, each of these segments was then used to control the brush strokes during rendering. We could also simulate real oil painting steps based on saliency information. Our method produces results that are visually appealing and good for interactive system.