Tae Shick Wang

Wavelet based seam carving for content-aware image resizing

In this paper, a novel content-aware image resizing method based on wavelet analysis is proposed. We estimate the local energy map of an image by weighing its multiscale subbands appropriately. Based on the energy map, the image is resized by repeatedly carving out or inserting in a connected path of pixels which is least significant in terms of the energy. Since wavelet analysis is similar to the way the human visual system operates, the obtained energy map reflects human perception with fidelity, and thus, the semantic information in the image can be preserved faithfully in the resizing process. The experimental results show that the proposed method produces higher subjective quality images than scaling and conventional content-aware image resizing techniques.

Improved seam carving using a modified energy function based on wavelet decomposition

In this paper, a novel content-aware image resizing technique, perceptually improved seam carving with modified energy function, is proposed. The conventional seam carving method using a gradient-based energy function may cause distortion of deformed object shape depending on the layout and amount of contents. However, the proposed method preserves content shape with high fidelity by exploiting a wavelet-based energy function which represents image features effectively within the scale-space framework. To prevent excessively distorting the images, a switching scheme between seam carving and resampling is proposed based on the energy distribution. Experimental results show that the proposed method can achieve higher subjective image quality than the existing methods including scaling and conventional seam carving.

Video stabilization based on motion segmentation

This paper presents a new approach for video stabilization based on motion segmentation. The performance of video stabilization depends on the accuracy of the global motion. However, the scenes with large depth variation yield the performance degradation. In the proposed method, the feature points are detected and tracked, and their displacements are examined over the two adjacent frames. Motion segmentation is performed based on the similarity of the feature point displacements. The global motion is finally estimated using the feature points with the dominant motion which are located in similar depth ranges in most cases. Experimental results show that the proposed method provides the superior performance of video stabilization over the conventional method.

An efficient re-coloring method with information preserving for the color-blind

In this paper, a fast re-coloring method with information preserving is proposed for the color-blind (CB) who experiences difficulty to discriminate some color differences. In the proposed algorithm, we utilize a new color transform that can enhance the perceptibility for the CB while maintaining the re-colored image as natural as possible for the normal viewer. In addition, an improved method which effectively detects the CB unperceivable (CBU) colors to be re-colored is introduced. Experimental results show that the proposed method can produce more comprehensible images for CB viewers while preserving the naturalness of the recolored images for standard viewers with reduced complexity.

Enhanced frame rate up-conversion method for UHD video

In this paper, a segment-based motion estimation (ME) method for frame rate up-conversion is proposed that can achieve better visual quality for next generation video formats. The proposed ME method can reduce the computational complexity of the ME drastically by adjusting the search range (SR) for each segment and adopting a new efficient distortion criterion, called the subsampled sum of absolute differences (SSAD). The proposed method does not degrade the motion accuracy by using the temporal consistency of the segment with large size. Experimental results show that the proposed algorithm outperforms conventional methods both objectively and subjectively with the significantly reduced computational complexity.

Improved block truncation coding for color image compression in LCD overdrive

The overdrive techniques have been widely used to reduce motion blur on liquid-crystal displays (LCD). However, these techniques require a large size of the frame buffer to shorten the response time of the liquid crystal. In this paper, we propose an improved block truncation coding (BTC) that can significantly reduce the memory used for the overdrive. Experimental results show that the proposed algorithm improves the compression ratio by a factor of two while maintaining the edge preservation characteristics as compared with the conventional BTC algorithm.

Video transcoding to support playback at a random location for scalable video coding

In many applications including Internet video broadcast and interactive TV, video streams are transmitted over various networks. In order to fulfil the requirement of the users who want to watch a part of the video stream, start playback at a random location, and jump to another location, the service provider has to implement the random access functionality. In addition, when the video stream is transmitted over error-prone networks like wireless LAN, the random access point can be used as a recovery point which enables the user device to refresh the decoding process corrupted by the transmission error. In this paper, we propose a simple transcoding algorithm inserting the random access point in the pre-encoded video stream. The multimedia server adopting the proposed transcoding algorithm can support the error-resilient transmission as well as the playback at random location. Experimental results show that the proposed method can gain significant reduction in the complexity without introducing degradation on visual quality.

Enhanced re-coloring method with an information preserving property for color-blind person

Various image re-coloring methods have been developed to enhance the perceptibility of the image for the color-blind. Recently, some methods have been proposed to produce the re-colored images that are not only visually perceptible for color deficient viewers but also look natural for normal observer. However, the methods are impractical to apply to the consumer devices due to its high complexity. Therefore, in this paper, an efficient re-coloring method that utilizes color clustering is proposed. The proposed method detects visually important region to further enhance perceptibility of re-colored images. Experimental results show that the proposed method can provide more comprehensible images for the color-blind person while maintaining the original color information.

Real-time video re-coloring algorithm considering the temporal color consistency for the color-blind

In this paper, a fast color modification method is proposed for the color-blind (CB) who experiences difficulty in discriminating some color differences. The proposed algorithm uses a new perceptual illusion based color transform technique that can enhance the color contrast for the CB while preventing significant change of the original image. In addition, a fast temporal color adjustment technique is introduced for the real-time video playback. Experimental results show that the proposed method can produce more comprehensible video sequences for the CB with reduced computational complexity.

Fast frame rate up-conversion using motion vector verification for LCD devices

In this paper, we propose a fast frame rate up-conversion (FRUC) for reducing the motion-blur in liquid-crystal display (LCD) devices. Prior to the re-estimation of the motion vector (MV), required by the conventional method, we exploit a verification process to check whether the received MV is reliable or not. Then, the MV re-estimation is selectively performed for the unreliable MV to obtain the accurate MV. Therefore, the proposed method generates the interpolated frames with low computational complexity. Experimental results show that the proposed algorithm outperforms the conventional methods in both PSNR and visual performance.