Sung Jea Ko

Motion-Compensated Frame Interpolation Using Bilateral Motion Estimation and Adaptive Overlapped Block Motion Compensation

In this work, we develop a new motion-compe (MC) interpolation algorithm to enhance the temporal resolution of video sequences. First, we propose the bilateral motion estimation scheme to obtain the motion field of an interpolated frame without yielding the hole and overlapping problems. Then, we partition a frame into several object regions by clustering motion vectors. We apply the variable-size block MC (VS-BMC) algorithm to object boundaries in order to reconstruct edge information with a higher quality. Finally, we use the adaptive overlapped block MC (OBMC), which adjusts the coefficients of overlapped windows based on the reliabilities of neighboring motion vectors. The adaptive OBMC (AOBMC) can overcome the limitations of the conventional OBMC, such as over-smoothing and poor de-blocking. Experimental results show that the proposed algorithm provides a better image quality than conventional methods both objectively and subjectively

Fast digital image stabilizer based on Gray-coded bit-plane matching

A fast digital image stabilizer based on the Gray-coded bit-plane matching is proposed which is robust to irregular conditions such as moving objects and intentional panning. The proposed digital image stabilization (DIS) system performs motion estimation using the Gray-coded bit-plane of video sequences, greatly reducing the computational load. This motion estimation method can be realized using only binary Boolean functions which have significantly reduced computational complexity, while the accuracy of motion estimation is maintained. In order to further improve the computational efficiency, the Gray-coded bit-plane matching with the three-step search (3SS) is proposed. Experimental results indicate that the proposed digital image stabilizer is a computationally efficient alternative to existing DIS systems.

New frame rate up-conversion using bi-directional motion estimation

We propose a new frame rate up-conversion algorithm for high quality video. In the proposed scheme, bi-directional motion estimation (ME) is performed to construct the motion vector (MV) field for the frame to be interpolated. Unlike conventional motion-compensated interpolation (MCI) algorithms, the proposed technique does not produce any overlapped pixel and hole region in the interpolated frame, and thus can utilize the overlapped block motion compensation technique to reduce the blocking artifacts. The proposed algorithm is very simple to implement on consumer products when compared to conventional MCI methods. Computer simulation shows a high visual performance of the proposed frame rate up-conversion algorithm.

Digital Image Stabilizing Algorithms Based On Bit-plane Matching

In this paper, we present a new digital image stabilization (DIS) scheme based on bit-plane matching (BPM). The proposed DIS system performs motion estimation using 1-bit planes which are extracted from a video sequence. This motion estimation technique can be realized using only Boolean functions which have significantly reduced computational complexity, while the accuracy of motion estimation is maintained. In the second part of this paper, a median-based motion correction scheme is proposed which is robust to various irregular conditions such as moving objects and intentional panning. Simulation results show that the proposed DIS algorithm exhibits better performance compared with existing other algorithms when applied to real video signals.

A New Histogram Modification Based Reversible Data Hiding Algorithm Considering the Human Visual System

In this letter, we propose an improved histogram modification based reversible data hiding technique. In the proposed algorithm, unlike the conventional reversible techniques, a data embedding level is adaptively adjusted for each pixel with a consideration of the human visual system (HVS) characteristics. To this end, an edge and the just noticeable difference (JND) values are estimated for every pixel, and the estimated values are used to determine the embedding level. This pixel level adjustment can effectively reduce the distortion caused by data embedding. The experimental results and performance comparison with other reversible data hiding algorithms are presented to demonstrate the validity of the proposed algorithm.

An advanced video camera system with robust AF, AE, and AWB control

This paper presents an advanced video camera system which has robust automatic focus (AF), automatic exposure (AE), and automatic white-balance (AWB) control. The proposed AF algorithm decides the correct moving direction of the lens and detects the accurate in-focus state even though the scene is interfered with by the high light intensity. Experimental results demonstrate that the proposed system can be an effective alternative to conventional systems using the hill-climbing method.

Robust digital image stabilization using the Kalman filter

In this paper, we present a new digital image stabilization (DIS) algorithm based on feature point tracking. Feature points well tracked by the Kanade-Lucas-Tomasi (KLT) tracker are used to estimate the global motion between two consecutive image frames. The motion prediction with the Kalman filter (KF) is incorporated into the KLT tracker to further speed up the tracking process. Moreover, we develop an adaptive KF to better handle the intentional motion of the camera. In addition, a new scheme is also proposed to detect the scene change and automatically change the reference frame. Experimental simulation shows that the proposed DIS algorithm has the characteristics of high accuracy, good robustness to different irregular conditions.

An effective de-interlacing technique using motion compensated interpolation

We propose a new de-interlacing algorithm using motion compensated interpolation. In the proposed scheme, motion estimation is first performed between the same parity fields, i.e., the previous and the next field, and then the motion vector is refined in the interpolated field. In conventional motion compensated schemes, a pre-filter such as line averaging is applied to interpolate missing lines before the motion estimation between the opposite parity fields. The proposed scheme does not require the pre-filter because block matching is performed between the same parity fields. For further improvement, a five-point median filter with temporal emphasis is used to reduce the interpolation error caused by incorrect motion. Computer simulation results indicate that the proposed scheme provides a better visual performance than conventional de-interlacing algorithms.

A novel image interpolation method using the bilateral filter

In general, since the noise deteriorates the interpolation performance in digital images, it is effective to employ denoising prior to the interpolation. In this paper, we propose a novel interpolation framework in which denoising and image sharpening methods are embedded. In the proposed framework, the image is first decomposed using the bilateral filter into the detail and base layers which represent the small and large scale features, respectively. The detail layer is adaptively smoothed to suppress the noise before interpolation and an edge-preserving interpolation method is applied to both layers. Finally, the high resolution image is obtained by combining the base and detail layers. Experimental results show that the proposed algorithm outperforms the conventional methods while suppressing blurring and jagging.

Vector quantizer based block truncation coding for color image compression in LCD overdrive

The overdrive technique has been popularly used to alleviate the motion blur on liquid-crystal display (LCD) by shortening the response time of the liquid crystal. However, this technique requires a large frame buffer to store the previous frame as a reference. In this paper, we propose a novel block truncation coding based on the vector quantizer for the color image compression in LCD overdrive. Due to the constant output bit-rate and the low computational complexity, the proposed method is suitable for the hardware implementation in LCD overdrive. Experimental results show that the proposed method achieves higher compression ratio as well as better visual quality as compared with the conventional methods.