Seung Jin Baek

Fast Mode Decision Using All-Zero Block Detection for Fidelity and Spatial Scalable Video Coding

In scalable video coding (SVC) as an extension of H.264/advanced video coding (AVC), a computationally expensive exhaustive mode decision is employed to select the best coding mode for each macroblock (MB). In order to reduce computational complexity, we propose a fast mode decision algorithm for SVC which uses an all-zero block (AZB) detection. Based on the empirical analysis of the inter-layer correlation of the AZB, the MB at the enhancement layer (EL) is predicted whether to be the AZB. Then, only predicted MBs are examined by the AZB detection algorithm. Since the mode decision can be terminated by detecting the AZB, we determine the processing order of the candidate modes at the EL in order to terminate the mode decision in the early stage. The proposed algorithm can be combined with other conventional fast mode decision methods in order to further reduce the computational complexity of those methods. Experimental results show that the proposed algorithm can significantly speed up the encoding process, especially for low bit-rate video sequences, without deteriorating the coding efficiency of SVC.

Eyeball model-based iris center localization for visible image-based eye-gaze tracking systems

In general, the visible image-based eye-gaze tracking system is heavily dependent on the accuracy of the iris center (IC) localization. In this paper, we propose a novel IC localization method based on the fact that the elliptical shape (ES) of the iris varies according to the rotation of the eyeball. We use the spherical model of the human eyeball and estimate the radius of the iris from the frontal and upright-view image of the eye. By projecting the eyeball rotated in pitch and yaw onto the 2-D plane, a certain number of the ESs of the iris and their corresponding IC locations are generated and registered as a database (DB). Finally, the location of IC is detected by matching the ES of the iris of the input eye image with the ES candidates in the DB. Moreover, combined with facial landmark points-based image rectification, the proposed IC localization method can successfully operate under natural head movement. Experimental results in terms of the IC localization and gaze tracking show that the proposed method achieves superior performance compared with conventional ones.

Selective inter-layer residual prediction for SVC-based video streaming

The scalable video coding (SVC) standard adopts the inter-layer residual prediction (ILRP) algorithm to encode the residual signal of the enhancement layer (EL). The ILRP reduces the number of bits required for encoding the residual signal but incurs excessive encoding time. In this paper, we propose a fast encoding algorithm for SVC-based video streaming. In this algorithm, the ILRP is selectively applied to the coding modes depending on their Lagrangian rate-distortion costs. Experimental results show that the proposed algorithm can reduce computational complexity with negligible video quality degradation and bitrate increments.

Practical error concealment strategy for video streaming adopting scalable video coding

The scalable video coding (SVC) standard adopts four post-processing error concealment (EC) methods as a non-normative tool in order to conceal a lost picture in transmission. In this paper, we first introduce an error tracking model with which the concealment error and propagation error can be estimated. Then, we analyze the four EC methods using the error tracking model. Until now, there have been few studies on how to conceal SVC bitstream corrupted by burst errors. Based on the results of the error analysis, we propose a selection-based EC strategy to conceal burst errors for SVC bitstream. In the proposed strategy, one of the four EC methods is adaptively selected such that the visual degradation is minimized for each lost picture. The experimental results show that the proposed EC strategy can improve the EC performance without increasing the computational complexity. Moreover, the proposed strategy does not require any modification of the conventional SVC codec since it utilizes only the EC methods adopted in the standard.

Estimation-Based Interlayer Intra Prediction for Scalable Video Coding

The scalable video coding (SVC) standard adopts a simple interlayer intra prediction (ILIP) method for encoding scalable video sequences. In the conventional ILIP, a prediction signal for the macroblock (MB) of the enhancement layer (EL) is obtained by simply upsampling the colocated block of the base layer (BL). We propose an improved ILIP method by generalizing the original one adopted in the SVC standard. In the proposed ILIP method, the MB of the EL is predicted using all MBs of the BL. Experimental results show that the proposed algorithm can reduce the bit rate by 1.91% to 6.44%, as compared with the conventional ILIP, while the average PSNR is not decreased.

Improved pupil center localization method for eye-gaze tracking-based human-device interaction

This paper presents an improved pupil center (PC) localization method for eye-gaze tracking. In the proposed method, an input infrared eye image is repeatedly binarized with a finite number of different thresholds to produce a stack of binary images. Among all the blobs, which are groups of connected binary pixels in the binary image stack, we find a blob whose shape is the most similar to pupil, in terms of the size, the aspect ratio, the moments, and the circularity. Consequently, the centroid of the final resultant blob is regarded as the PC location. Experimental results show that the proposed method outperforms conventional ones.

A hybrid method for whole-frame error concealment

In this paper, a novel hybrid method for whole-frame error concealment is proposed. The proposed method effectively combines results of various EC methods using the Kalman filter algorithm. Experimental results demonstrate that the proposed method improves PSNR performance with acceptable additional bits.

A novel iris center localization method based on the spherical eyeball rotation model for human-device interaction

This paper presents a novel iris center (IC) localization algorithm for human-device interaction (HDI). In the proposed method, many different IC locations and their corresponding iris boundaries (IBs) are first registered as a database. Using the database, IB matching is performed to locate the IC. Experimental results show that the proposed algorithm outperforms the conventional ones especially when the iris is located at the corners of the eye.

Perceptual quality-complexity optimized video playback on handheld devices

With growing popularity and richer functionality of handheld devices such as PDAs and smart phones, users can enjoy a variety of videos in almost anyplace and anytime. However, since the battery-consumed devices are constrained by limited resources, decoding of full scale video in terms of the frame size and rate is not efficient for handheld devices. This paper presents a low complexity and perceptual quality optimized video playback algorithm. In the proposed method, the best combination of the frame size and rate is determined to maximize the user perceived quality subject to given complexity constraint. According to the selected frame size and rate, the proposed H.264 decoder performs the spatio-temporal rescaling during video playback. Experimental results show that the proposed method reduces the computational complexity significantly while maintaining the acceptable video quality for video playback on handheld devices.

Frame-adaptive deblocking filter for H.264/AVC

This paper presents a frame-adaptive deblocking filter that can improve the coding efficiency of the H.264/AVC standard. In the proposed deblocking scheme, the optimal filter coefficients are found by minimizing the mean square error between the block edge in each decoded frame and that in the corresponding original frame. Experimental results show that the proposed deblocking scheme can increase the average PSNR by up to 0.29 dB in the I only coding structure and 0.13 dB in the IPPP coding structure, as compared to the H.264/AVC standard.