Min-Cheol Hong

Spatially adaptive denoising algorithm for a single image corrupted by gaussian noise

In this paper, we propose a spatially adaptive denoising algorithm using local statistics for a single image corrupted by Gaussian noise. The proposed algorithm consists of two stages: noise detection and noise removal filtering. To corporate desirable properties into denoising process, local weighted mean, local weighted activity, and local maximum are defined. Using the local statistics, constraint for noise detection is defined. In addition, a modified Gaussian noise removal filter based on the local statistics is used to control the degree of noise suppression. The experimental results demonstrate the capability of the proposed algorithm.

Variable step search fast motion estimation for H.264/AVC video coder

In this paper, we propose a variable step search fast motion estimation algorithm using local statistics of neighboring motion vectors. Using the degree of correlation between neighboring motion vectors, motion search range of each macroblock is adaptively adjusted to reduce unnecessary search points. Based on the determined search range, motion vector is obtained by variable step search step. Experimental results show that comparing to fast full spiral search, fixed step, and fast variable block size motion estimation algorithms, the motion search points and computing time of proposed algorithm are dramatically reduced with acceptable loss in coding performance.

An efficient loop/post filter to reduce annoying artifacts of H.26L video coder

An efficient two-dimensional loop and post filter is addressed to reduce blocking and ringing artifacts of H.26L compressed video. A new two-dimensional regularized smoothing functional is defined and the regularization parameters controlling the degree of smoothness to four neighboring directions are determined by available information. Therefore, no information is necessary to obtain the recovered image from the compressed video. The experimental results show the capability of the proposed algorithm.

Tracking of a moving object using ultrasonic sensors based on a virtual ultrasonic image

Abstract For a mobile robot to follow a moving target, the mobile robot should have the capability of first detecting the target and then measuring its position and velocity. This paper proposes a new solution for this problem, using the virtual ultrasonic image which is simply constructed by accumulating the returned ultrasonic signal along the time axis for a certain number of measurement periods. In the virtual ultrasonic image, the slope of the trajectory of an object represents the relative speed of the object with reference to the mobile robot and a static obstacle has a trajectory whose slope is greater than a certain threshold. The mobile robot implemented for testing the performance of the proposed algorithm has shown that it follows a moving target successfully in various working environments.

Low-Power 32bit×32bit multiplier design with pipelined block-wise shutdown

This paper proposes a novel low-power 32bit×32bit multiplier with pipelined block-wise shutdown scheme. When it idles, it turns off supply voltage to reduce both dynamic and static power. It shutdowns and wakes up sequentially along with pipeline stage to avoid power line noise. In idle mode, the proposed multiplier consumes 0.013mW and 0.006mW in 0.13μm and 0.09μm technologies, respectively, and it reduces power consumption to 0.07%~0.08% of active mode. As fabrication technology becomes small, power efficiency degrades in the conventional clock gating scheme, but the proposed multiplier does not. The low-power design methodology in this paper can be easily adopted in most functional blocks with pipeline architecture.

Fast rate control algorithm in frame-layer for H.264/AVC video coding

In this paper, we propose a fast rate control algorithm in frame-layer of H.264/AVC video coding standard. We derive a statistical relation between quantization parameter (QP) and encoded bits of inter-coded blocks. In addition, new complexity estimation is defined to determine weight of complexity of current frame. Using the statistical property and the complexity updating function, we determine the amount of bits as a function of quantization parameter, so that computational cost of rate control is significantly reduced with coding gain improvement and stable buffer management. Experimental results demonstrate the capability of the proposed algorithm.

A reduced complexity loop filter using coded block pattern and quantization step size for H.26L video coder

This paper addresses a reduced complexity one-dimensional loop filter to simultaneously reduce blocking and ringing artifacts of H.26L video coder. A new one-dimensional regularized smoothing functional is defined and the regularization parameters controlling the degree of smoothness to two neighboring directions are determined by coded block pattern and quantization step size which are available both in the encoder and decoder. Therefore, no information is necessary to obtain the recovered image from the compressed video. The experimental results show the capability of the proposed algorithm.

Video stabilization algorithm using a moving alpha-trimmed mean filter window

In this paper, a fast video stabilization approach is presented to remove the unwanted camera vibration in video sequence. The proposed method first tracks good features from video sequence by using Kanade-Lucas-Tomasi method, then estimates the affine transform parameters using RANSAC algorithm. Each consecutive frames parameters are summed up to form the accumulated trajectory and a moving alpha-trimmed mean filter is used to achieve the smoothed motion. Experimental results show the capability of the proposed algorithm.

Fast and efficient Gaussian noise image restoration algorithm by spatially adaptive filtering

In this paper, we propose a spatially adaptive noise removal algorithm using local statistics that consists of two stages: noise detection and removal. To corporate desirable properties into denoising process, the local weighted mean, local weighted activity, and local maximum are defined. With these local statistics, the noise detection function is defined and a modified Gaussian filter is used to suppress the detected noise components. The experimental results demonstrate the effectiveness of the proposed algorithm.

Adaptive rate control scheme for real-time H.264/AVC video coding

The purpose of this paper is to improve allocation of the number of bits without skipping the frame by accurately estimating the target bits in H.264/AVC rate control. In our scheme, we propose an enhancement method of the target frame rate based H.264/AVC bit allocation. The enhancement uses a frame complexity estimation to improve the existing MAD complexity measurement. Simulation results show that the proposed rate control scheme achieves time saving of more than 99% over existing rate control algorithm. Nevertheless, PSNR and bit rate were almost same as the performances.