Chan-Ho Han

Elimination of discontinuity phenomenon for repeated play of DTV stream due to playtime mismatch between ES and TS

In this paper the discontinuity phenomenon is analyzed for repeated play of finite digital television (DTV) streams and an elimination method for the discontinuity phenomenon is developed. Experimental test results using the proposed techniques show that the discontinuity problem can be eliminated effectively.

Implementation of LCD Driver Using Asymmetric Truncation Error Compensation for Mobile DMB Phone Display

Small color LCDs have been widely used in the mobile display market for the past couple of decades due to their cost effectiveness. In particular, 64K color LCDs have gained in popularity over true color LCDs due to their low power consumption and effective transmission. However, the 24-bit to 16-bit image data conversion (referred to as asymmetric data truncation) results in a colorization of the gray scale and lack of smoothness, such as pseudo edge artifacts. Thus, to solve these problems, this paper proposes and implements a simple truncation error compensation algorithm using a 1-bit lower data expansion with neighbor pixel information. In experiments, the implemented LCD driver IC is shown to correct these artifacts .

DTV lip-sync test using time indexed audio and video signals without effect on program

The paper concentrates on a lip-sync test for DTV with respect to audio and video signals using the digital bitstream. We propose a new lip-sync test method which does not affect the current program by use of the TATS (transient effect area test signals) and an additional sub-channel audio signal. The experimental result shows that the time difference between the audio and video signals can be easily measured by a captured oscilloscope waveform at any time.

Illuminance Dynamic Range Expansion using Gamma & Multi-Point Knee for Smart Phone Camera

The narrow dynamic range of most smart phone cameras is severely limited. It usually is narrower than the dynamic range of most scenes. So we proposes a illuminance dynamic range expansion using multi-point knee for smart phone camera. Such as logarithmic functions the proposed method compress the image sensor output signal. Additionally, the proposed method was merged into the gamma that is essential circuit for any cameras. To justifying multi-point knee effectiveness, we configure the control and quality evaluation system for smart phone camera module. Experimental results show that the lost information by cut off and saturated affectively reconstructed in darker and in brighter areas. Finally this methods have advantage to implement without any changing hardware for conventional smart phones.

Elimination of discontinuity phenomenon for endless loop-back playing of finite DTV stream

When using a finite DTV stream, discontinuity phenomena, such as a black or paused screen in the case of video and irregular or popping sounds in the case of audio, are generally experienced at the loop-back point. As the transmission time of the transport stream (TS) is commonly longer than the presentation time of video sequences, this causes an element stream (ES) buffer underflow at the loopback point of the TS. Therefore, this paper proposes a timematching multiplexing method for endless loop-back playing to resolve the discontinuity problem. Equations are developed to match the play times of the source, TS, and ES in consideration of the special TS transmission rate. In addition, new multiplexing methods are used to generate a TS to match the minimum matching time (MMT). Experimental results show that the MMT stream effectively eliminates any discontinuities.

MPEG postprocessing system using edge signal variable filter

We proposed the algorithm for the quantization noise reduction based on variable filter adaptive to edge signal in MPEG postprocessing system. In our algorithm, edge map and local modulus maxima in the decoded images are obtained by using 2D Mallat wavelet filter. And then, blocking artifacts in inter-block are reduced by Gaussian LPF that is variable to filtering region according to edge map. Ringing artifacts in intra-block are reduced by 2D SAF according to local modulus maxima. Experimental results show that the proposed algorithm was superior to the conventional algorithms as regards PSNR, which was improved by 0.04-0.20 dB, and the subjective image quality.

Rate control algorithm for high quality compression of static test image in digital TV system

In this paper, we propose a new algorithm for generating test bit-stream in high quality to evaluate the static image quality of DTV receiver, based on a target bit allocation in the process of rate control. In order to allocate the number of target bits, we consider the normalized complexities, which are updated or maintained according to GOP picture qualities. The proposed rate control method is suitable for the compression of static test pattern while MPEG-2 Test Model 5 is suitable for moving picture. To evaluate the performance of proposed algorithm, the test bitstream are generated by a MPEG-2 software encoder using the proposed algorithm. Experimental results show that average PSNR of the proposed method is higher than those of the conventional case. With experiment in DTV system, we have confirmed that the proposed algorithm has a stable bit rate and good video quality and it is suitable for evaluation of the DTV receiver.