Jongseok Park

Image contrast enhancement based on the piecewise-linear approximation of CDF

In this paper, we present an image contrast enhancing method based on the piecewise linear approximation of the cumulative density function (CDF). Reduced hardware is required for CDF calculation, since the number of bins is greatly reduced thanks to this approximation. With the proposed method, various contrast enhancing effects can be implemented such as histogram equalization, partial or entire histogram modification.

A motion adaptive 3-D de-interlacing algorithm based on the brightness profile pattern difference

A novel motion adaptive de-interlacing algorithm is described. The accuracy of motion detection between fields is significantly improved by difference calculation with the brightness profile pattern instead of the simple pixel differences. The performance of a pure spatial interpolation is also enhanced by directional filtering combined with a hierarchical rule based detection scheme. The proposed algorithm is successfully implemented in a (H)DTV video display processor.

Video format conversions between HDTV systems

Video format conversion methods between existing or proposed HDTV (high-definition television) systems are described. The techniques necessary for this system are interlaced-to-progressive conversion (IPC), line-rate-conversion (LRC), sampling-rate-conversion (SRC), and frame-rate-conversion (FRC). An improved motion-adaptive method which consists of several modes, e.g. stationary mode, motion compensated mode, and intra-field mode, is used to perform the IPC. For LRC and SRC, a simple edge-preserving weighted linear interpolation technique is used. It has ben found that the converted images using the proposed method visually do not have any undesirable artifacts. >

A new two-layered video compression scheme for multiple applications

The authors describe a new multipurpose two-layered video compression system. The new two-layered video compression system provides the capability of encoding a higher resolution video sequence with a small modification outside the existing compression hardware. The techniques used were subsampling and expansion combined with differential pulse code modulation (DPCM) coding of the detail information lost in the subsampling process. Quadtree coding was used to encode the location of the regions to which the details were added. Simulation results of the two-layered system are included. >

Performance improvement of microcrystalline thin film silicon solar cells by back reflector with high resistivity and low absorption

In this paper, a series of microcrystalline silicon (μc-Si:H) solar cells were fabricated on different back reflectors by very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD). The results indicated that the performance of μc-Si:H solar cells strongly depended on their back reflector structures. First of all, the various Al:ZnO films with different optical and electrical properties were fabricated, and the effects on the performance of μc-Si:H solar cells as the back reflector materials were investigated. Unlike the previous studies for a-Si:H solar cells, all the μc-Si:H cells with various Al:ZnO back reflectors are showing similar I-V characteristics. However, it was interesting result that the back reflector with highest resistivity, fabricated by oxygen reactive sputtering, showed the best fill factor. As the next step, the n-μc-SiO layer with high resistivity was introduced as the new back reflector materials substituting for the conventional Al:ZnO. The optimal deposition condition for the n-μc-SiO layer was selected considering the low refractive index under 1.85, the reasonable electrical resistivity around 1E+3 Ω·cm and low absorption spectra near IR region. For the new back reflector structures, all the cell parameters were increased drastically at n-μc-SiO thicker than 300 nm, and a conversion efficiency of as high as 9.3 % (Voc: 0.501 V, Jsc: 27.4 mA/cm2, F.F: 0.68) was obtained. The performance gain for Voc and F.F was more obvious in the thicker back reflectors, suggesting that the high-resistivity n-μc-SiO layer could reduce the shunt current at the back contacts of μc-Si:H cells.

An Experimental HDTV Codec System

This work presents an experimental codec system designed for the development of a full digital high definition television. The codec system consists of (1) a computer-simulated video encoder, (2) a digital video tape remder for storing encoded data streams, (3) a hadware-implemented video decoder, and (4) hardware-implemented audio encoder/demder. The codec system provides an economic, time-efficient solution to the development of HDTV (high-definition television) receivers.