Seung-Jong Choi

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.

Weighted boundary matching algorithm for error concealment in the MPEG-2 video bit stream

A novel error concealment procedure is presented for recovering the lost macroblock while decoding an erroneous MPEG-2 bitstream. The proposed weighted boundary matching algorithm (WBMA) refines the conventional boundary matching algorithm. Different from the conventional BMAs, the boundary pixels of a lost macroblock are compared with those of the previous picture located in the same position. The weighting coefficients are also adaptively adjusted to work robustly in either smooth or abruptly-changing regions. Experimental results show that the proposed algorithm outperforms the conventional algorithms, especially for the interlaced sequences having large motion or complicated textures.

Motion vector recovery for error concealment

This paper describes an error concealment algorithm to reduce the effect of channel errors in the bitstreams generated by motion compensated video coding algorithms such as MPEG. When channel errors are introduced during transmission and cannot be corrected properly, we can apply an error concealment technique to repair damaged portions of the picture by exploiting the spatial and temporal redundancies in the received and reconstructed video signal. In motion compensated video coding, if some bits are lost or received with errors, not only the current picture will be corrupted, but also errors will propagate to succeeding frames. In this paper, we analyze the effect of channel errors in MPEG-2 bitstreams, and propose an idea for recovering lost or erroneously received motion vectors. Extended luminance intensity value of the lost block is used for motion estimation at the decoder side. Simulation results show that the proposed algorithm achieves good performance in PSNR and provides good subjective image quality.

Robust noise reduction using a hierarchical motion compensation in noisy image sequences

In this paper, robust noise reduction method is proposed to stably reduce the noise by applying the adaptive temporal IIR filter using the hierarchical motion compensation. Motion vector of each pixel is obtained by hierarchical motion estimation which is reducing template block size from 8×8, to 4×4 and to 2×2. With obtained motion vector, filter weight is adjusted adaptively according to the correlation between the related pixels which is determined considering not only pixel similarity to temporal axis but also the neighboring pixel variation in spatial domain.

An ASIC design for 3D depth control of full HD resolution stereoscopic video

We present an ASIC system that adjusts the depth of a full HD resolution stereoscopic video by generating a new synthesized view video, which enables 3DTV users to control their 3D depth perception. The system consists of function core blocks including preprocessing, stereo matching, and view synthesis, and interface blocks for in/out, MCU and external memory. The system is implemented with TSMC 65nm 1P8M process. Overall die size is 6.9mm × 6.9mm and total power consumption is 1.2W during normal operation.