Tadashi Kasezawa

Blocking artifacts reduction using discrete cosine transform

The block discrete cosine transform (BDCT) is one of the most frequently used tools for image coding. At high compression ratios, the BDCT often brings about blocking artifacts owing to coarse quantization of its coefficients. This paper presents new algorithms for reducing the blocking artifacts. The algorithms use the BDCT itself to reduce the blocking artifacts. Moreover the block positions of the BDCT are shifted from the block positions of the BDCT in the coding process. To reduce the blocking artifacts, the BDCT coefficients are suppressed properly in response to the distribution of the BDCT coefficients in the coding process. To evaluate the performance of the algorithms, the coding model is defined and the simulation experiments are made. The experimental results show the algorithms have the effects of reducing the blocking artifacts and increasing the signal-to-noise ratio (SNR).

Improvement of Picture Quality for NTSC and PAL Systems by Digital Signal Processing

We have developed an intrafield picture quality improvement system within the existing TV standards.

DEVELOPMENT OF HDTV DIGITAL TRANSMISSION SYSTEMI THROUGH SATELLITE

A HDTV digital transmission system through satellite has been developed. This system has been designed to utilize QPSK modulation via a 36 MHz bandwidth Ku band transponder. Convolutional code and Reed-Solomon code are applied for the purpose of error protection. The system provides the transmission rate of 40 Mbps for video. A HDTV codec has been fabricated for the system. A transmission experiment has been carried out and gave excellent transmission performance. >

NTSC Y/C separation and enhancement technique with two dimensional adaptive features

A previously reported two-dimensional adaptive Y/C separation and picture enhancement technique is improved. One mode of filtering has been added to selected picture areas in which picture degradations were observed. The lack of sharpness in picture details and picture degradation because of an incorrect choice of filter characteristics have been remedied. The investigation was carried out through computer simulations and hardware implementation. >

A practical IDTV system improving picture quality for nonstandard TV signals

A practical improved-definition TV (IDTV) system is described that performs video component signal processing, automatic non-NTSC signal discrimination, and adaptively choosing between burst-locked and highly stable line-locked clocking. The system design is presented along with sample images highlighting its performance. >

Video buffer models of image division coding

The image division coding is one of the means of coding the image signals with high resolution such as HDTV. Generally the parallel processing scheme is applied to carry out the image division coding by dividing the image in several panels spatially and then employing the coding tools for each panel. However, it is necessary to distinguish the difference in coding performance between parallel and non-parallel processing schemes. This paper deals with the buffer size and buffer delay for coding due to parallel and non-parallel processing schemes. The following conclusion has been deduced through such study. For the same rate control conditions, the J division parallel processing needs the buffer size J times larger than the non-parallel processing, with the buffer delay being the same in both cases.

Digital HDTV transmission system via satellite

This paper describes a study for digital transmission system of HDTV signals through the satellite channel. This system has been designed to utilize QPSK modulation via 36 MHz bandwidth Ku band transponder. Convolutional code of rate 3/4 and (255,239) Reed-Solomon code are applied for the purpose of error protection. The system provides the transmission rate of 40 Mbps for video. In order to achieve such video date rate, we studied adaptive noise reduction filter, adaptive motion compensation and adaptive formation of blocks for DCT. This method provides a good picture quality of HDTV signals at the rate of 40 Mbps. The results of our study prove that the system is feasible. At present, we are assembling the codec which performs source coding and part of channel coding in this system. This codec can effectively confirm the performance of the basic algorithm in MPEG2.

A practical MPEG2 encoder and its techniques to provide high quality images

We have developed a practical MPEG2 encoder which encodes one channel video and two channels audio into single Transport Stream in real time. The encoder is realized in compact size, using a newly developed chip set Furthermore we have studied about composite signal processing and blocking artifacts reduction to provide high quality images. The former method handles composite video well and the latter one helps the decoder reduce blocking artifacts in scene changes and fast pans.

A Study of Scalable Image Coding for Digital Video Disk.

MPEG2をベースにしたディジタルビデオディスクの画像符号化方式として, 良好な早送り再生が可能な階層符号化の検討をシミュレーションにより行った.本稿では提案方式の検討の概要と良好な早送りの実現を可能としたデータ処理手法について述べる.