Hideo Yamamoto

Comparison Between DPCM and Hadamard Transform Coding in the Composite Coding of the NTSC Color TV Signal

Since differential-pulse-code modulation (DPCM) and orthogonal transform coding (OTC) are the most fundamental methods of high-efficiency coding (bit-reduction method), it is important to clarify the basic coding characteristics of these methods and the difference between them in order to utilize the bit-reduction method effectively. This paper theoretically as well as experimentally compares the coding efficiency of a DPCM having a two-dimensional predictor with that of a two-dimensional Hadamard transform coding method (HTC) in the intrafield coding of the NTSC composite signal. The comparison evidenced that the distinctive difference in coding characteristics between DPCM and HTC depends greatly on the power level of carrier chrominance signals. That is, it is confirmed theoretically and experimentally that the coding efficiency of the HTC is far lower than that of the DPCM in the case of a signal having a high power level carrier chrominance signal such as a color-bar signal.

15/30 Mbit/s Universal Digital TV Codec Using a Median Adaptive Predictive Coding Method

This paper describes a 15/30 Mbit/s TV codec with a new approach to high-efficiency coding for TV signals, i.e., median adaptive prediction. The 15/30 Mbit/s codec, commonly applicable to NTSC, PAL, and SECAM (525/60 and 625/50) systems, uses adaptive prediction incorporating a motion-compensated interframe, an interfield, and an intrafield predictor. Its performance for digital transmission is presented. This universal codec is designed, based on CCIR recommendations concerning digital TV coding parameters for studios (Rec. 601) and general principles on long-distance digital TV transmission (Rec. 604). A field trial of 15 Mbit/s digital TV transmission using this codec between earth stations with a 30 m diameter antenna and a 5 m diameter antenna is reported.

30 Mbit/s Codec for the NTSC Color TV Signal Using an Interfield-Intrafield Adaptive Prediction

This paper proposes a new approach to the composite coding of the NTSC color TV signal, i.e., an interfield-intrafield adaptive prediction. First, concerning prediction efficiency for various moving pictures, an advantage of this coding scheme over interframe coding is clarified theoretically and experimentally. This adaptive prediction gives very good and stable performance for still to violently moving pictures. A 30 Mbit/s. codec, based on this idea, and its performance are presented. Field transmission testing through an INTELSAT satellite using this codec is also described. The picture quality is satisfactory for practically all the pictures expected in broadcast TV programs, and it is subjectively estimated to be a little better than that of the half-transponder FM transmission now employed in the INTELSAT system.

A 64 kbit/s Integrated Visual Communication System--New Communication Medium for the ISDN

Seeing-while-talking has been a dream of mankind for over a 100 years since the invention of telephone. In the past, various trials were performed in spite of the difficulty in installing the network for the actual service. However, with the progress of ISDN and the advancement of digital signal processing technology, the environment has been changing rapidly. In this paper, an integrated visual communication system is described for the enhanced communication service at 64 kbits/s, the fundamental bit rate of ISDN. The roles of state-of-theart compression of the audio and video signals are discussed and an integrated transmission method based on the priority of the information content is proposed.

Motion picture coding based on region segmentation using genetic algorithm

The purpose of this paper is to improve the coding efficiency of motion pictures by proposing a region segmentation method using the genetic algorithm (GA). In motion-compensated predictive coding, region segmentation and motion estimation are closely related to each other, and they should be performed so that the coding complexity and S/N are optimized. Their determination can be reformulated as the optimization problem of assigning the motion vectors to each block of the image. Consequently, this paper examines the data type and the processing method of GA so that the optimal region segmentation is obtained. A computer simulation using a test image was performed as an experiment, and the effectiveness of the proposed method was demonstrated.

Theoretical Comparison Between DPCM and Transform Coding Regarding the Robustness of Coding Performance for Variation of Picture Statistics

Since DPCM and transform coding are two fundamental approaches to high-efficiency (bit reduction) coding, it is important to clarify the basic coding characteristics of these approaches and the differences between them in order to utilize the high-efficiency coding method effectively. It is important to compare them not only from the standpoint of coding performance as optimized coding schemes based on the statistics of the input picture signal, but also from that of the robustness of coding performance for the variation of picture statistics to be coded. This paper theoretically compares the robustness of the coding performance of DPCM having a two-dimensional predictor with that of a two-dimensional Hadamard transform coding in an intrafield coding method of the NTSC composite signal. The comparison provides theoretical evidence that transform coding is more stable than DPCM, and this tendency is marked at lower bit rates such as 1 or 2 bits/pel, while DPCM has a higher coding performance for pictures with high autocorrelation.

Very low bit-rate coding of moving pictures for videoconference and video telephone.

テレビ電話やテレビ会議画像のビットレート低減技術について, これまでの6～1.5Mbps方式から384kbpsなどのサブレート符号化に至る技術成果をレビューし, ついで, 最近関心の高まっている64kbpsなど非常に低いレートでの動画像符号化技術の動向を紹介する.

Characteristics of Interfield and Intrafield Adaptive Prediction Coding for NTSC Composite Color TV Signals

NTSCカラーテレビ信号の新しい高能率符号化技術として, フィールド間・フィールド内適応型直接予測符号化方式を提案し, その基本特性を明らかにする.次に, この検討に基づき製作した30Mbit/sec符号化装置と同装置を用いて行った符号化実験結果, インテルサット衛星によるカラーテレビディジタル伝送実験結果を述べる.