This paper proposes a new transform coding scheme which partitions a color image composed of luminance signals and two color difference signals into variable-shape-blocks. This partition reduces interference such as mosquito noise and blocking effects. The shapes of the blocks for the above three signals accord with one another in order to reduce the amount of computation required for image segmentation and derivation of basis vectors in a KL-transform, as well as the information load related to the block shapes. This scheme attains segmentation and bit allocation for color images by minimizing the power of residual signals which are obtained through the application of a new adaptive smoothing filter, and the final mean square error in the RGB signal space. Simulation results demonstrate that this scheme improves SNR to about 2 dB more than what is attained by a JPEG Baseline System, and reproduces better images with less interference.

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We invented a coding system suitable for use in medical fields and have manufactured a prototype system to confirm its capabilities. A picture for medical use requires 10-12 bits to present its gradation, and only a few specific frames are used. Our prototype system is based on the intraframe and adaptive block size coding to reduce the amount of required processing. We add the capability to system, it is that the amount of coded data is got under the control. We confirmed that with this system enables high-definition color moving pictures with 1344×960 effective pixels to be coded and recorded on a D-2 digital VTR. We processed several kinds of pictures and found that for a compression ratio of 1 : 10.5, the SN ratio (where N is the mean-square-errors between the original picture and the decoded picture) is greater than 40 dB.

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Research and development is being widely conducted for DCT-based component TV signal coding. The most dominant TV signal, however, is the composite TV signal transmitted from a TV studio to viewers. Here, a direct composite coding scheme with a coding performance equivalent to DCT-based component coding is necessary for preventing harmful effects on picture quality and additional hardwares by a separating and composing procedure for Y/C components. For this purpose, we have developed a direct composite coding scheme based on intraframe Hadamard transform and optimized parameters for essential techniques used in this scheme. These include quantization cube, framewise precoding, high-order coefficient truncation and adaptive scanning path selection. This paper describes the coding performance for each optimized technique, as well as overall coding performance.

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Coding control schemes are developed for store-and-forward video codecs which transmit high quality pictures through low bit rate digital lines. Video transmission through easily accessable digital networks, such as ISDN and INMARSAT-A HSD service is in demand. The current transmission rates, however, are around 64 kbit/s, and are not sufficient for real-time transmission of high quality video sequences. The store-and-forward video coding approach solves this problem by using rate conversion at the expense of transmission time. Here, new techniques are required for coding rate and quality control.
This paper describes a coding rate control scheme that can be used to improve coding efficiency under variable bit rate conditions. It also describes an adaptive pre-filter that optimizes input picture resolutions as well as an edge-preserving post-filter that reduces block noise for subjective quality improvement. Each scheme is evaluated by computer simulation.

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We have implemented an Hl-rate video codec whose video quality is close to that of normal 30-frames/sec television. Until now, preprocessing has been implemented with ASICs that can manage video rates of 30 frames/sec, and actual coding has been implemented with DSPs that have a processing limit of only 15 frames/sec. From viewpoints of performance, cost, and flexibility, programmable ASICs are the best choice for implementing the Hl-rate video codecs. For compact implementation, we developed our own ASIC for the audio codec, adopted a high performance H 221 multiplexer-demultiplexer, and organized the codec system and picture quality controls under a single microprocessor. We also implemented various kinds of communication interfaces, and confirmed performance and functions by evaluating image quality and testing conformance with different vendors'codecs.

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A simultaneous transmission system for dual video signals has been developed. It can transmit two conventional TV signals through a single analog channel. The system uses an analog bandwidth compression technique. The signal to be transmitted is divided into several sub-bands in a two-dimensional spatial frequency domain, cutting out the high diagonal component. The sub-band signals then transmitted by a time division multiplex form. The encoded signal conforms to the NTSC signal format.

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This paper describes the relationship between picture quality in high definition still pictures and a set of coding parameters in the JPEG scheme. The Huffman code table and the quantization matrix is adjusted for high definition still pictures. This adjustment leads to a great improvement in picture quality, especially at a high compression ratio. The quality of a picture coded with the same coding parameters varies significantly according to the picture content. If automatic picture quality assessment and automatic selection of coding parameters suitable for each picture is enabled, program production will become very efficient.
An objective picture quality scale for high definition still pictures is developed. The scale is derived from the following three distortion factors, 1) weighted noise, 2) block distortion, and 3) mosquito noise. The objective picture quality scale and the quality of the subjective pictures obtained experimentally show good agreement.

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This paper describes a document processing design with functions that attain realtime manipulation of remote documents between different word processors and enable use of individual MMIs designed for them. These functions are obtained by realtime mechanisms that convert local documents made by word processors into ODA standard based documents. Our approach can be used for realtime document conferencing systems.

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We developed a chip set consisting of two analog ICs and two digital LSIs for serial transmission of digital video signals. It includes analog FIR filters as a part of an automatic cable equalizer that allows digital video signals to be transmitted through a coaxial cable. This chip set can transmit and receive composite NTSC/PAL, component 525/625, and wide component 525/625 digital video signals. It also includes multiplexing/demultiplexing functions for 24-bit audio and Error Detection and Handling (EDH) packets. With this chip set total digital broadcasting systems can easily be constructed.

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Digital modulation schemes for satellite broadcasting, such as ISDB (Integrated Services Digital Broadcasting), are investigated. The study must take into account the following conditions when using a 12 GHz band for digital broadcasting. The transmission scheme has to satisfy the criteria of WARC-BS. In addition, service availability must be compatible with conventional FM television services which are in use now. This is because simulcast services for digital and FM television will be necessary when digital broadcasting begins.
This paper introduces a modulation sheme and suitable tansmission rate. This study used an ISDB transmission format which includes as error correction code comprising shortened difference set cyclic code (1016, 772). Characteristics of a broadcasting satellite transponder and mass-produced satellite receiver are simulated. Results show that ISDB service in a 12 GHz band is feasible using a 40 Mbps QPSK sheme. This is confirmed by simulations and indoor experiments.

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This paper describes the development of an adaptive weighted code division multiplexing (AW-CDM) transmission system that includes a new multipath compensator. This system provides “graceful degradation” (variable picture quality with local reception conditions) of TV reception by dividing hierarchical information into spread-spectrum subchannels. Each subchannel has a different priority and, thus, a different threshold. Software simulation for the AW-CDM reveals sound performance under strong propagation. This hierarchical transmission system can be used to detect problems that occur when a digital transmission is in its threshold, thus preventing the abrupt breakdown of digital TV systems.

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OFDM (Orthogonal Frequency Division Multiplexing) is a useful digital modulation method for terrestrial digital broadcasting systems, including digital audio broadcasting. Applications of the OFDM can be expanded by combining it with a trellis coded modulation (TCM). This TCM-OFDM system can transmit a much larger number of data bits than a conventional OFDM, causing almost no reduction in bit error rate performance levels within the same frequency bandwidth. This paper describes the way a TCM-OFDM system for terrestrial digital broadcasting systems works and provides results for bit error rate performance simulations. The results under multipath conditions are described in detail.

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An amplitude limiting circuit has been developed for use in the intermediate frequency stage of a spread spectrum communication system (SSCS) receiver. This circuit allows the receiver to withstand adverse effects from single frequency interference, adjacent SSCS channel interference, and multipath and bandwidth suppression. As a result, a SSCS can be designed with a radio frequency band for short distance and low power communicaton.

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