We propose a new image data processing method for MUSE (Multiple Sub-nyquist Sub-sampling Encoding) signal decoding. In conventional decoding, the moving and stationary areas of the luminance signal are processed separately. Those of the chrominance signal should be processed separately as well.
However, this method requires many interpolation and sampling conversion filters and larger hardware. We have integrated these conventional filters into one 2-dimensional filter that has variable tap coefficients. This “integrated filter” has performed satisfactorily in our evaluation for the luminance signal.
Furthermore, adapting the tap coefficients of the integrated filter to the chrominance signal of the MUSE signal, an HDTV (High Definition Television) signal is reproduced by using only one 2-dimensional integrated filter.

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A noise reducer is an essential part of a MUSE decoder to reduce transmission noise caused by FM analogue transmission. Although the present MUSE system uses a noise reducer depending on the receiving signal to noise ratio, the decoded video signal to noise ratio in moving areas is still worse than in stationary areas. Furthermore our new proposal for improving picture quality of moving areas in a MUSE decoder is accomplished by extending the band width of moving areas. This improvement increases a decoded noise in moving areas, so the noise reduction in moving areas appears to be more important then ever before.
We have developed a new video noise reducer, based on shifting the d. c. level of a noisy video signal, and a median type filter for a noise detector. We have tested this new type of noise reducer using a MUSE decoder. It showed experimentally better noise reduction ratio than a conventional noise coring reducer.
To operate this noise reducer efficiently it is necessary to detect the noise level correctly, but this is impossible from a video signal. In MUSE, however, the noise level of the transmission channel can be easily detected by calculating an integral of a noise level in a prepared level of TV lines. Thus in a MUSE decoder, the new noise reducer works efficiently to reduce transmission channel noise.

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The line difference signal obtained from a 525 line 16 : 9 aspect ratio progressive camera is transmitted in the EDTV-II letter box system on the upper and lower panels as a helper signal. This line difference signal sometimes annoys viewers watching conventional televsion because of the signal's high amplitude. Many visibility-reduction methods have been proposed so far. In this paper, a correlation-based method that uses the main panel signal and the line difference signal generated by a symmetric short kernel filter is described. By using this method, the spectrum of the line difference signal is modified. We made the encoder and decoder for this method and checked the methods effects through a computer simulation. This correlation-based method is further improved and adopted as one visibility reduction method for the EDTV-II standard.

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This paper describes a new signal processing method for MUSE encoders and decoders which improves Hi-Vision pictures. Seven years have passed since MUSE was first developed as an HDTV broadcasting system. Many experiments have proved that MUSE is a practical system. Although the picture quality of MUSE is sufficient for practical use, it is still possible to improve it further. Our new signal processing method improves the picture quality of the moving areas. In addition, we have been studying how to improve picture quality of the stationary areas as well, which means extending the resolution and attenuating aliasing noise. Based on this research, we have built a new MUSE encoder and a new MUSE decoder. They are highly compatible with the conventional MUSE system.

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We completed development next generation MUSE LSI chip set. It consists of two digital processing chips. This chip set has higher quality, lower voltage (3.3 volts), lower power consumption and fewer chips. It also features a new control method for noise reduction without undesirable phenomena and improvement of moving picture quality.

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This paper dercribes the frame pulse protection system. In conventional MUSE decoders, the number of frame pulse protection is six This is one of the reasons that the picture is dameged when up-link stations are switched. According to the results of experiments studying the relationship between the reception CN ratio and the frame pulse not possible to be detected, it has been proved that is a normal situation (CN ratio is more than 17 dB), the sufficient protection number is zero. Consequently, if the protection is controlled so that it will match the reception CN ratio, picture damage when switching can be reduced.

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Differences in three dimensional noise characteristics between the current NTSC television systems and letterbox EDTV systems are studied. We showed that when pictures are displayed in an area of the identical picture height, and signal to noise ratio of the transmission signals is maintained at the same level, as in NTSC, the three-dimensional noise power spectrum of the main panel of letterbox EDTV is transformed into the low spatial frequency area with high density, although the total noise power is unchanged. On the other hand, helper signals which are multiplexed onto the black bars, the top and bottom portions of letterbox picture, generally increase the total noise power even if the multiplexing amplitude is large enough. By applying a three-dimensional weighting function, it is shown that the weighted noise power of letterbox EDTV becomes larger than that of a conventional television system. Hence, to retain the existing NTSC service area after introducing EDTV broadcasting, it will be necessary to install noise suppressing measures in the EDTV system.

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[in Japanese]

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[in Japanese]

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