Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1990-06-11
1992-06-02
Kostak, Victor R.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358136, H04N 713
Patent
active
051191920
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a television signal processing device which can be used for discrete transmission of images in video communications, satellite communications, CATV, and other media.
BACKGROUND ART
In conventional television signal transmission systems, the television signal is transmitted as an uncompressed signal in which no periods are compressed, or as a signal compressed by horizontal scanning line or field units. However, this latter case requires relatively large equipment because all complete signals are compressed before transmission.
Thus, in conventional time axis compression signal transmission methods, the equipment required for transmission and reception is relatively large, making use of this method difficult by any broadcasters other than large-scale broadcasting stations.
DISCLOSURE OF INVENTION
The object of the present invention is therefore to provide a signal processing method which can transmit a television signal in a short real time, and which can simplify the signal processing device required therefor.
The present invention is characterized in that the television signal is divided into horizontal scanning line units, the video signal Vn for the nth horizontal scanning period and the video signal Vn-1 for the (n-1)th horizontal scanning period in one field are compared, and when either part or all of these two signals differ, only video signal Vx for that part of the video signal Vn which differs from the video signal Vn-1 is transmitted as the video signal Vn.
Furthermore, the present invention is characterized by a television signal receiver to which is input the video signal Vn-1 for the (n-1)th horizontal scanning period and the video signal Vx for the nth horizontal scanning period in the television signal transmitted from said television signal transmitter, and reproduces the video signal Vn for the nth horizontal scanning period by calculating, mixing, overlaying, or replacing part or all of the video signal Vn-1 with the video signal Vx.
In addition, the present invention is characterized in that the video signal Vn for the nth frame or field and the video signal Vn-1 for the (n-1)th frame or field in the television signal are compared, and when either part or all of these two signals differ, only video signal Vx for that part of the video signal Vn which differs from the video signal Vn-1, or video signal Vx with the same signal before and after is transmitted in place of the video signal Vn.
With the means according to the present invention, the actual time required for transmission can be shortened and compressed because two consecutive horizontal scanning periods are compared, and instead of transmitting the entire television signal, only that part of the signals which differs is transmitted while that part which is the same is not transmitted. Thus, during the remaining period, another signal can be inserted and transmitted.
Moreover, because the means which determines the signal to be transmitted compares the television signals in two consecutive horizontal scanning periods to detect any difference, it may be achieved with a simple construction, comprising, for example, a transmitter composed of a delay line circuit and comparator and corresponding control circuits, and a receiver composed of a delay line circuit and signal insertion switcher and corresponding control circuits.
In addition, another signal can be inserted and transmitted during the period which would be used to transmit that part of the signal which is the same and does not require transmission, and the signal transmission efficiency and utilization range can be greatly increased.
With a signal processing device according to the present invention, by comparing images in frame or field units and transmitting those parts of the images which differ the data transmission volume can be reduced and the transmission time shortened even with finely patterned images because the images are compared by frame or field units and the same image and video components are removed.
REFERENCES:
patent: 3752913 (1973-08-01), Connor et al.
patent: 3767847 (1973-10-01), Haskell et al.
patent: 3940555 (1976-02-01), Amano et al.
patent: 4402010 (1983-08-01), Vogelman
patent: 4494140 (1985-01-01), Michael
patent: 4969042 (1990-11-01), Houtman et al.
Kostak Victor R.
Matsushita Electric - Industrial Co., Ltd.
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