Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1985-06-03
1986-05-27
Chin, Tommy P.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358 31, 358 36, 358167, H04N 514, H04N 978, H04N 521
Patent
active
045919119
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a picture filter such as a comb filter or the like used in a television receiver, which separates a video signal with a specific information from a video signal containing a plurality of signals having different information contents.
BACKGROUND ART
As will be well-known, a comb filter used in a television receiver and the like is to separate a video signal (television signal) on a frequency axis. Since such prior art separation filter on the frequency axes is not generally applicable, it performs a calculation process in such a manner that a mean value in all areas on a picture screen becomes an optimum value thus resulting in a remarkable error in a local part such as an edge of the picture.
By way of example, if the video signal for television is processed by the aforesaid comb filter, a dot interference and the like are likely to occur.
DISCLOSURE OF INVENTION
In view of the above points, this invention makes it possible to separate only a desired video signal from the characteristics in only a small part of a picture, in which the video signal is not separated on the frequency axis as in the prior art filter, but the filtering processings are performed on the amplitude level axis spaces so as to separate the video signal therefrom.
If the video signal is separated on the amplitude level axis spaces as described above, it is possible to separate only the specific video signal with accuracy more than that of the conventional one. An improvement factor of S/N ratio done by the conventional comb filter is 3.0 dB, but in accordance with the present invention, it can be improved up to 4.26 dB.
BRIEF DESCRIPTION OF DRAWINGS
FIGS. 1 and 3 are diagrams used to explain adjacent picture elements,
FIGS. 2, 4 and 5 are scattering diagrams each showing an amplitude level of the adjacent picture elements,
FIG. 6 is a conceptual systematic diagram showing one example of a picture filter according to the present invention,
FIG. 7 is a waveform diagram used to explain the operation thereof,
FIGS. 8 and 9 are graphs showing output characteristics according to the present invention,
FIG. 10 is a graph showing an output characteristic according to a conventional comb filter,
FIG. 11 is a connection diagram showing one example of an amplitude correlator,
FIGS. 12A-12E are waveform diagrams each used to explain the operation thereof,
FIGS. 13 to 15 are systematic diagrams of main parts each showing an applied example of this invention, and
FIG. 16 is a scattering diagram used to explain FIG. 15.
BEST MODE FOR CARRYING OUT THE INVENTION
For the first embodiment of this invention, a filtering process for eliminating a noise component contained in a television signal will be described with reference to FIG. 1 and the following drawings.
Picture elements when a luminance level of a video signal or television signal is sampled along a horizontal scanning direction are given as S.sub.1, S.sub.2 . . . S.sub.i in FIG. 1, an amplitude level .sub.1 of the desired picture element S.sub.i is taken on the abscissa x of FIG. 2, and an amplitude level .sub.2 of the picture element S.sub.i-1 adjacent to the picture element S.sub.i is taken on the ordinate y thereof. If the amplitude levels .sub.1 and .sub.2 between these adjacent picture elements are searched over the whole lines, the television signal has so strong correlation or correlativity between the adjacent picture elements that as shown in FIG. 2 a scattering diagram where the amplitude levels are concentrated on an axis .sub.1 = .sub.2 shown by a straight line l.sub.a is provided.
In like manner, picture elements along a vertical scanning direction are taken as S.sub.1, S.sub.2 . . . S.sub.J shown in FIG. 3. Then, if an amplitude level .sub.1 of the picture element S.sub.J and an amplitude level of the picture element S.sub.J-1 adjacent thereto are respectively searched over the whole vertical lines, in this case, the television signal has also so strong correlativity between the adjacent picture elements that as shown in FIG.
REFERENCES:
patent: 3805239 (1974-04-01), Watanabe
patent: 4141034 (1979-02-01), Maxemchuk et al.
patent: 4178609 (1979-12-01), Beutal
patent: 4241363 (1980-12-01), Maeyama et al.
Okada Takashi
Tanaka Yutaka
Chin Tommy P.
Eslinger Lewis H.
Parker Michael D.
Sinderbrand Alvin
Sony Corporation
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