Television – Image signal processing circuitry specific to television – Chrominance-luminance signal separation
Reexamination Certificate
1998-06-09
2003-12-23
Harvey, David E. (Department: 2614)
Television
Image signal processing circuitry specific to television
Chrominance-luminance signal separation
Reexamination Certificate
active
06667776
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to a video signal processor.
BACKGROUND OF THE INVENTION
Conventional video signal processors have separately a noise reduction (hereinafter referred to as NR) circuit for a baseband video signal supplied by reproducing a video tape and a luminance/chrominance separation (hereinafter referred to as Y/C separation) processing circuit.
Referring now to
FIGS. 1 and 2
, a conventional video signal processor will be briefly described.
FIG. 1
shows a conventional NR processing circuit adapted for processing such baseband video signals. While,
FIG. 2
shows a conventional inter-frame non-correlation component removing circuit for performing a motion-adaptive Y/C separation for such composite video signals.
A baseband video signal reproduced by VTRs, laser disc players and the like is supplied to an input terminal
101
. The baseband video signal is supplied to an A/D converter
103
. The A/D converter
103
converts the input video signal in an analog format into a corresponding digital format signal. Then following video signal processing will be carried out in digital manner. Thus if the following video signal processing is carried out in a analog manner, the A/D converter
103
will be deleted. The video signal in this stage will be referred to as a
0
H video signal hereinafter for distinguishing from other video signals as described later.
The
0
H video signal is supplied to a first line memory
105
. The first line memory
105
delays the
0
H video signal by one line period. The delayed video signal will be referred to as a
1
H video signal hereinafter. The
1
H video signal is supplied to a second line memory
107
.
The second line memory
107
delays the
1
H video signal by additional one line period. The delayed video signal from the second line memory
107
will be referred to as a
2
H video signal hereinafter.
The
0
H video signal, the
1
H video signal and the
2
H video signal are processed by band-pass filters (BPFS)
109
,
111
and
113
for extracting a prescribed frequency band with a center frequency of a 7.16 MHz, respectively.
The
0
H video signal, the
1
H video signal and the
2
H video signal each having the prescribed frequency band are supplied to a common inter-line non-correlation component extractor
115
for extracting a non-correlation component among the three video signals. The extracted inter-line non-correlation components are then supplied to a gain adjuster
117
.
The gain adjuster
117
adjusts the gain of the inter-line non-correlation component.
The output of the gain adjuster
117
can be assumed as a noise component. The output of the gain adjuster
117
is thus subtracted from the
1
H video signal at the subtractor
119
for obtaining an NR processed signal. The NR processed video signal is output through an output terminal
121
.
In the conventional inter-frame non-correlation control circuit as, as shown in
FIG. 2
, a composite video signal in a form of an NTSC system recorded video signal is input to an input terminal
201
. The composite video signal is then supplied to an A/D converter
203
. The A/D converter
203
converts the input video signal in an analog format into a corresponding digital format signal. The video signal in this stage will be referred to as a
0
H video signal hereinafter for distinguishing from other video signals as described later.
The
0
H video signal is supplied to a first line memory
205
. The first line memory
205
delays the
0
H video signal by one line period. The delayed video signal will be referred to as a
1
H video signal hereinafter. The
1
H video signal is supplied to a second line memory
207
.
The second line memory
207
delays the
1
H video signal by additional one line period. The delayed video signal from the second line memory
207
will be referred to as a
2
H video signal hereinafter.
The
0
H video signal, the
1
H video signal and the
2
H video signal are processed by band-pass filters (BPFS)
209
,
211
and
213
for extracting a prescribed frequency band with a center frequency of a 3.58 MHz or a color sub-carrier frequency, respectively.
The
0
H video signal, the
1
H video signal and the
2
H video signal each having the prescribed frequency band are supplied to a common inter-line non-correlation component extractor
215
for extracting a non-correlation component among the three video signals. The extracted inter-line non-correlation components are then supplied to an adder
228
through the non-linear filter
227
, and wherein the inter-line non-correlation components are added with three-dimensional chrominance components C
3
as described later. Then the added signal is supplied to a subtractor
219
.
The subtractor
219
subtracts the output signal of the non-linear filter
217
from the
1
H video signal. Thus a two-dimensional luminance signal Y
2
is obtained from the subtractor
219
and then supplied to one input terminal of a mixer
223
.
The
1
H video signal is also supplied to an inter-frame non-correlation signal remover
225
wherein the inter-frame Y/C separation is performed on the
1
H video signal. A three-dimensional luminance signal Y
3
is thus obtained from the inter-frame non-correlation signal remover
225
and supplied to another input terminal of the mixer
223
. While a three-dimensional chrominance signal C
3
obtained from the inter-frame non-correlation signal remover
225
is supplied to another input terminal of the adder
228
, and wherein the three-dimensional chrominance signal C
3
is added with the above-mentioned inter-line non-correlation components.
The mixer
223
mixes the two-dimensional luminance signal Y
2
from the subtractor
219
and the three-dimensional luminance signal Y
3
from the inter-frame non-correlation component remover
225
in the ratio defined by a motion signal which is obtained separately as described later. A mixed luminance signal Y is output through an output terminal
227
.
Such a conventional NR circuit, as shown in
FIG. 1
, and such a conventional Y/C separation circuit, as shown in
FIG. 2
, are individually dedicated for a sole use of the NR and the Y/C separation. Thus VTRs must incorporate independent units of such an NR circuit and a Y/C separation circuit.
As a result, conventional VTRs experience an increase of circuit scale, thus causing also increases of costs.
Here, the Japanese Patent Application Tokkai-Hei 4-347991 discloses a inter-frame non-correlation removing (or extracting) circuit, or a video signal processing circuit for separating a luminance signal from a composite video signal.
However, in the conventional inter-frame non-correlation removing (or extracting) circuit disclosed in the Japanese Patent Application it is required that LPFs in a luminance signal extraction system and BPFs in a chrominance signal extraction system are constructed in a complementary relationship with each other for preserving a flat frequency characteristics. However such a requirement has a drawbacks that it not only restricts design conditions, but also causes the increases of circuit scale and costs of apparatus.
Further, in the conventional inter-frame non-correlation removing (or extracting) circuit disclosed in the Japanese Patent Application comb-filters for separating luminance signals is constructed in a non-cyclic type. Thus there is a drawback that it cannot achieve a sufficient S/N ratio.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention is to provide a video signal processor which is not only reduced in the circuit scale but also improved in precision of NR operation, by constructing a single unit which is operable in common for the NR operation and the Y/C separation.
It is another object of the present invention to provide a video signal processor which is able to not only extract a luminance signal with a flat horizontal frequency characteristics by a simple circuit configuration, but also improve the S/N ratio in a luminance signal low band component, in particular, a video signal proc
Ikeda Kazumasa
Kawabata Hitoshi
Mazda Naoki
Sumiyoshi Masatoshi
Tanaka Seiichi
Harvey David E.
Kabushiki Kaisha Toshiba
Pillsbury & Winthrop LLP
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