Television – Camera – system and detail – Still and motion modes of operation
Reexamination Certificate
1996-05-28
2002-04-30
Garber, Wendy (Department: 2712)
Television
Camera, system and detail
Still and motion modes of operation
C348S234000, C348S242000, C348S253000, C348S279000, C348S702000, C358S520000, C382S167000
Reexamination Certificate
active
06380973
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an image sensing apparatus and method and, more particularly, to an image sensing apparatus and method utilizing an image sensing device, such as a CCD (charge coupled device).
A configuration of a conventional image sensing apparatus is shown in FIG.
11
. Color filters are independently provided for even-numbered field and for odd-numbered field of a solid-state image sensing device
101
using interlace scanning, as shown in FIG.
4
. Referring to
FIG. 4
, signals of Ye (yellow) and Cy (cyan) components are alternatively read out as VOUT
1
, and signals of Mg (magenta) and G (green) components are alternatively read out as VOUT
2
.
These signals outputted as VOUT
1
and VOUT
2
are applied with sample and hold processing in the sample and hold (S/H) circuits
102
and
103
shown in FIG.
11
. Thereafter, the signals enter an automatic gain controller (AGC) where the signals are amplified with automatically controlled gains, then analog-digital converted to digital signals by an analog/digital (A/D) converters
106
and
107
. The digital signals outputted from the A/D converters
106
and
107
enter memories
109
and
110
having the capacity to store television signals of one horizontal period (abbreviated as “1H”, hereinafter) and are delayed there, as well as inputted to an adder
108
where added together. The outputs from the memories
109
and
110
enter an adder
111
where they are added. As a result of the addition, luminance signals are generated.
The outputs from the adders
108
and
111
enter low-pass filters
112
and
113
, respectively, where color carrier signals are removed. The output from the low-pass filter
113
is delayed by using a memory
114
having a capacity of storing signals of 1H. The outputs from the low-pass filters
112
and
113
and the outputs from the memory
114
are luminance signals in continuous 3H. The luminance signals in continuous 3H are inputted into an aperture correction circuit
100
where high-frequency components of the inputted signals are extracted by using a high-pass filter
115
provided within the aperture correction circuit
100
. Thereafter, noises are removed from the extracted high-frequency components of the signals by a base-clipping circuit
117
, thereby an aperture correction signal in the vertical direction is produced. Meanwhile, high-frequency component of the output from the low-pass filter
113
is extracted by a high-pass filter
116
, then noises are removed from the extracted high-frequency component by a base-clipping circuit
118
, thereby an aperture correction signal in the horizontal direction is produced. These aperture correction signals in the vertical and horizontal directions are added by an adder
119
, then the signal level of the added signal is adjusted by a gain controller
120
so as to restrain the gain upon aperture correction on a low luminance signal, thus a detail (DTL) signal is generated.
Then, aperture correction is performed in such a manner that the phase of the output from the low-pass filter
113
and the phase of the DTL signal are synchronized by using a delay circuit (not-shown) and the signals are added by an adder
121
.
The luminance signals which are processed with the aperture correction is then amplified by a gain which is set to restrain the high luminance component in a knee circuit
122
. Thereafter, the luminance signal is applied with &ggr; correction by a &ggr; correction circuit
123
, further, appended with a blanking signal by a blanking signal appending circuit
124
. Furthermore, the signal is digital-analog converted to an analog signal by a digital/analog (D/A) converter
125
, passes through a low-pass filter
126
, then becomes a video luminance signal YOUT.
Meanwhile, the outputs from the memories
109
and
110
are inputted to a synchronization/interpolation circuit
127
where each of color components (here, yellow (Y), cyan (Cy), magenta (Mg) and green (G) components) of the signals are synchronized. From these respective components, returned components are removed by low-pass filters
128
to
131
. Further, a matrix operation,
(
R
G
B
)
=
(
A
11
A
12
A
13
A
14
A
21
A
22
A
23
A
24
A
31
A
32
A
33
A
34
)
(
Ye
Cy
Mg
G
)
Equation
1
is performed in a matrix operation circuit
132
to obtain R, G and B components. These R, G and B components are applied with white balance correction controlling their gains with respect to the gain of the G component by a multipliers
133
and
134
in a white balance circuit. Each of the R, G and B components which are processed with the white balance correction is added to the DTL signal outputted from the gain controller
120
in a corresponding adder
135
,
136
or
137
. Thereby, high frequency components of the R, G and B components are enhanced.
The color signals are then amplified with gains which are set to restrain high luminance component in respective knee circuits
138
to
140
, further applied with the &ggr; correction in &ggr; correction circuits
141
to
143
. Thereafter, color difference signals R-Y and B-Y are generated by performing the following operation,
(
R
-
G
B
-
Y
)
=
(
B
11
B
12
B
13
B
21
B
22
B
23
)
(
R
G
B
)
Equation
2
in a matrix operation circuit
144
. After hues of these color difference signals are corrected in a hue correction circuit
145
, high-frequency components of the corrected color difference signals are removed by low-pass filters
146
and
147
so as to become suitable to subsequent modulation. Next, the signals are modulated and appended with a burst signal in a modulation circuit, then converted to an analog signal by a D/A converter
149
. Thereafter, the signal pass through a low-pass filter
150
to be a video color signal COUT.
Further, the outputs from the respective knee circuits
138
to
140
and the respective outputs from the &ggr; correction circuits
141
to
143
are sent to respective selectors
151
to
153
. The selected signals are added with blanking signals in blanking signal appending circuits
154
to
156
, thus become red digital signals ROUT, green digital signals GOUT and blue digital signals BOUT. These digital signals are inputted to a multimedia device (not-shown), such as a computer and a printer. The selectors
151
to
153
select the signals depending upon whether the multimedia device requires the &ggr; correction or not.
However, according to the aforesaid conventional apparatus, interpolation is performed prior to the matrix operation for obtaining R, G and B components upon synchronizing respective color components of signals inputted from the CCD, frequency band of signals in the horizontal direction is narrow. This does not affect quality of an image when the signals are outputted on a television monitor. However, when the image is displayed based on the R, G and B digital signals on a display of a multimedia device, such as a computer and a printer, it causes a problem in which satisfactory resolution can not be achieved and reproduced colors are blur. The drop of the quality of resolution and blur in color are noticeable especially in a still image.
Further, an aperture correction component of luminance signal is added to R, G and B components to achieve a high quality image. However, by doing so, when a moving image is to be outputted by a printer as a still image, dark parts of the image have dazzling texture because the aperture correction signals in the low frequency component is not constrained enough and noise components are not removed satisfactorily.
SUMMARY OF THE INVENTION
The present invention has been made in consideration of the above situation, and has as its object to realize improvement in image quality, when image signals are to be outputted on a multimedia device, by switching contents of luminance signal processing and of color signal processing depending upon whether a moving image or a still image is inputted.
According to the present invention, the foregoing object is at
Canon Kabushiki Kaisha
Garber Wendy
Morgan & Finnegan , LLP
Vu Ngoc-Yen
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