Television – Camera – system and detail – With single image scanning device supplying plural color...
Reexamination Certificate
1998-09-28
2003-07-15
Vu, Ngoc-Yen (Department: 2612)
Television
Camera, system and detail
With single image scanning device supplying plural color...
C348S220100, C348S237000, C348S280000, C382S167000
Reexamination Certificate
active
06593964
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to single-plate color solid-state image pickup apparatus in which the resolution characteristics of hue and luminance are not debased when all the pixels are read out and yet color generation can be performed by a single line where lines are skipped (thinned out) when read out.
Color filter array constructed as shown in
FIGS. 1A
,
1
B,
1
C are known as using complementary color filters of the generally used type to produce color signals when all pixels of the image-pickup device are sequentially read out in a single-plate color solid-state image pickup apparatus. In this color filter array, four color filters Ye, Mg, Cy and G are arranged in the manner of a mosaic.
FIG. 1A
shows the signal processing mode for producing CR signal;
FIG. 1B
shows the signal processing mode for producing CB signal; and
FIG. 1C
shows the signal processing mode for producing YL signal. It should be noted that CR signal corresponds to (R−Y) color-difference signal, CB to (B−Y) color-difference signal, and YL to Y signal. Color signals (RGB) can be produced by combining these three signals. The numerals
1
,
2
,
3
and
4
in
FIG. 1B
correspond to Ye, Mg, Cy and G, respectively, representing their order of arrangement which may be considered as the like of the array shown in
FIGS. 1A and 1C
. The complementary color filters Ye, Mg and Cy are the filters for indicating the components of Ye=R+G, Mg=R+B and Cy=B+G, respectively. Further, the CR signal, CB signal and YL signal can be expressed as in the following equations (1), (2) and (3):
CR
=(
Ye+Mg
)−(
Cy+G
)=2
R−G
(1)
CB
=(
Cy+Mg
)−(
Ye+G
)=2
B−G
(2)
YL=Ye+Mg+Cy+G=
2
R+
3
G+
2
B
(3)
A description will now be given with respect to the mode of producing CR signal as shown in FIG.
1
A. For the first pixel of the first line of
FIG. 1A
, CR signal of the first pixel can be produced by the signal processing of (Ye
11
+Mg
21
)−(Cy
12
+G
22
). CR signal of the second pixel is produced by the signal processing of (Ye
13
+Mg
23
)−(Cy
12
+G
22
). By sequentially forming CR signals of the pixels of third and after in a similar manner, all the CR signals for the first line can be provided onto the line. At the first pixel of the third line, CR signal of the first pixel can be produced in a similar manner as in the first line by the signal processing of (Ye
32
+Mg
42
)−(Cy
31
+G
41
). A similar signal processing can be performed for the second and third pixels of the third line and also for other odd-number lines to produce CR signals onto all the odd-number lines. CR signal of the even-number lines, for example of the first pixel of the second line, can be produced by interpolating between the CR signals of above and below, i.e., the first pixel of the first line and the first pixel of the third line. It should be noted that, in the figures, an interpolation for producing a signal is represented by its abbreviation “INT” and the direction of such interpolation is indicated by arrow. CR signals corresponding to other even-number lines can be also produced by vertically interpolating in a similar manner. Production is thus possible of the CR signals corresponding to all the pixels. Further, the CB signals and YL signals can be produced by performing signal processing as shown in
FIGS. 1B and 1C
.
Shown in
FIG. 2
is a block diagram of a digital circuit for processing signal to produce CR, CB and YL signals, the operation of which will be described below with reference to
FIGS. 1A
,
1
B,
1
C. First, addition of lines (vertical addition) is performed by adding together and averaging input signal SigIN and a signal obtained by delaying input signal SigIN by 1H (line). In particular, the line addition is sequentially performed for example as first line+second line, second line+third line. Next, to produce YL signal (FIG.
1
C), signal A derived from such line addition and signal B derived from delaying of signal A by 1D (data) are added together and averaged to obtain a horizontally added signal which becomes YL signal.
To produce CR signal (
FIG. 1A
) and CB signal (
FIG. 1B
) signal (A−B) derived from subtraction from the line added signal A of signal B which is obtained by delaying signal A by 1D (data), and signal (B−A) derived from the inverted subtraction thereof are alternately selected for each 1D (data). Thus obtained signal is CR/CB signal. The CR/CB becomes CR signal for the odd-number lines and CB signal for the even-number lines. Accordingly, a signal obtained by adding together and averaging (vertically interpolating) CR/CB signal and one derived from 2H-delay of CR/CB signal, and a signal obtained by delaying CR/CB signal by 1H can be alternately selected for each 1H to form CR signal and CB signal.
A description will be given below by way of
FIG. 3
with respect to a known system for producing color signals by using a mixed complementary color filter when all pixels of the image-pickup device are sequentially read out similarly as the above. A mixed complementary color filter array is formed by arranging four color filters Wr, Gr, Gb and Wb in the manner of a mosaic as shown in
FIGS. 3A
,
3
B,
3
C.
FIG. 3A
shows the signal processing mode for producing CR signal;
FIG. 3B
shows the signal processing mode for producing CB signal; and
FIG. 3C
shows the signal processing mode for producing YL signal. It should be noted that a disclosure has been made in Japanese Patent Publication No.Hei-1-42192 with respect to the mixed complementary color filter.
The numerals
1
,
2
,
3
and
4
in
FIG. 3B
correspond to Wr, Gr, Gb and Wb, respectively, representing their order of arrangement which may be considered as the like of the array shown in
FIGS. 3A and 3C
. The mixed complementary color filters Wr, Gr, Gb and Wb are the filters possessing the components of Wr=Ye+Mg, Gr=Ye+G, Gb=Cy+G and Wb=Cy+Mg, respectively. Further, from Ye=R+G, Mg=R+B and Cy=B+G, the signals CR, CB and YL can be expressed by the following equations (4), (5) and (6):
CR
=(
Ye+Mg
)−(
Cy+G
)=
Wr−Gb=
2
R−G
(4)
CB
=(
Cy+Mg
)−(
Ye+G
)=
Wb−Gr=
2
B−G
(5)
YL=Ye+Mg+Cy+G=Wr+Gb=Wb+Gr=
2
R+
3
G+
2
B
(6)
A description will now be given with respect to the mode of producing CR signal as shown in FIG.
3
A. For the first pixel of the first line of
FIG. 3A
, CR signal of the first pixel can be produced by the signal processing of (Wr
11
−Gb
12
). CR signal of the second pixel is produced by the signal processing of (Wr
13
−Gb
12
). By sequentially forming the CR signals of the pixels of third and after in a similar manner, all the CR signals of the first line can be provided onto the line. At the first pixel of the third line, CR signal of the first pixel can be produced in a similar manner as in the first line by the signal processing of (Wr
32
−Gb
31
). By performing a similar signal processing for the second and third pixels of the third line and also for other odd-number lines, CR signal can be provided onto all the odd-number lines. CR signal of the even-number lines, for example of the first pixel of the second line, can be produced by interpolating between the CR signals of above and below, i.e., the first pixel of the first line and the first pixel of the third line. The CR signals corresponding to other even-number lines can be also produced by vertical interpolation in a similar manner. Production is thus possible of the CR signals corresponding to all the pixels. Further, the CB signals and YL signals can be produced by performing signal processing as
Armstrong Westerman & Hattori, LLP.
Olympus Optical Co,. Ltd.
Vu Ngoc-Yen
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