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2-1 -3. Shooting Method
The colour filter arrangements that are used for the CCD in
this system are shown in Fig. 2-4. The arrangement of 8
picture elements enclosed by the bold line becomes one
block. That block is lined horizontally and vertically. This
system mixes 2 adjacent picture elements in the vertical
direction when reading signal charges. In other words,
H1 +H2, H3+H4 . . . compose lines respectively are read out as
shown in Fig. 2-4. At this time, the signal compositions are
as follows :
(H1 +H2) line __,,. Mg+ Ye, G+Cy, Mg+ Ye, G+Cy 00 •
(H3+H4) line .... ., ,. G+Ye, Mg+Cy, G+Ye, Mg+Cy 00 •
And the same signal is repeated every 2 lines.
Here, an average of each line is drawn considering that
Mg=R+B, Ye=R+G, Cy=B+G :
(H1 +H2) line .... ., ,. {(R+B+R+G)+(G+B+G)}/2=(2R+3G+2B)/2
(H3+H4) line .... ., ,. {(G+G+R)+(R+B+B+G)}/2=(2R+3G+2B)/2
With this, each line becomes the same value. In this
system, by letting the CCD signal output pass through the
(Y)
LPF, each line is equalised and is used for the luminance
signal. Since the Y signal is proportional to 2R+3G+2B,
B is reproduced brighter than reality, in comparison to the
formula y (=0.3R+0.59G+0. 1 1 B) used in the specification
for televisions. But this is not a problem for actual usage.
On the other hand, since each line repeats the same signal
every 2 picture elements, it is the equivalent of a conversion
at the rate of the special frequency of the 2-picture element
cycle (in this system, 7.2 M Hz).
When seeking the level difference of the neighbouring
picture elements of the modulated component with the BPF
or the sample hold, it becomes :
(H1 +H2) line __,,. {(R+B+R+G)-(G+B+G)}=2R-G
(H3+H4) line __,,. {(G+G+R)-(R+B+B+G)}=G-2B
Thus, 2R-G and G-2B components can be gained every 2
lines respectively.
In this system, this is used as the chroma (C) signal.
However, it is impossible to get each r, g and b component
required to create the chroma signal. Therefore, the
u n - obtained chroma signals are compensated for by the
signals taken from 1 line before. For example, in the
(H3+H4) line, each r, g and b component can be obtained
by 2R-B of the (H1 +H2) line. Therefore, the 1 H delay line is
absolutely necessary to this system. At the same time, i n
order t o obtain r, g and b from 2R-G and G-2B, the following
formulas are used.
r __,,. (2R-G)+0.1 2Y=2.24R-0.64G+0.24B
g .... ., ,. Y-(2R-G)+(G-2B)=5G
b .... ., ,. -(G-2B)+0.2{Y-(2R-G)}=2.4B-0.2G
(However, when Y=2R+3G+2B)
Both r and b are mixed with other chroma components, but
this is not a problem for actual usage.
{H1
H2
ODD
{H3
FIELD
H4
ODD
H5
FIELD
H6
2-2. IC CONFIGURATION
This system mainly consists of the following I Cs:
IC951 (ICX059AK)
IC91 7 (CXA1 390AR)
IC91 4 (CXA 1 391 R)
IC91 2 (CXA 1 392R)
IC91 9 (CXL5504M)
IC91 3 (CXL 1 51 7N)
And, the ICs required for the above IC functions are:
IC91 8 (CXD1 250N)
IC91 6 (CXD1 256R)
IC91 5 (CXD1 1 59Q)
IC91 1 (MSM6524GS)
- 4- 1 2 -
a
b
d
e
c
Mg
G
Mg
G
Mg
Ye
Cy
Ye
Cy
Ye
G
Mg
G
Mg
G
Ye
Cy
Ye
Cy
Ye
Mg
G
Mg
G
Mg
Ye
Cy
Ye
Cy
Ye
Fig. 2-4. Colour Fiiter
CCD imager
CDS, AGC and colour separa
tion, etc.
Gamma correction, chroma syn
chronisation, white balance, ma
trix, etc.
Balanced
modulator,
correction, etc.
Broad band 1 H delay line
Narrow band 1 H delay line
V driver
Timing pulse generator
Sync signal generator
Electronic volume
}
EVEN
FIELD
}
EVEN
FIELD
aperture
3
x
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