ICX228AK Datasheet, PDF (9/18 Pages) Sony Corporation – Diagonal 4.5mm (Type 1/4) CCD Image Sensor for NTSC Color Video Cameras

ICX228AK
Image Sensor Characteristics Measurement Method
Measurement conditions
1) In the following measurements, the device drive conditions are at the typical values of the bias and clock
voltage conditions.
2) In the following measurements, spot blemishes are excluded and, unless otherwise specified, the optical
black level (OB) is used as the reference for the signal output, which is taken as the value of Y signal output
or chroma signal output of the measurement system.
Color coding of this image sensor & Composition of luminance (Y) and chroma (color difference) signals
Cy Ye Cy Ye
As shown in the left figure, fields are read out. The charge is
A1 mixed by pairs such as A1 and A2 in the A field. (pairs such
G Mg G Mg
as B in the B field)
B
Cy Ye Cy Ye
As a result, the sequence of charges output as signals from
A2 the horizontal shift register (Hreg) is, for line A1, (G + Cy),
Mg G Mg G
(Mg + Ye), (G + Cy), and (Mg + Ye).
Hreg
Color Coding Diagram
These signals are processed to form the Y signal and chroma (color difference) signal. The Y signal is formed
by adding adjacent signals, and the chroma signal is formed by subtracting adjacent signals. In other words,
the approximation:
Y = {(G + Cy) + (Mg + Ye)} × 1/2
= 1/2 {2B + 3G + 2R}
is used for the Y signal, and the approximation:
R – Y = {(Mg + Ye) – (G + Cy)}
= {2R – G}
is used for the chroma (color difference) signal. For line A2, the signals output from Hreg in sequence are
(Mg + Cy), (G + Ye), (Mg + Cy), (G + Ye).
The Y signal is formed from these signals as follows:
Y = {(G + Ye) + (Mg + Cy)} × 1/2
= 1/2 {2B + 3G + 2R}
This is balanced since it is formed in the same way as for line A1.
In a like manner, the chroma (color difference) signal is approximated as follows:
– (B – Y) = {(G + Ye) – (Mg + Cy)}
= – {2B – G}
In other words, the chroma signal can be retrieved according to the sequence of lines from R – Y and – (B – Y)
in alternation. This is also true for the B field.
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