MT9P001 Datasheet, PDF (36/48 Pages) ON Semiconductor – CMOS Digital Image Sensor

MT9P001: 1/2.5-Inch 5Mp Digital Image Sensor
Features
Black level calibration is normally done separately for each color channel, and different
channels can be using different sample or adjustment methods at the same time.
However, because both Green1 and Green2 pixels go through the same signal chain, and
Red and Blue pixels likewise go through the same signal chain, it is expected that the
chosen offset for these pairs should be the same as long as the gains are the same. If
Lock_Green_Calibration is set, and (Green1_Analog_Gain = Green2_Analog_Gain) and
(Green1_Analog_Multiplier = Green2_Analog_Multiplier), the calculated or user-speci-
fied Green1_Offset is used for both green channels. Similarly, if Lock_Red/Blue_Calibra-
tion is set, and (Red_Analog_Gain = Blue_Analog_Gain) and (Red_Analog_Multiplier =
Blue_Analog_Multiplier), the calculated or user-specified Red_Offset is used for both the
red and blue channels.
The current values of the offsets can be read from the Green1_Offset, Red_Offset,
Blue_Offset, and Green2_Offset registers. Writes to these registers when Manual_BLC is
set change the offsets being used. In automatic BLC mode, writes to these registers are
effective when manual mode is re-entered. In Manual_BLC mode, no sampling or
adjusting takes place for any color.
Digital Black Level Calibration
Digital black level calibration is the final calculation applied to pixel data before it is
output. It provides a precise black level to complement the coarser-grained analog black
level calibration, and also corrects for black level shift introduced by digital gain. This
correction applies to the active columns for all rows, including dark rows.
Test Patterns
Note:
The MT9P001 has the capability of injecting a number of test patterns into the top of the
datapath to debug the digital logic. With one of the test patterns activated, any of the
datapath functions can be enabled to exercise it in a deterministic fashion. Test patterns
are enabled when Enable_Test_Pattern is set. Only one of the test patterns can be
enabled at a given point in time by setting the Test_Pattern_Mode register according to
Table 16. When test patterns are enabled the active area will receive the value specified
by the selected test pattern and the dark pixels will receive the value in Test_Pat-
tern_Green for green pixels, Test_Pattern_Blue for blue pixels, and Test_Pattern_Red for
red pixels.
ON Semiconductor recommends turning off black level calibration (BLC) when Test
Pattern is enabled, others wise some of the test patterns will not be properly output.
Table 16:
Test Pattern Modes
Test_Pattern_Mode
0
1
2
3
4
5
6
7
8
Test Pattern Output
Color field (normal operation)
Horizontal gradient
Vertical gradient
Diagonal gradient
Classic test pattern
Walking 1s
Monochrome horizontal bars
Monochrome vertical bars
Vertical color bars
MT9P001_DS Rev. L 4/15 EN
36
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