MT9M114_16 Datasheet, PDF (30/62 Pages) ON Semiconductor – High-Definition (HD) System-On- A-Chip (SOC) Digital Image Sensor

MT9M114: 1/6-Inch 720p High-Definition (HD) System-On-A-Chip (SOC) Dig-
ital Image Sensor
Figure 25 shows the interaction of the variables and cam_ll_inv_brightness_metric.
Figure 25: Gamma Reference Variables Against Brightness Metric
cam_ll_start_contrast_luma_percentage = 80
cam_ll_start_contrast_gradient = 50
B r ig h t
Light
cam_ll_stop_contrast_gradient = 38
cam_ll_stop_contrast_luma_percentage = 25
cam_ll_inv_brightness_metric
Low
Light
ON Semiconductor would recommend that cam_ll_start_contrast_bm is set at 100 lux
and cam_ll_stop_contrast_bm is set at 20 lux, but due to the flexibility of the MT9M114 it
is at the discretion of the user.
ON Semiconductor recommends setting cam_ll_llmode = 0x03 as this will allow the
MT9M114 to calculate both of the 19 knee point curves based on the user inputs, other-
wise the user will have to program both of the 19-knee-point curves.
Gamma Curve Selection
The MT9M114 allows the user to select between the two-curve interpolation or either of
the curves
Table 9: Gamma curve Selection
Variable
VAR(0x0F,0x0007) or
(R0xBC07)
Name
ll_gamma_select
Function
0x00= Auto curve select. The curves will interpolate based on
settings of cam_ll_start_contrast_bm and
cam_ll_stop_contrast_bm
0x01 = Contrast
curve is only used
0x02 = Noise
reduction curve is only used
MT9M114/D Rev. 11, 2/16 EN
30
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