VX6953CB datasheet(85/107 Pages) STMICROELECTRONICS

85 / 107 page

8209023 Rev 5

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VX6953CB

Image optimization

9.4

Green imbalance correction

Since ES2.0 modules, the sensor has an adaptive (four color temperature) green imbalance

correction function which can be used to reduce the green imbalance in the sensor.

Correction is carried out on the green-blue color plane only. The gain is calculated based on

a term polynomial in x and y.

In order to optimize the green imbalance correction algorithm, the coefficients for each

device are calculated under D65 lighting conditions and programmed in the NVM memory at

production test.

Settings for three other color temperatures (cool white, TL83, and horizon) are calculated

from characterization data and these are stored in the NVM memory.

The calculation of the color temperature is performed by the sensor using the color

feedback registers. Therefore it is necessary for the host to supply the sensor with the white

balance gains.

The green imbalance correction function can be used with the profile1 and profile 2 scaler

and with crop and subsampling.

The green imbalance correction is controlled by register 0xFAA3 (0x3410 is the status

0 - Disable

1 - Enable

Figure 45. Green imbalance correction plots

Original plot

Corrected plot

VX6953CB Datasheet(PDF) 85 Page - STMicroelectronics