VX6854LC datasheet(90/114 Pages) STMICROELECTRONICS

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EDoF control

VX6854LC

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DocID027110 Rev 2

10.3.4

EDoF focus distance (0x0B88)

For automatic mode, the value range is 0x8000 to 0xFFFF. Whatever value is selected

within this range, automatic distance estimation will be enabled. ST recommend setting the

EDoF estimation mode to automatic mode. In this mode, when the user selects application

mode, the EDoF processing will automatically use the last estimate of the focus distance

obtained in estimation mode.

For manual mode, the value to be set in the register is the value of the distance in cm. The

range is 0x0000 to 0x7FFF. If you want to use one of the following modes, apply the

following values:

•

Super macro mode: 0 to 29 cm

•

Macro mode: 30 to 49 cm

•

Portrait: 50 to 119 cm

•

Landscape: 120 to 32767 cm

Whatever value is selected within a particular range will produce the same result. For

example, applying any value between 0 and 29 selects Super macro mode and produces

the same result in the final image.

Super macro mode only works in manual mode. Refer to Section 10.4: Super macro mode

for more detailed information.

Procedure to test distance estimation

Reference test scene: black and white chart (for example SFR chart or ISO12233), under

D65 illuminant, minimal analog gain.

Ensure that the streaming frames are correctly exposed and that the white balance gains

are written to the sensor.

Place the sensor at the minimum distance (that is, lower macro range distance) and then

move the module gradually away from the scene

The estimated distance should change according to the distances quoted below:

•

Macro mode: 30 cm

•

Portrait: 50 cm

•

Landscape: 120 cm

Note:

There is always an overlap between two consecutive modes, it might therefore be possible

that the mode switch may not be exactly done at the given boundary.

The distances quoted above are given for D65, results may vary slightly for other

illuminants. For instance, if the switch is 50 cm in Daylight, it is closer to 40 cm for tungsten

illuminants.

It’s not always possible to shoot charts at landscape distances. In this particular case, shoot

an outdoor image with objects at infinity: the estimated distance should be landscape.

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