Thank you Pingchart.
So, V4L2_CID_DO_WHITE_BALANCE acts WB adjustment at every single time
it has issued when device is in manual WB mode like
V4L2_CID_WHITE_BALANCE_TEMPERATURE? Now I get it.
But CID still missing for white balance presets like "cloudy",
"sunny", "fluorescent"and so on.
I think some sort of menu type CID could be useful to handle them,
because WB presets differ for each devices.
Cheers,
Nate
2009/3/18 Laurent Pinchart <laurent.pinchart@xxxxxxxxx>:
> Hi Kim,
>
> On Wednesday 18 March 2009 05:32:08 Dongsoo, Nathaniel Kim wrote:
>> Hello,
>>
>> I accidently realized today that I was using white balance control in wrong
>> way.
>>
>> As far as I understand we've got
>>
>> V4L2_CID_AUTO_WHITE_BALANCE which activate auto white balance
>> adjustment in runtime, V4L2_CID_DO_WHITE_BALANCE_TEMPERATURE specifying
>> absolute kelvin value
>
> I suppose you mean V4L2_CID_WHITE_BALANCE_TEMPERATURE here.
>
>> but can't get what V4L2_CID_DO_WHITE_BALANCE is for.
>>
>> I think after issuing V4L2_CID_AUTO_WHITE_BALANCE and
>> V4L2_CID_WHITE_BALANCE_TEMPERATURE,
>> the white balance functionality works immediately. Isn't it right?
>>
>> What exactly is the button type V4L2_CID_DO_WHITE_BALANCE for? Because
>> the V4L2 API document says that "(the value is ignored)". Does that
>> mean that even we have issued V4L2_CID_AUTO_WHITE_BALANCE and
>> V4L2_CID_WHITE_BALANCE_TEMPERATURE, we can't see the white balance
>> working at that moment?
>
> V4L2_CID_AUTO_WHITE_BALANCE to enables or disables automatic white balance
> adjustment. When automatic white balance is enabled the device adjusts the
> white balance continuously.
>
> V4L2_CID_WHITE_BALANCE_TEMPERATURE controls the white balance adjustment
> manually. The control is only effective when automatic white balance is
> disabled.
>
> V4L2_CID_DO_WHITE_BALANCE instructs the device to run the automatic white
> balance adjustment algorithm once and use the results for white balance
> correction. It only makes sense when automatic white balance is disabled.
>
>> And one more thing. If I want to serve several white balance presets,
>> like cloudy, dawn, sunny and so on, what should I do?
>> I think it should be supported as menu type, but most of drivers are
>> using white balance CID with integer type...then what should I do?
>> Define preset names with kelvin number like this?
>>
>> #define WB_CLOUDY 8000
>>
>> Pretty confusing... anyone knows what should I do?
>
> Best regards,
>
> Laurent Pinchart
>
>
--
========================================================
DongSoo, Nathaniel Kim
Engineer
Mobile S/W Platform Lab.
Digital Media & Communications R&D Centre
Samsung Electronics CO., LTD.
e-mail : dongsoo.kim@xxxxxxxxx
dongsoo45.kim@xxxxxxxxxxx
========================================================
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