On Wed, Jan 04, 2012 at 11:06:13PM +0100, Sylwester Nawrocki wrote: > Hi Sakari, > > On 01/04/2012 10:24 PM, Sakari Ailus wrote: > >>>>> I don't quite understand the purpose of the do_white_balance; the > >>>>> automatic white balance algorithm is operational until it's disabled, > >>>>> and after disabling it the white balance shouldn't change. What is the > >>>>> extra functionality that the do_white_balance control implements? > >>>> > >>>> Maybe DO_WHITE_BALANCE was inspired by some hardware's behaviour, I don't > >>>> know. I have nothing against this control. It allows you to perform > >>>> one-shot white balance in a given moment in time. Simple and clear. > >>> > >>> Well, yes, if you have an automatic white balance algorithm which supports > >>> "one-shot" mode. Typically it's rather a feedback loop. I guess this means > >>> "just run one iteration". > >>> > >>> Something like this should possibly be used to get the white balance > >>> correct by pointing the camera to an object of known colour (white > >>> typically, I think). But this isn't it, at least based on the description > >>> in the spec. > >> > >> Then either the spec is incorrect, or I'm mistaken. My understanding of the > >> DO_WHITE_BALANCE control is exactly what you described. > > > > This is what the spec says: > > > > "This is an action control. When set (the value is ignored), the device will do > > a white balance and then hold the current setting. Contrast this with the > > boolean V4L2_CID_AUTO_WHITE_BALANCE, which, when activated, keeps adjusting the > > white balance." > > > > I wonder if that should be then changed --- or is it just me who got a different > > idea from the above description? > > Only you ? :-) Same as Laurent, I understood this control can be used to do white > balance after pointing camera to a white object. Not sure if the description > needs to be changed. Definitely it needs to be changed. Who will submit the patch? :-) -- Sakari Ailus e-mail: sakari.ailus@xxxxxx jabber/XMPP/Gmail: sailus@xxxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
