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From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Cc: Linux Media Mailing List <linux-media@vger.kernel.org>,
        Sakari Ailus <sakari.ailus@linux.intel.com>
Subject: Re: 3A / auto-exposure Region of Interest setting
Date: Tue, 29 Nov 2016 20:08:54 +0200
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Hi Guennadi,

(CC'ing Sakari)

On Monday 28 Nov 2016 15:18:03 Guennadi Liakhovetski wrote:
> Hi,
> 
> Has anyone already considered supporting 3A (e.g. auto-exposure) Region of
> Interest selection? In UVC this is the "Digital Region of Interest (ROI)
> Control." Android defines ANDROID_CONTROL_AE_REGIONS,
> ANDROID_CONTROL_AWB_REGIONS, ANDROID_CONTROL_AF_REGIONS. The UVC control
> defines just a single rectangle for all (supported) 3A functions. That
> could be implemented, defining a new selection target. However, Android
> allows arbitrary numbers of ROI rectangles with associated weights. Any
> ideas?

Selections could be used, possibly with an update to the API to allow indexing 
selections for a given target. We'd be missing weights though. Another option 
would be to use compound controls.

-- 
Regards,

Laurent Pinchart