Re: [RFC] New class for low level sensors controls?

[Sakari Ailus <sakari.ailus@iki.fi>]

On Tue, Sep 13, 2011 at 12:33:58PM +0200, Laurent Pinchart wrote:
> Hi Sakari,
> 
> On Thursday 08 September 2011 13:44:28 Sakari Ailus wrote:
> > On Thu, Sep 08, 2011 at 04:54:23PM +0530, Subash Patel wrote:
> > > On 09/06/2011 05:52 PM, Sakari Ailus wrote:
> > > > On Tue, Sep 06, 2011 at 01:41:11PM +0200, Laurent Pinchart wrote:
> > > > >
> > > > > Other controls often found in bayer sensors are black level
> > > > > compensation and test pattern.
> > > 
> > > Does all BAYER sensor allow the dark level compensation programming?
> > 
> > I'm not sure. I have always seen ISPs being used for that, not sensors.
> > 
> > > I thought it must be auto dark level compensation, which is done by
> > > the sensor. The sensor detects the optical black value at start of
> > > each frame, and analog-to-digital conversion is shifted to
> > > compensate the dark level for that frame. Hence I am thinking if
> > > this should be a controllable feature.
> > 
> > This is probably what smart sensors could do. If we have a raw bayer sensor
> > the computation of the optimal black level compensation could be done by
> > some of the controls algorithms run in the user space. Automatic exposure
> > probably?
> 
> Many "non-smart" raw bayer sensors implement both manual and automatic black 
> level compensation. In the first case the user programs a value to be 
> subtracted from the pixels (whether that's done in the analog or digital 
> domain might be sensor-specific), and in the second case the sensor computes a 
> mean black level value based on black lines (optically unexposed) at the top 
> of the image.

Sounds like two controls to me, right?

-- 
Sakari Ailus
e-mail: sakari.ailus@iki.fi	jabber/XMPP/Gmail: sailus@retiisi.org.uk