Hi.
On 09/26/2012 12:42 AM, Sakari Ailus wrote:
On Wed, Sep 26, 2012 at 12:14:36PM +0530, Prabhakar Lad wrote:
Hi All,
On Sun, Sep 23, 2012 at 4:56 PM, Prabhakar Lad
<prabhakar.csengg@xxxxxxxxx> wrote:
Hi All,
The CCD/Sensors have the capability to adjust the R/ye, Gr/Cy, Gb/G,
B/Mg gain values.
Since these control can be re-usable I am planning to add the
following gain controls as part
of the framework:
1: V4L2_CID_GAIN_RED
2: V4L2_CID_GAIN_GREEN_RED
3: V4L2_CID_GAIN_GREEN_BLUE
4: V4L2_CID_GAIN_BLUE
5: V4L2_CID_GAIN_OFFSET
I need your opinion's to get moving to add them.
I am listing out the gain controls which is the outcome of above discussion:-
1: V4L2_CID_GAIN_RED
2: V4L2_CID_GAIN_GREEN_RED
3: V4L2_CID_GAIN_GREEN_BLUE
4: V4L2_CID_GAIN_BLUE
5: V4L2_CID_GAIN_OFFSET
6: V4L2_CID_BLUE_OFFSET
7: V4L2_CID_RED_OFFSET
8: V4L2_CID_GREEN_OFFSET
Hi Prabhakar,
As these are low level controls, I wonder whether it would make sense to
make a difference between digital and analogue gain. I admit I'm not quite
as certain whether there's such a large difference as there is for global
gains for the camera control algorithms.
Sorry to make this more complicated, but the Aptina MT9P031, for
instance (datasheet at
http://www.aptina.com/assets/downloadDocument.do?id=865 - see page 35),
has Digital Gain, an Analog Multiplier, and Analog Gain (for each of R,
Gr, Gb, and B). For each color channel, there is one register, with the
bits divided up into the three gain types. Furthermore, the different
gain types have different units (increments).
Currently (at least in the last version I've used), the driver hides all
this and provides a single gain control, and prioritizes which gain
types are adjusted at different user-level gain settings in accordance
with the datasheet recommendations (e.g. keep the analog gain between 1
and 4 for best noise performance, and use the multiplier for gains
between 4 and 8). This seems very sensible. If we try to distinguish
between analog and digital gains in the control definitions, what should
this driver do? And what about the multiplier? I suppose it could be
"hidden" by the driver as part of the analog gain, as the driver
currently does for the entire gain...
Cheers,
Chris
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