Re: OMAP3 ISP previewer Y10 to UYVY conversion

Sakari Ailus
2015-03-25T23:58:54Z

Hi Chris,

On Wed, Mar 25, 2015 at 09:12:56AM -0500, Chris Whittenburg wrote:
> Hi Sakari,
>
> Thanks for the reply.
>
> On Tue, Mar 24, 2015 at 6:51 PM, Sakari Ailus <sakari.ailus@iki.fi> wrote:
> > Do you know if the sensor has black level correction enabled? It appears to
> > have one, but I'm not completely sure what it does there. I'd check that it
> > is indeed enabled.
>
> The ar0130cs does have black level correction enabled by default.
>
> My thought is that since the 12-bit data from the CCDC looked ok, that
> it was something outside the sensor itself.

I think I might have misunderstood your original mail. I thought the images
from CCDC were bad.

> >> I've captured the 12-bit data from the CCDC, downconverted it to Y8,
> >> and verified it looks ok, and is not washed out, so I'm suspecting the
> >> isp previewer is doing something wrong in the simple Y10 to UYVY
> >> conversion.
> >
> > Not necessarily wrong, the black level correction might be enabled by
> > default, with the default configuration which works for most sensors (64 for
> > 10-bit data, 16 for 8-bit etc.).
>
> Ok, I will check this. You are referring to the "Camera ISP VPBE
> Preview Black Adjustment" which is controlled by PRV_BLKADJOFF
> register?

I guess it wasn't. The value appears to be zero by default, which makes
sense.

> I also found that there are contrast and brightness settings in the
> previewer which can be adjusted. I'm not changing them from defaults,
> so I thought the "Y" values would just get truncated to 8 bits and
> mapped into the UYVY without being significantly altered.
>
> Would your thought be the black level is more likely the issue rather
> than brightness/contrast?

I haven't used this part of the ISP, perhaps Laurent has.

--
Regards,

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