[PATCH] ipa: rpi: awb: Disable CT search bias for Grey World AWB

[David Plowman]

Hi Naush

Thanks for the patch. Yes, we should probably have spotted this
earlier. But I'll add a test for grey world AWB so that we don't get
caught out like this again!

On Tue, 19 Nov 2024 at 08:55, Naushir Patuck <naush at raspberrypi.com> wrote:
>
> If grey world AWB is setup in the tuning file, the CT curve will either
> be missing or invalid. Disable biasing the statistics for the search in
> such cases.
>
> Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
> ---
>  src/ipa/rpi/controller/rpi/awb.cpp | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/src/ipa/rpi/controller/rpi/awb.cpp b/src/ipa/rpi/controller/rpi/awb.cpp
> index 9d8e170d1bfe..87b1b077ffb8 100644
> --- a/src/ipa/rpi/controller/rpi/awb.cpp
> +++ b/src/ipa/rpi/controller/rpi/awb.cpp
> @@ -459,10 +459,13 @@ void Awb::prepareStats()
>          * LSC has already been applied to the stats in this pipeline, so stop
>          * any LSC compensation.  We also ignore config_.fast in this version.
>          */
> +       const double biasCtR = config_.bayes && config_.ctR.size() ?
> +                              config_.ctR.eval(config_.biasCT) : 0;
> +       const double biasCtB = config_.bayes && config_.ctB.size() ?
> +                              config_.ctB.eval(config_.biasCT) : 0;

I'm OK with this, though perhaps "empty()" is microscopically better
than "size()" here? Actually, I think the read function ensures that
the PWLs are set if bayes is, so we could leave it out completely. But
either way I'm not overly bothered:

Reviewed-by: David Plowman <david.plowman at raspberrypi.com>

David

>         generateStats(zones_, statistics_, config_.minPixels,
>                       config_.minG, getGlobalMetadata(),
> -                     config_.biasProportion, config_.ctR.eval(config_.biasCT),
> -                     config_.ctB.eval(config_.biasCT));
> +                     config_.biasProportion, biasCtR, biasCtB);
>         /*
>          * apply sensitivities, so values appear to come from our "canonical"
>          * sensor.
> --
> 2.34.1
>