[PATCH 07/10] ipa: rkisp1: Damp color temperature regulation

[Kieran Bingham]

Quoting Stefan Klug (2025-02-17 10:01:48)
> Damp the regulation of the color temperature with the same factor as the
> gains.  Not damping the color temperature leads to visible flicker, as
> the CCM changes too much.

Interesting, I thought we had something on the CCM interplotator so it
wouldn't change too much on small movements of the colour temperature,
but I guess smoothing out the colour temperature is reasonable anyway -
especially as it's an estimate. I wonder if we should have some sort of
IIR instances to make these a bit more specific, but the speed is fine
now.


Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>


Or maybe we should report the real calculated value to metadata, but
filter it on the input to the CCM interpolator ?

> 
> Signed-off-by: Stefan Klug <stefan.klug at ideasonboard.com>
> ---
>  src/ipa/rkisp1/algorithms/awb.cpp | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/src/ipa/rkisp1/algorithms/awb.cpp b/src/ipa/rkisp1/algorithms/awb.cpp
> index 9244a1e64f41..347d38d226b4 100644
> --- a/src/ipa/rkisp1/algorithms/awb.cpp
> +++ b/src/ipa/rkisp1/algorithms/awb.cpp
> @@ -320,8 +320,6 @@ void Awb::process(IPAContext &context,
>             rgbMeans.b() < kMeanMinThreshold)
>                 return;
>  
> -       activeState.awb.automatic.temperatureK = estimateCCT(rgbMeans);
> -
>         /*
>          * Estimate the red and blue gains to apply in a grey world. The green
>          * gain is hardcoded to 1.0. Avoid divisions by zero by clamping the
> @@ -343,8 +341,11 @@ void Awb::process(IPAContext &context,
>  
>         /* Filter the values to avoid oscillations. */
>         double speed = 0.2;
> +       double ct = estimateCCT(rgbMeans);
> +       ct = ct * speed + activeState.awb.automatic.temperatureK * (1 - speed);
>         gains = gains * speed + activeState.awb.automatic.gains * (1 - speed);
>  
> +       activeState.awb.automatic.temperatureK = static_cast<unsigned int>(ct);
>         activeState.awb.automatic.gains = gains;
>  
>         LOG(RkISP1Awb, Debug)
> -- 
> 2.43.0
>