[PATCH v3 14/16] ipa: rkisp1: Damp color temperature regulation

[Paul Elder]

On Thu, Apr 03, 2025 at 05:49:19PM +0200, Stefan Klug wrote:
> 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.
> 
> Signed-off-by: Stefan Klug <stefan.klug at ideasonboard.com>
> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>

Reviewed-by: Paul Elder <paul.elder at ideasonboard.com>

> 
> ---
> 
> Changes in v2:
> - Collected tags
> 
> Changes in v3:
> - Dropped incorrect call to estimateCCT()
> ---
>  src/ipa/rkisp1/algorithms/awb.cpp | 5 +++--
>  src/ipa/rkisp1/algorithms/ccm.cpp | 4 ----
>  2 files changed, 3 insertions(+), 6 deletions(-)
> 
> diff --git a/src/ipa/rkisp1/algorithms/awb.cpp b/src/ipa/rkisp1/algorithms/awb.cpp
> index f5415a0bb99d..47b29725af51 100644
> --- a/src/ipa/rkisp1/algorithms/awb.cpp
> +++ b/src/ipa/rkisp1/algorithms/awb.cpp
> @@ -317,8 +317,6 @@ void Awb::process(IPAContext &context,
>  	RkISP1AwbStats awbStats{ rgbMeans };
>  	AwbResult awbResult = awbAlgo_->calculateAwb(awbStats, frameContext.lux.lux);
>  
> -	activeState.awb.automatic.temperatureK = awbResult.colourTemperature;
> -
>  	/*
>  	 * Clamp the gain values to the hardware, which expresses gains as Q2.8
>  	 * unsigned integer values. Set the minimum just above zero to avoid
> @@ -329,9 +327,12 @@ void Awb::process(IPAContext &context,
>  
>  	/* Filter the values to avoid oscillations. */
>  	double speed = 0.2;
> +	double ct = awbResult.colourTemperature;
> +	ct = ct * speed + activeState.awb.automatic.temperatureK * (1 - speed);
>  	awbResult.gains = awbResult.gains * speed +
>  			  activeState.awb.automatic.gains * (1 - speed);
>  
> +	activeState.awb.automatic.temperatureK = static_cast<unsigned int>(ct);
>  	activeState.awb.automatic.gains = awbResult.gains;
>  
>  	LOG(RkISP1Awb, Debug)
> diff --git a/src/ipa/rkisp1/algorithms/ccm.cpp b/src/ipa/rkisp1/algorithms/ccm.cpp
> index 3a96a5427bc6..de2b6fe775aa 100644
> --- a/src/ipa/rkisp1/algorithms/ccm.cpp
> +++ b/src/ipa/rkisp1/algorithms/ccm.cpp
> @@ -142,10 +142,6 @@ void Ccm::prepare(IPAContext &context, const uint32_t frame,
>  	}
>  
>  	uint32_t ct = frameContext.awb.temperatureK;
> -	/*
> -	 * \todo The colour temperature will likely be noisy, add filtering to
> -	 * avoid updating the CCM matrix all the time.
> -	 */
>  	if (frame > 0 && ct == ct_) {
>  		frameContext.ccm.ccm = context.activeState.ccm.automatic;
>  		return;
> -- 
> 2.43.0
>