[libcamera-devel,v5,32/33] ipa: rkisp1: awb: Freeze AWB when means are too small

17443 diff mbox series

When the RGB means are too small, gains and color temperature can't be
meaningfully calculated. Freeze the AWB in that case, using the
previously calculated values.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
---
 src/ipa/rkisp1/algorithms/awb.cpp | 17 ++++++++++++++++-
 src/ipa/rkisp1/ipa_context.cpp    |  3 +++
 src/ipa/rkisp1/ipa_context.h      |  1 +
 3 files changed, 20 insertions(+), 1 deletion(-)

Hi Laurent

On Tue, Sep 27, 2022 at 05:36:41AM +0300, Laurent Pinchart via libcamera-devel wrote:
> When the RGB means are too small, gains and color temperature can't be
> meaningfully calculated. Freeze the AWB in that case, using the
> previously calculated values.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>

Thanks
   j

> ---
>  src/ipa/rkisp1/algorithms/awb.cpp | 17 ++++++++++++++++-
>  src/ipa/rkisp1/ipa_context.cpp    |  3 +++
>  src/ipa/rkisp1/ipa_context.h      |  1 +
>  3 files changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/src/ipa/rkisp1/algorithms/awb.cpp b/src/ipa/rkisp1/algorithms/awb.cpp
> index a3066fbb1994..eb32cd722071 100644
> --- a/src/ipa/rkisp1/algorithms/awb.cpp
> +++ b/src/ipa/rkisp1/algorithms/awb.cpp
> @@ -31,6 +31,9 @@ namespace ipa::rkisp1::algorithms {
>
>  LOG_DEFINE_CATEGORY(RkISP1Awb)
>
> +/* Minimum mean value below which AWB can't operate. */
> +constexpr double kMeanMinThreshold = 2.0;
> +
>  Awb::Awb()
>  	: rgbMode_(false)
>  {
> @@ -263,7 +266,17 @@ void Awb::process(IPAContext &context,
>  	greenMean /= frameContext.awb.gains.green;
>  	blueMean /= frameContext.awb.gains.blue;
>
> -	frameContext.awb.temperatureK = estimateCCT(redMean, greenMean, blueMean);
> +	/*
> +	 * If the means are too small we don't have enough information to
> +	 * meaningfully calculate gains. Freeze the algorithm in that case.
> +	 */
> +	if (redMean < kMeanMinThreshold && greenMean < kMeanMinThreshold &&
> +	    blueMean < kMeanMinThreshold) {
> +		frameContext.awb.temperatureK = activeState.awb.temperatureK;
> +		return;
> +	}
> +
> +	activeState.awb.temperatureK = estimateCCT(redMean, greenMean, blueMean);
>
>  	/*
>  	 * Estimate the red and blue gains to apply in a grey world. The green
> @@ -290,6 +303,8 @@ void Awb::process(IPAContext &context,
>  	activeState.awb.gains.automatic.blue = blueGain;
>  	activeState.awb.gains.automatic.green = 1.0;
>
> +	frameContext.awb.temperatureK = activeState.awb.temperatureK;
> +
>  	LOG(RkISP1Awb, Debug) << std::showpoint
>  		<< "Means [" << redMean << ", " << greenMean << ", " << blueMean
>  		<< "], gains [" << activeState.awb.gains.automatic.red << ", "
> diff --git a/src/ipa/rkisp1/ipa_context.cpp b/src/ipa/rkisp1/ipa_context.cpp
> index 2126ed1d0acb..b00dc29c1713 100644
> --- a/src/ipa/rkisp1/ipa_context.cpp
> +++ b/src/ipa/rkisp1/ipa_context.cpp
> @@ -156,6 +156,9 @@ namespace libcamera::ipa::rkisp1 {
>   * \var IPAActiveState::awb.gains.automatic.blue
>   * \brief Automatic white balance gain for B channel
>   *
> + * \var IPAActiveState::awb.temperatureK
> + * \brief Estimated color temperature
> + *
>   * \var IPAActiveState::awb.autoEnabled
>   * \brief Whether the Auto White Balance algorithm is enabled
>   */
> diff --git a/src/ipa/rkisp1/ipa_context.h b/src/ipa/rkisp1/ipa_context.h
> index d0692f872960..0677c8c35d73 100644
> --- a/src/ipa/rkisp1/ipa_context.h
> +++ b/src/ipa/rkisp1/ipa_context.h
> @@ -69,6 +69,7 @@ struct IPAActiveState {
>  			} automatic;
>  		} gains;
>
> +		unsigned int temperatureK;
>  		bool autoEnabled;
>  	} awb;
>
> --
> Regards,
>
> Laurent Pinchart
>