[libcamera-devel] [PATCH] ipa: rpi: awb: Make is possible to set the colour temperature directly

[Laurent Pinchart]

Hi David,

Thank you for the patch.

On Fri, Nov 10, 2023 at 04:14:33PM +0000, David Plowman via libcamera-devel wrote:
> ColourTemperature is now exported as a writable control so that
> algorithms can set it directly.

I'm puzzled here. You mention algorithms, but the patch exposes the
control as being writable from applications. Is it a typo in the commit
message ? If so, what's the use case ? control_ids.yaml documents the
control as

  - ColourTemperature:
      type: int32_t
      description: Report the current estimate of the colour temperature, in
        kelvin, for this frame. The ColourTemperature control can only be
        returned in metadata.

so this would need to be updated as a prerequisite for this patch.

> The AWB algorithm class now requires a
> method to be provided to perform this operation. The method should
> clamp the passed value to the calibrated range known to the algorithm.
> 
> The default range is set very wide to cover all conceivable future AWB
> calibrations. It will always be clamped before use.
> 
> Signed-off-by: David Plowman <david.plowman at raspberrypi.com>
> ---
>  src/ipa/rpi/common/ipa_base.cpp        | 20 ++++++++++++++++++++
>  src/ipa/rpi/controller/awb_algorithm.h |  1 +
>  src/ipa/rpi/controller/rpi/awb.cpp     | 18 ++++++++++++++++++
>  src/ipa/rpi/controller/rpi/awb.h       |  1 +
>  4 files changed, 40 insertions(+)
> 
> diff --git a/src/ipa/rpi/common/ipa_base.cpp b/src/ipa/rpi/common/ipa_base.cpp
> index 97a32522..cd1d6e3d 100644
> --- a/src/ipa/rpi/common/ipa_base.cpp
> +++ b/src/ipa/rpi/common/ipa_base.cpp
> @@ -80,6 +80,7 @@ const ControlInfoMap::Map ipaColourControls{
>  	{ &controls::AwbEnable, ControlInfo(false, true) },
>  	{ &controls::AwbMode, ControlInfo(controls::AwbModeValues) },
>  	{ &controls::ColourGains, ControlInfo(0.0f, 32.0f) },
> +	{ &controls::ColourTemperature, ControlInfo(100, 100000) },
>  	{ &controls::Saturation, ControlInfo(0.0f, 32.0f, 1.0f) },
>  };
>  
> @@ -972,6 +973,25 @@ void IpaBase::applyControls(const ControlList &controls)
>  			break;
>  		}
>  
> +		case controls::COLOUR_TEMPERATURE: {
> +			/* Silently ignore this control for a mono sensor. */
> +			if (monoSensor_)
> +				break;
> +
> +			auto temperatureK = ctrl.second.get<int32_t>();
> +			RPiController::AwbAlgorithm *awb = dynamic_cast<RPiController::AwbAlgorithm *>(
> +				controller_.getAlgorithm("awb"));
> +			if (!awb) {
> +				LOG(IPARPI, Warning)
> +					<< "Could not set COLOUR_TEMPERATURE - no AWB algorithm";
> +				break;
> +			}
> +
> +			awb->setColourTemperature(temperatureK);
> +			/* This metadata will get reported back automatically. */
> +			break;
> +		}
> +
>  		case controls::BRIGHTNESS: {
>  			RPiController::ContrastAlgorithm *contrast = dynamic_cast<RPiController::ContrastAlgorithm *>(
>  				controller_.getAlgorithm("contrast"));
> diff --git a/src/ipa/rpi/controller/awb_algorithm.h b/src/ipa/rpi/controller/awb_algorithm.h
> index 8462c4db..d966dfa8 100644
> --- a/src/ipa/rpi/controller/awb_algorithm.h
> +++ b/src/ipa/rpi/controller/awb_algorithm.h
> @@ -18,6 +18,7 @@ public:
>  	virtual unsigned int getConvergenceFrames() const = 0;
>  	virtual void setMode(std::string const &modeName) = 0;
>  	virtual void setManualGains(double manualR, double manualB) = 0;
> +	virtual void setColourTemperature(double temperatureK) = 0;
>  	virtual void enableAuto() = 0;
>  	virtual void disableAuto() = 0;
>  };
> diff --git a/src/ipa/rpi/controller/rpi/awb.cpp b/src/ipa/rpi/controller/rpi/awb.cpp
> index 5ae0c2fa..0918e20d 100644
> --- a/src/ipa/rpi/controller/rpi/awb.cpp
> +++ b/src/ipa/rpi/controller/rpi/awb.cpp
> @@ -275,6 +275,24 @@ void Awb::setManualGains(double manualR, double manualB)
>  	}
>  }
>  
> +void Awb::setColourTemperature(double temperatureK)
> +{
> +	if (!config_.bayes) {
> +		LOG(RPiAwb, Warning) << "AWB uncalibrated - cannot set colour temperature";
> +		return;
> +	}
> +
> +	temperatureK = config_.ctR.domain().clip(temperatureK);
> +	manualR_ = 1 / config_.ctR.eval(temperatureK);
> +	manualB_ = 1 / config_.ctB.eval(temperatureK);
> +
> +	syncResults_.temperatureK = temperatureK;
> +	syncResults_.gainR = manualR_;
> +	syncResults_.gainG = 1.0;
> +	syncResults_.gainB = manualB_;
> +	prevSyncResults_ = syncResults_;
> +}
> +
>  void Awb::switchMode([[maybe_unused]] CameraMode const &cameraMode,
>  		     Metadata *metadata)
>  {
> diff --git a/src/ipa/rpi/controller/rpi/awb.h b/src/ipa/rpi/controller/rpi/awb.h
> index e7d49cd8..dbd79eda 100644
> --- a/src/ipa/rpi/controller/rpi/awb.h
> +++ b/src/ipa/rpi/controller/rpi/awb.h
> @@ -97,6 +97,7 @@ public:
>  	unsigned int getConvergenceFrames() const override;
>  	void setMode(std::string const &name) override;
>  	void setManualGains(double manualR, double manualB) override;
> +	void setColourTemperature(double temperatureK) override;
>  	void enableAuto() override;
>  	void disableAuto() override;
>  	void switchMode(CameraMode const &cameraMode, Metadata *metadata) override;

-- 
Regards,

Laurent Pinchart