[v2,04/16] libipa: exposure_mode_helper: Take exposure/gain quantization into account
diff mbox series

Message ID 20250808141315.413839-5-stefan.klug@ideasonboard.com
State New
Headers show
Series
  • Implement WDR algorithm
Related show

Commit Message

Stefan Klug Aug. 8, 2025, 2:12 p.m. UTC 
In ExposureModeHelper::splitExposure() the quantization of exposure time
and gain is not taken into account. This can lead to visible flicker
when the quantization steps are too big. As a preparation to fixing
that, add a function to set the sensor line length and the current
sensor mode helper and extend the clampXXX functions to return the
quantization error.

By default the exposure time quantization is assumed to be 1us and gain
is assumed to not be quantized at all.

This patch doesn't introduce any functional changes.

Signed-off-by: Stefan Klug <stefan.klug@ideasonboard.com>
---
 src/ipa/libipa/exposure_mode_helper.cpp | 49 ++++++++++++++++++++-----
 src/ipa/libipa/exposure_mode_helper.h   | 10 ++++-
 2 files changed, 48 insertions(+), 11 deletions(-)

Comments

Kieran Bingham Aug. 11, 2025, 2:33 p.m. UTC | #1 
Quoting Stefan Klug (2025-08-08 15:12:42)
> In ExposureModeHelper::splitExposure() the quantization of exposure time
> and gain is not taken into account. This can lead to visible flicker
> when the quantization steps are too big. As a preparation to fixing
> that, add a function to set the sensor line length and the current
> sensor mode helper and extend the clampXXX functions to return the
> quantization error.
> 
> By default the exposure time quantization is assumed to be 1us and gain
> is assumed to not be quantized at all.
> 
> This patch doesn't introduce any functional changes.
> 
> Signed-off-by: Stefan Klug <stefan.klug@ideasonboard.com>
> ---
>  src/ipa/libipa/exposure_mode_helper.cpp | 49 ++++++++++++++++++++-----
>  src/ipa/libipa/exposure_mode_helper.h   | 10 ++++-
>  2 files changed, 48 insertions(+), 11 deletions(-)
> 
> diff --git a/src/ipa/libipa/exposure_mode_helper.cpp b/src/ipa/libipa/exposure_mode_helper.cpp
> index 0c1e99e31a47..d0a61908c966 100644
> --- a/src/ipa/libipa/exposure_mode_helper.cpp
> +++ b/src/ipa/libipa/exposure_mode_helper.cpp
> @@ -70,18 +70,37 @@ namespace ipa {
>   * the runtime limits set through setLimits() instead.
>   */
>  ExposureModeHelper::ExposureModeHelper(const Span<std::pair<utils::Duration, double>> stages)
> +       : lineLength_(1us), minExposureTime_(0us), maxExposureTime_(0us),
> +         minGain_(0), maxGain_(0), sensorHelper_(nullptr)
>  {
> -       minExposureTime_ = 0us;
> -       maxExposureTime_ = 0us;
> -       minGain_ = 0;
> -       maxGain_ = 0;
> -
>         for (const auto &[s, g] : stages) {
>                 exposureTimes_.push_back(s);
>                 gains_.push_back(g);
>         }
>  }
>  
> +/**
> + * \brief Configure sensor details
> + * \param[in] lineLength The current line length of the sensor
> + * \param[in] sensorHelper The sensor helper
> + *
> + * This function sets the line length and sensor helper. These are used in
> + * splitExposure() to take the quantization of the exposure and gain into
> + * account.
> + *
> + * When this is not called, is is assumed that exposure is in micro second
> + * granularity and gain has no quantization at all.
> + *
> + * The caller has to ensure that sensorHelper is valid for the lifetime of
> + * ExposureModeHelper or the next call to configure.
> + */
> +void ExposureModeHelper::configure(utils::Duration lineLength,
> +                                  const CameraSensorHelper *sensorHelper)
> +{
> +       lineLength_ = lineLength;
> +       sensorHelper_ = sensorHelper;
> +}
> +
>  /**
>   * \brief Set the exposure time and gain limits
>   * \param[in] minExposureTime The minimum exposure time supported
> @@ -108,14 +127,26 @@ void ExposureModeHelper::setLimits(utils::Duration minExposureTime,
>         maxGain_ = maxGain;
>  }
>  
> -utils::Duration ExposureModeHelper::clampExposureTime(utils::Duration exposureTime) const
> +utils::Duration ExposureModeHelper::clampExposureTime(utils::Duration exposureTime,
> +                                                     double *quantizationGain) const
>  {
> -       return std::clamp(exposureTime, minExposureTime_, maxExposureTime_);
> +       utils::Duration clamped;
> +       utils::Duration exp;
> +
> +       clamped = std::clamp(exposureTime, minExposureTime_, maxExposureTime_);
> +       exp = static_cast<long>(clamped / lineLength_) * lineLength_;
> +       if (quantizationGain)
> +               *quantizationGain = clamped / exp;
> +
> +       return exp;
>  }
>  
> -double ExposureModeHelper::clampGain(double gain) const
> +double ExposureModeHelper::clampGain(double gain, double *quantizationGain) const
>  {
> -       return std::clamp(gain, minGain_, maxGain_);
> +       double clamped = std::clamp(gain, minGain_, maxGain_);
> +       if (!sensorHelper_)
> +               return clamped;
> +       return sensorHelper_->quantizeGain(clamped, quantizationGain);
>  }
>  
>  /**
> diff --git a/src/ipa/libipa/exposure_mode_helper.h b/src/ipa/libipa/exposure_mode_helper.h
> index c5be1b6703a8..8701fae9a26e 100644
> --- a/src/ipa/libipa/exposure_mode_helper.h
> +++ b/src/ipa/libipa/exposure_mode_helper.h
> @@ -14,6 +14,8 @@
>  #include <libcamera/base/span.h>
>  #include <libcamera/base/utils.h>
>  
> +#include "camera_sensor_helper.h"
> +
>  namespace libcamera {
>  
>  namespace ipa {
> @@ -24,6 +26,7 @@ public:
>         ExposureModeHelper(const Span<std::pair<utils::Duration, double>> stages);
>         ~ExposureModeHelper() = default;
>  
> +       void configure(utils::Duration lineLength, const CameraSensorHelper *sensorHelper);
>         void setLimits(utils::Duration minExposureTime, utils::Duration maxExposureTime,
>                        double minGain, double maxGain);
>  
> @@ -36,16 +39,19 @@ public:
>         double maxGain() const { return maxGain_; }
>  
>  private:
> -       utils::Duration clampExposureTime(utils::Duration exposureTime) const;
> -       double clampGain(double gain) const;
> +       utils::Duration clampExposureTime(utils::Duration exposureTime,
> +                                         double *quantizationGain = nullptr) const;
> +       double clampGain(double gain, double *quantizationGain = nullptr) const;
>  
>         std::vector<utils::Duration> exposureTimes_;
>         std::vector<double> gains_;
>  
> +       utils::Duration lineLength_;
>         utils::Duration minExposureTime_;
>         utils::Duration maxExposureTime_;
>         double minGain_;
>         double maxGain_;


It seems like we're storing this sensor configuration information in
multiple places. I've seen it recently also stored in the rkisp1 agc
context data, which makes me wonder if there's something better to do
around this topic.

But for now - This patch say's there's no functional change and it helps
development so I'm fine with it.


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


> +       const CameraSensorHelper *sensorHelper_;

>  };
>  
>  } /* namespace ipa */
> -- 
> 2.48.1
>
Dan Scally Aug. 11, 2025, 2:36 p.m. UTC | #2 
Hi Stefan

On 08/08/2025 15:12, Stefan Klug wrote:
> In ExposureModeHelper::splitExposure() the quantization of exposure time
> and gain is not taken into account. This can lead to visible flicker
> when the quantization steps are too big. As a preparation to fixing
> that, add a function to set the sensor line length and the current
> sensor mode helper and extend the clampXXX functions to return the
> quantization error.
> 
> By default the exposure time quantization is assumed to be 1usand gain
> is assumed to not be quantized at all.
> 
> This patch doesn't introduce any functional changes.
> 
> Signed-off-by: Stefan Klug <stefan.klug@ideasonboard.com>

Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>

> ---
>   src/ipa/libipa/exposure_mode_helper.cpp | 49 ++++++++++++++++++++-----
>   src/ipa/libipa/exposure_mode_helper.h   | 10 ++++-
>   2 files changed, 48 insertions(+), 11 deletions(-)
> 
> diff --git a/src/ipa/libipa/exposure_mode_helper.cpp b/src/ipa/libipa/exposure_mode_helper.cpp
> index 0c1e99e31a47..d0a61908c966 100644
> --- a/src/ipa/libipa/exposure_mode_helper.cpp
> +++ b/src/ipa/libipa/exposure_mode_helper.cpp
> @@ -70,18 +70,37 @@ namespace ipa {
>    * the runtime limits set through setLimits() instead.
>    */
>   ExposureModeHelper::ExposureModeHelper(const Span<std::pair<utils::Duration, double>> stages)
> +	: lineLength_(1us), minExposureTime_(0us), maxExposureTime_(0us),
> +	  minGain_(0), maxGain_(0), sensorHelper_(nullptr)
>   {
> -	minExposureTime_ = 0us;
> -	maxExposureTime_ = 0us;
> -	minGain_ = 0;
> -	maxGain_ = 0;
> -
>   	for (const auto &[s, g] : stages) {
>   		exposureTimes_.push_back(s);
>   		gains_.push_back(g);
>   	}
>   }
>   
> +/**
> + * \brief Configure sensor details
> + * \param[in] lineLength The current line length of the sensor
> + * \param[in] sensorHelper The sensor helper
> + *
> + * This function sets the line length and sensor helper. These are used in
> + * splitExposure() to take the quantization of the exposure and gain into
> + * account.
> + *
> + * When this is not called, is is assumed that exposure is in micro second
> + * granularity and gain has no quantization at all.
> + *
> + * The caller has to ensure that sensorHelper is valid for the lifetime of
> + * ExposureModeHelper or the next call to configure.
> + */
> +void ExposureModeHelper::configure(utils::Duration lineLength,
> +				   const CameraSensorHelper *sensorHelper)
> +{
> +	lineLength_ = lineLength;
> +	sensorHelper_ = sensorHelper;
> +}
> +
>   /**
>    * \brief Set the exposure time and gain limits
>    * \param[in] minExposureTime The minimum exposure time supported
> @@ -108,14 +127,26 @@ void ExposureModeHelper::setLimits(utils::Duration minExposureTime,
>   	maxGain_ = maxGain;
>   }
>   
> -utils::Duration ExposureModeHelper::clampExposureTime(utils::Duration exposureTime) const
> +utils::Duration ExposureModeHelper::clampExposureTime(utils::Duration exposureTime,
> +						      double *quantizationGain) const
>   {
> -	return std::clamp(exposureTime, minExposureTime_, maxExposureTime_);
> +	utils::Duration clamped;
> +	utils::Duration exp;
> +
> +	clamped = std::clamp(exposureTime, minExposureTime_, maxExposureTime_);
> +	exp = static_cast<long>(clamped / lineLength_) * lineLength_;
> +	if (quantizationGain)
> +		*quantizationGain = clamped / exp;
> +
> +	return exp;
>   }
>   
> -double ExposureModeHelper::clampGain(double gain) const
> +double ExposureModeHelper::clampGain(double gain, double *quantizationGain) const
>   {
> -	return std::clamp(gain, minGain_, maxGain_);
> +	double clamped = std::clamp(gain, minGain_, maxGain_);
> +	if (!sensorHelper_)
> +		return clamped;
> +	return sensorHelper_->quantizeGain(clamped, quantizationGain);
>   }
>   
>   /**
> diff --git a/src/ipa/libipa/exposure_mode_helper.h b/src/ipa/libipa/exposure_mode_helper.h
> index c5be1b6703a8..8701fae9a26e 100644
> --- a/src/ipa/libipa/exposure_mode_helper.h
> +++ b/src/ipa/libipa/exposure_mode_helper.h
> @@ -14,6 +14,8 @@
>   #include <libcamera/base/span.h>
>   #include <libcamera/base/utils.h>
>   
> +#include "camera_sensor_helper.h"
> +
>   namespace libcamera {
>   
>   namespace ipa {
> @@ -24,6 +26,7 @@ public:
>   	ExposureModeHelper(const Span<std::pair<utils::Duration, double>> stages);
>   	~ExposureModeHelper() = default;
>   
> +	void configure(utils::Duration lineLength, const CameraSensorHelper *sensorHelper);
>   	void setLimits(utils::Duration minExposureTime, utils::Duration maxExposureTime,
>   		       double minGain, double maxGain);
>   
> @@ -36,16 +39,19 @@ public:
>   	double maxGain() const { return maxGain_; }
>   
>   private:
> -	utils::Duration clampExposureTime(utils::Duration exposureTime) const;
> -	double clampGain(double gain) const;
> +	utils::Duration clampExposureTime(utils::Duration exposureTime,
> +					  double *quantizationGain = nullptr) const;
> +	double clampGain(double gain, double *quantizationGain = nullptr) const;
>   
>   	std::vector<utils::Duration> exposureTimes_;
>   	std::vector<double> gains_;
>   
> +	utils::Duration lineLength_;
>   	utils::Duration minExposureTime_;
>   	utils::Duration maxExposureTime_;
>   	double minGain_;
>   	double maxGain_;
> +	const CameraSensorHelper *sensorHelper_;
>   };
>   
>   } /* namespace ipa */

Patch
diff mbox series 

diff --git a/src/ipa/libipa/exposure_mode_helper.cpp b/src/ipa/libipa/exposure_mode_helper.cpp
index 0c1e99e31a47..d0a61908c966 100644
--- a/src/ipa/libipa/exposure_mode_helper.cpp
+++ b/src/ipa/libipa/exposure_mode_helper.cpp
@@ -70,18 +70,37 @@  namespace ipa {
  * the runtime limits set through setLimits() instead.
  */
 ExposureModeHelper::ExposureModeHelper(const Span<std::pair<utils::Duration, double>> stages)
+	: lineLength_(1us), minExposureTime_(0us), maxExposureTime_(0us),
+	  minGain_(0), maxGain_(0), sensorHelper_(nullptr)
 {
-	minExposureTime_ = 0us;
-	maxExposureTime_ = 0us;
-	minGain_ = 0;
-	maxGain_ = 0;
-
 	for (const auto &[s, g] : stages) {
 		exposureTimes_.push_back(s);
 		gains_.push_back(g);
 	}
 }
 
+/**
+ * \brief Configure sensor details
+ * \param[in] lineLength The current line length of the sensor
+ * \param[in] sensorHelper The sensor helper
+ *
+ * This function sets the line length and sensor helper. These are used in
+ * splitExposure() to take the quantization of the exposure and gain into
+ * account.
+ *
+ * When this is not called, is is assumed that exposure is in micro second
+ * granularity and gain has no quantization at all.
+ *
+ * The caller has to ensure that sensorHelper is valid for the lifetime of
+ * ExposureModeHelper or the next call to configure.
+ */
+void ExposureModeHelper::configure(utils::Duration lineLength,
+				   const CameraSensorHelper *sensorHelper)
+{
+	lineLength_ = lineLength;
+	sensorHelper_ = sensorHelper;
+}
+
 /**
  * \brief Set the exposure time and gain limits
  * \param[in] minExposureTime The minimum exposure time supported
@@ -108,14 +127,26 @@  void ExposureModeHelper::setLimits(utils::Duration minExposureTime,
 	maxGain_ = maxGain;
 }
 
-utils::Duration ExposureModeHelper::clampExposureTime(utils::Duration exposureTime) const
+utils::Duration ExposureModeHelper::clampExposureTime(utils::Duration exposureTime,
+						      double *quantizationGain) const
 {
-	return std::clamp(exposureTime, minExposureTime_, maxExposureTime_);
+	utils::Duration clamped;
+	utils::Duration exp;
+
+	clamped = std::clamp(exposureTime, minExposureTime_, maxExposureTime_);
+	exp = static_cast<long>(clamped / lineLength_) * lineLength_;
+	if (quantizationGain)
+		*quantizationGain = clamped / exp;
+
+	return exp;
 }
 
-double ExposureModeHelper::clampGain(double gain) const
+double ExposureModeHelper::clampGain(double gain, double *quantizationGain) const
 {
-	return std::clamp(gain, minGain_, maxGain_);
+	double clamped = std::clamp(gain, minGain_, maxGain_);
+	if (!sensorHelper_)
+		return clamped;
+	return sensorHelper_->quantizeGain(clamped, quantizationGain);
 }
 
 /**
diff --git a/src/ipa/libipa/exposure_mode_helper.h b/src/ipa/libipa/exposure_mode_helper.h
index c5be1b6703a8..8701fae9a26e 100644
--- a/src/ipa/libipa/exposure_mode_helper.h
+++ b/src/ipa/libipa/exposure_mode_helper.h
@@ -14,6 +14,8 @@ 
 #include <libcamera/base/span.h>
 #include <libcamera/base/utils.h>
 
+#include "camera_sensor_helper.h"
+
 namespace libcamera {
 
 namespace ipa {
@@ -24,6 +26,7 @@  public:
 	ExposureModeHelper(const Span<std::pair<utils::Duration, double>> stages);
 	~ExposureModeHelper() = default;
 
+	void configure(utils::Duration lineLength, const CameraSensorHelper *sensorHelper);
 	void setLimits(utils::Duration minExposureTime, utils::Duration maxExposureTime,
 		       double minGain, double maxGain);
 
@@ -36,16 +39,19 @@  public:
 	double maxGain() const { return maxGain_; }
 
 private:
-	utils::Duration clampExposureTime(utils::Duration exposureTime) const;
-	double clampGain(double gain) const;
+	utils::Duration clampExposureTime(utils::Duration exposureTime,
+					  double *quantizationGain = nullptr) const;
+	double clampGain(double gain, double *quantizationGain = nullptr) const;
 
 	std::vector<utils::Duration> exposureTimes_;
 	std::vector<double> gains_;
 
+	utils::Duration lineLength_;
 	utils::Duration minExposureTime_;
 	utils::Duration maxExposureTime_;
 	double minGain_;
 	double maxGain_;
+	const CameraSensorHelper *sensorHelper_;
 };
 
 } /* namespace ipa */