libcamera::ipa::ipu3::algorithms::Agc Class Reference

A mean-based auto-exposure algorithm. More...

Inheritance diagram for libcamera::ipa::ipu3::algorithms::Agc:

Collaboration diagram for libcamera::ipa::ipu3::algorithms::Agc:

Public Member Functions
int	init (IPAContext &context, const ValueNode &tuningData) override
	Initialise the AGC algorithm from tuning files.
int	configure (IPAContext &context, const IPAConfigInfo &configInfo) override
	Configure the AGC given a configInfo.
void	process (IPAContext &context, const uint32_t frame, IPAFrameContext &frameContext, const ipu3_uapi_stats_3a *stats, ControlList &metadata) override
	Process IPU3 statistics, and run AGC operations.
Public Member Functions inherited from libcamera::ipa::Algorithm< Module >
virtual int	init (typename Module::Context &context, const ValueNode &tuningData)
	Initialize the Algorithm with tuning data.
virtual int	configure (typename Module::Context &context, const typename Module::Config &configInfo)
	Configure the Algorithm given an IPAConfigInfo.
virtual void	queueRequest (typename Module::Context &context, const uint32_t frame, typename Module::FrameContext &frameContext, const ControlList &controls)
	Provide control values to the algorithm.
virtual void	prepare (typename Module::Context &context, const uint32_t frame, typename Module::FrameContext &frameContext, typename Module::Params *params)
	Fill the params buffer with ISP processing parameters for a frame.
virtual void	process (typename Module::Context &context, const uint32_t frame, typename Module::FrameContext &frameContext, const typename Module::Stats *stats, ControlList &metadata)
	Process ISP statistics, and run algorithm operations.
Public Member Functions inherited from libcamera::ipa::AgcMeanLuminance
void	configure (utils::Duration lineDuration, const CameraSensorHelper *sensorHelper)
	Configure the exposure mode helpers.
int	parseTuningData (const ValueNode &tuningData)
	Parse tuning data for AeConstraintMode and AeExposureMode controls.
void	setExposureCompensation (double gain)
	Set the exposure compensation value.
void	setLux (unsigned int lux)
	Set the lux level.
void	setLimits (utils::Duration minExposureTime, utils::Duration maxExposureTime, double minGain, double maxGain, std::vector< AgcConstraint > constraints)
	Set the ExposureModeHelper limits for this class.
const std::map< int32_t, std::vector< AgcConstraint > > &	constraintModes () const
	Get the constraint modes that have been parsed from tuning data.
const std::map< int32_t, std::shared_ptr< ExposureModeHelper > > &	exposureModeHelpers () const
	Get the ExposureModeHelpers that have been parsed from tuning data.
ControlInfoMap::Map	controls ()
	Get the controls that have been generated after parsing tuning data.
std::tuple< utils::Duration, double, double, double >	calculateNewEv (uint32_t constraintModeIndex, uint32_t exposureModeIndex, const Histogram &yHist, utils::Duration effectiveExposureValue)
	Calculate the new exposure value and splut it between exposure time and gain.
double	effectiveYTarget () const
	Get the currently effective y target.
void	resetFrameCount ()
	Reset the frame counter.

Additional Inherited Members
Public Types inherited from libcamera::ipa::Algorithm< Module >
using	Module
	The IPA module type for this class of algorithms.

Detailed Description

A mean-based auto-exposure algorithm.

This algorithm calculates an exposure time and an analogue gain so that the average value of the green channel of the brightest 2% of pixels approaches 0.5. The AWB gains are not used here, and all cells in the grid have the same weight, like an average-metering case. In this metering mode, the camera uses light information from the entire scene and creates an average for the final exposure setting, giving no weighting to any particular portion of the metered area.

Reference: Battiato, Messina & Castorina. (2008). Exposure Correction for Imaging Devices: An Overview. 10.1201/9781420054538.ch12.

Member Function Documentation

configure()

int libcamera::ipa::ipu3::algorithms::Agc::configure ( IPAContext & context, const IPAConfigInfo & configInfo )

override

Configure the AGC given a configInfo.

Parameters

[in]	context	The shared IPA context
[in]	configInfo	The IPA configuration data

Returns

0

init()

int libcamera::ipa::ipu3::algorithms::Agc::init ( IPAContext & context, const ValueNode & tuningData )

override

Initialise the AGC algorithm from tuning files.

Parameters

[in]	context	The shared IPA context
[in]	tuningData	The ValueNode containing Agc tuning data

This function calls the base class' tuningData parsers to discover which control values are supported.

Returns

0 on success or errors from the base class

process()

void libcamera::ipa::ipu3::algorithms::Agc::process ( IPAContext & context, const uint32_t frame, IPAFrameContext & frameContext, const ipu3_uapi_stats_3a * stats, ControlList & metadata )

override

Process IPU3 statistics, and run AGC operations.

Parameters

[in]	context	The shared IPA context
[in]	frame	The current frame sequence number
[in]	frameContext	The current frame context
[in]	stats	The IPU3 statistics and ISP results
[out]	metadata	Metadata for the frame, to be filled by the algorithm

Identify the current image brightness, and use that to estimate the optimal new exposure and gain for the scene.

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The documentation for this class was generated from the following files:

• src/ipa/ipu3/algorithms/agc.h
• src/ipa/ipu3/algorithms/agc.cpp