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	queueRequest (IPAContext &context, const uint32_t frame, IPAFrameContext &frameContext, const ControlList &controls) override
	Provide control values to the algorithm.
void	prepare (IPAContext &context, const uint32_t frame, IPAFrameContext &frameContext, ipu3_uapi_params *params) override
	Fill the params buffer with ISP processing parameters for a frame.
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.

Additional Inherited Members
Public Types inherited from libcamera::ipa::Algorithm< _Module >
using	Module = _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

prepare()

void libcamera::ipa::ipu3::algorithms::Agc::prepare ( IPAContext &  context, const uint32_t  frame, IPAFrameContext &  frameContext, ipu3_uapi_params *  params  )

override

Fill the params buffer with ISP processing parameters for a frame.

Parameters

[in]	context	The shared IPA context
[in]	frame	The frame context sequence number
[in]	frameContext	The FrameContext for this frame
[out]	params	The ISP specific parameters

This function is called for every frame when the camera is running before it is processed by the ISP to prepare the ISP processing parameters for that frame.

Algorithms shall fill in the parameter structure fields appropriately to configure the ISP processing blocks that they are responsible for. This includes setting fields and flags that enable those processing blocks.

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.

queueRequest()

void libcamera::ipa::ipu3::algorithms::Agc::queueRequest ( IPAContext &  context, const uint32_t  frame, IPAFrameContext &  frameContext, const ControlList &  controls  )

override

Provide control values to the algorithm.

Parameters

[in]	context	The shared IPA context
[in]	frame	The frame number to apply the control values
[in]	frameContext	The current frame's context
[in]	controls	The list of user controls

This function is called for each request queued to the camera. It provides the controls stored in the request to the algorithm. The frame number is the Request sequence number and identifies the desired corresponding frame to target for the controls to take effect.

Algorithms shall read the applicable controls and store their value for later use during frame processing.

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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