Base class for computing sensor tuning parameters using sensorspecific constants.
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Base class for computing sensor tuning parameters using sensorspecific constants.
Instances derived from CameraSensorHelper class are sensorspecific. Each supported sensor will have an associated base class defined.
◆ AnalogueGainType
The gain calculation modes as defined by the MIPI CCS.
Describes the image sensor analogue gain capabilities. Two modes are possible, depending on the sensor: Linear and Exponential.
Enumerator 

AnalogueGainLinear  Gain is computed using linear gain estimation.
The relationship between the integer gain parameter and the resulting gain multiplier is given by the following equation:
Where 'x' is the gain control parameter, and m0, m1, c0 and c1 are imagesensorspecific constants of the sensor. These constants are static parameters, and for any given image sensor either m0 or m1 shall be zero.
The full Gain equation therefore reduces to either:
or

AnalogueGainExponential  Gain is expressed using an exponential model.
The relationship between the integer gain parameter and the resulting gain multiplier is given by the following equation:
Where 'x' is the gain control parameter, and 'a' and 'm' are image sensorspecific constants.
This is a subset of the MIPI CCS exponential gain model with the linear factor 'a' being a constant, but with the exponent being configurable through the 'm' coefficient.
When the gain is expressed in dB, 'a' is equal to 1 and 'm' to .

◆ gain()
double libcamera::ipa::CameraSensorHelper::gain 
( 
uint32_t 
gainCode  ) 
const 

virtual 
Compute the real gain from the V4L2 subdev control gain code.
 Parameters

[in]  gainCode  The V4L2 subdev control gain 
This function aims to abstract the calculation of the gain letting the IPA use the real gain for its estimations. It is the counterpart of the function CameraSensorHelper::gainCode.
 Returns
 The real gain
◆ gainCode()
uint32_t libcamera::ipa::CameraSensorHelper::gainCode 
( 
double 
gain  ) 
const 

virtual 
Construct a CameraSensorHelper instance.
CameraSensorHelper derived class instances shall never be constructed manually but always through the CameraSensorHelperFactoryBase::create() function. Compute gain code from the analogue gain absolute value
 Parameters

[in]  gain  The real gain to pass 
This function aims to abstract the calculation of the gain letting the IPA use the real gain for its estimations.
 Returns
 The gain code to pass to V4L2
◆ gainConstants_
libcamera::ipa::CameraSensorHelper::gainConstants_ 

protected 
The analogue gain parameters used for calculation.
The analogue gain is calculated through a formula, and its parameters are sensor specific. Use this variable to store the values at init time.
The documentation for this class was generated from the following files: