libcamera: libcamera::ipa Namespace Reference

libcamera v0.7.0 Supporting cameras in Linux since 2019

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libcamera::ipa Namespace Reference

The IPA (Image Processing Algorithm) namespace. More...

## Classes
class | AgcMeanLuminance
| A mean-based auto-exposure algorithm. More...
class | Algorithm
| The base class for all IPA algorithms. More...
class | AlgorithmFactoryBase
class | AlgorithmFactory
| Registration of Algorithm classes and creation of instances. More...
class | AwbResult
| The result of an AWB calculation. More...
class | AwbStats
| An abstraction class wrapping hardware-specific AWB statistics. More...
class | AwbAlgorithm
| A base class for auto white balance algorithms. More...
class | AwbBayes
| Implementation of a bayesian auto white balance algorithm. More...
class | AwbGrey
| A Grey world auto white balance algorithm. More...
class | CameraSensorHelper
| Base class for computing sensor tuning parameters using sensor-specific constants. More...
class | CameraSensorHelperFactoryBase
| Base class for camera sensor helper factories. More...
class | CameraSensorHelperFactory
| Registration of CameraSensorHelperFactory classes and creation of instances. More...
class | ExposureModeHelper
| Class for splitting exposure into exposure time and total gain. More...
class | FCQueue
| A support class for managing FrameContext instances in IPA modules. More...
struct | FrameContext
| Context for a frame. More...
class | Histogram
| The base class for creating histograms. More...
class | Interpolator
| Class for storing, retrieving, and interpolating objects. More...
class | LscPolynomial
| Class for handling even polynomials used in lens shading correction. More...
class | Lux
| Class that implements lux estimation. More...
class | Module
| The base class for all IPA modules. More...
class | Pwl
| Describe a univariate piecewise linear function in two-dimensional real space. More...
class | V4L2ParamsBlock
| Helper class that represents an ISP configuration block. More...
class | V4L2Params
| Helper class that represent an ISP configuration buffer. More...

## Functions
double | rec601LuminanceFromRGB (const RGB< double > &rgb)
| Estimate luminance from RGB values following ITU-R BT.601.
uint32_t | estimateCCT (const RGB< double > &rgb)
| Estimate correlated colour temperature from RGB color space input.
template<unsigned int I, unsigned int F, typename R, typename T>
constexpr R | floatingToFixedPoint (T number)
| Convert a floating point number to a fixed-point representation.
template<unsigned int I, unsigned int F, typename R, typename T>
constexpr R | fixedToFloatingPoint (T number)
| Convert a fixed-point number to a floating point representation.

## Variables
constexpr double | kSearchStep = 0.2
| Step size control for CT search.

## Detailed Description

The IPA (Image Processing Algorithm) namespace.

The IPA namespace groups all types specific to IPA modules. It serves as the top-level namespace for the IPA library libipa, and also contains module-specific namespaces for IPA modules.

## Function Documentation

## ◆ estimateCCT()

uint32_t libcamera::ipa::estimateCCT | ( | const RGB< double > & | rgb | ) |

Estimate correlated colour temperature from RGB color space input.

Parameters

  [in] | rgb | The RGB value

This function estimates the correlated color temperature RGB color space input. In physics and color science, the Planckian locus or black body locus is the path or locus that the color of an incandescent black body would take in a particular chromaticity space as the black body temperature changes.

If a narrow range of color temperatures is considered (those encapsulating daylight being the most practical case) one can approximate the Planckian locus in order to calculate the CCT in terms of chromaticity coordinates.

More detailed information can be found in: https://en.wikipedia.org/wiki/Color_temperature#Approximation

Returns
  The estimated color temperature

## ◆ fixedToFloatingPoint()

template<unsigned int I, unsigned int F, typename R, typename T>

R libcamera::ipa::fixedToFloatingPoint | ( | T | number | ) |
| constexpr

Convert a fixed-point number to a floating point representation.

Template Parameters

  I | Bit width of the integer part of the fixed-point
  F | Bit width of the fractional part of the fixed-point
  R | Return type of the floating point representation
  T | Input type of the fixed-point representation

Parameters

  number | The fixed point number to convert to floating point

Returns
  The converted value

## ◆ floatingToFixedPoint()

template<unsigned int I, unsigned int F, typename R, typename T>

R libcamera::ipa::floatingToFixedPoint | ( | T | number | ) |
| constexpr

Convert a floating point number to a fixed-point representation.

Template Parameters

  I | Bit width of the integer part of the fixed-point
  F | Bit width of the fractional part of the fixed-point
  R | Return type of the fixed-point representation
  T | Input type of the floating point representation

Parameters

  number | The floating point number to convert to fixed point

Returns
  The converted value

## ◆ rec601LuminanceFromRGB()

double libcamera::ipa::rec601LuminanceFromRGB | ( | const RGB< double > & | rgb | ) |

Estimate luminance from RGB values following ITU-R BT.601.

Parameters

  [in] | rgb | The RGB value

This function estimates a luminance value from a triplet of Red, Green and Blue values, following the formula defined by ITU-R Recommendation BT.601-7 which can be found at https://www.itu.int/rec/R-REC-BT.601

Returns
  The estimated luminance value