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lsc_polynomial.h
Go to the documentation of this file.
/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2024, Ideas On Board
*
* Helper for radial polynomial used in lens shading correction.
*/
#pragma once
#include <algorithm>
#include <array>
#include <assert.h>
#include <cmath>
#include <libcamera/base/log.h>
#include <libcamera/base/span.h>
#include "libcamera/internal/yaml_parser.h"
namespace libcamera {
LOG_DECLARE_CATEGORY(LscPolynomial)
namespace ipa {
class LscPolynomial
{
public:
LscPolynomial(double cx = 0.0, double cy = 0.0, double k0 = 0.0,
double k1 = 0.0, double k2 = 0.0, double k3 = 0.0,
double k4 = 0.0)
: cx_(cx), cy_(cy), cnx_(0), cny_(0),
coefficients_({ k0, k1, k2, k3, k4 })
{
}
double sampleAtNormalizedPixelPos(double x, double y) const
{
double dx = x - cnx_;
double dy = y - cny_;
double r = sqrt(dx * dx + dy * dy);
double res = 1.0;
for (unsigned int i = 0; i < coefficients_.size(); i++) {
res += coefficients_[i] * std::pow(r, (i + 1) * 2);
}
return res;
}
double getM() const
{
double cpx = imageSize_.width * cx_;
double cpy = imageSize_.height * cy_;
double mx = std::max(cpx, std::fabs(imageSize_.width - cpx));
double my = std::max(cpy, std::fabs(imageSize_.height - cpy));
return sqrt(mx * mx + my * my);
}
void setReferenceImageSize(const Size &size)
{
assert(!size.isNull());
imageSize_ = size;
/* Calculate normalized centers */
double m = getM();
cnx_ = (size.width * cx_) / m;
cny_ = (size.height * cy_) / m;
}
private:
double cx_;
double cy_;
double cnx_;
double cny_;
std::array<double, 5> coefficients_;
Size imageSize_;
};
} /* namespace ipa */
#ifndef __DOXYGEN__
template<>
struct YamlObject::Getter<ipa::LscPolynomial> {
std::optional<ipa::LscPolynomial> get(const YamlObject &obj) const
{
std::optional<double> cx = obj["cx"].get<double>();
std::optional<double> cy = obj["cy"].get<double>();
std::optional<double> k0 = obj["k0"].get<double>();
std::optional<double> k1 = obj["k1"].get<double>();
std::optional<double> k2 = obj["k2"].get<double>();
std::optional<double> k3 = obj["k3"].get<double>();
std::optional<double> k4 = obj["k4"].get<double>();
if (!(cx && cy && k0 && k1 && k2 && k3 && k4))
LOG(LscPolynomial, Error)
<< "Polynomial is missing a parameter";
return ipa::LscPolynomial(*cx, *cy, *k0, *k1, *k2, *k3, *k4);
}
};
#endif
} /* namespace libcamera */
libcamera::Size
Describe a two-dimensional size.
Definition geometry.h:51
libcamera::Size::width
unsigned int width
The Size width.
Definition geometry.h:63
libcamera::Size::height
unsigned int height
The Size height.
Definition geometry.h:64
libcamera::Size::isNull
bool isNull() const
Check if the size is null.
Definition geometry.h:66
libcamera::YamlObject::get
std::optional< T > get() const
Parse the YamlObject as a T value.
Definition yaml_parser.h:175
libcamera::ipa::LscPolynomial::setReferenceImageSize
void setReferenceImageSize(const Size &size)
Set the reference image size.
Definition lsc_polynomial.h:58
libcamera::ipa::LscPolynomial::LscPolynomial
LscPolynomial(double cx=0.0, double cy=0.0, double k0=0.0, double k1=0.0, double k2=0.0, double k3=0.0, double k4=0.0)
Construct a polynomial using the given coefficients.
Definition lsc_polynomial.h:28
libcamera::ipa::LscPolynomial::getM
double getM() const
Get the value m as described in the dng specification.
Definition lsc_polynomial.h:48
libcamera::ipa::LscPolynomial::sampleAtNormalizedPixelPos
double sampleAtNormalizedPixelPos(double x, double y) const
Sample the polynomial at the given normalized pixel position.
Definition lsc_polynomial.h:36
log.h
Logging infrastructure.
LOG_DECLARE_CATEGORY
#define LOG_DECLARE_CATEGORY(name)
Declare a category of log messages.
Definition log.h:51
LOG
#define LOG(category, severity)
Log a message.
Definition log.h:129
libcamera::ipa
The IPA (Image Processing Algorithm) namespace.
Definition af.cpp:58
libcamera
Top-level libcamera namespace.
Definition backtrace.h:17
yaml_parser.h
A YAML parser helper.