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-rw-r--r--src/ipa/libipa/lsc_polynomial.cpp81
-rw-r--r--src/ipa/libipa/lsc_polynomial.h105
-rw-r--r--src/ipa/libipa/meson.build2
3 files changed, 188 insertions, 0 deletions
diff --git a/src/ipa/libipa/lsc_polynomial.cpp b/src/ipa/libipa/lsc_polynomial.cpp
new file mode 100644
index 00000000..f607d86c
--- /dev/null
+++ b/src/ipa/libipa/lsc_polynomial.cpp
@@ -0,0 +1,81 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2024, Ideas On Board
+ *
+ * Polynomial class to represent lens shading correction
+ */
+
+#include "lsc_polynomial.h"
+
+#include <libcamera/base/log.h>
+
+/**
+ * \file lsc_polynomial.h
+ * \brief LscPolynomial class
+ */
+
+namespace libcamera {
+
+LOG_DEFINE_CATEGORY(LscPolynomial)
+
+namespace ipa {
+
+/**
+ * \class LscPolynomial
+ * \brief Class for handling even polynomials used in lens shading correction
+ *
+ * Shading artifacts of camera lenses can be modeled using even radial
+ * polynomials. This class implements a polynomial with 5 coefficients which
+ * follows the definition of the FixVignetteRadial opcode in the Adobe DNG
+ * specification.
+ */
+
+/**
+ * \fn 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)
+ * \brief Construct a polynomial using the given coefficients
+ * \param cx Center-x relative to the image in normalized coordinates (0..1)
+ * \param cy Center-y relative to the image in normalized coordinates (0..1)
+ * \param k0 Coefficient of the polynomial
+ * \param k1 Coefficient of the polynomial
+ * \param k2 Coefficient of the polynomial
+ * \param k3 Coefficient of the polynomial
+ * \param k4 Coefficient of the polynomial
+ */
+
+/**
+ * \fn LscPolynomial::sampleAtNormalizedPixelPos(double x, double y)
+ * \brief Sample the polynomial at the given normalized pixel position
+ *
+ * This functions samples the polynomial at the given pixel position divided by
+ * the value returned by getM().
+ *
+ * \param x x position in normalized coordinates
+ * \param y y position in normalized coordinates
+ * \return The sampled value
+ */
+
+/**
+ * \fn LscPolynomial::getM()
+ * \brief Get the value m as described in the dng specification
+ *
+ * Returns m according to dng spec. m represents the Euclidean distance
+ * (in pixels) from the optical center to the farthest pixel in the
+ * image.
+ *
+ * \return The sampled value
+ */
+
+/**
+ * \fn LscPolynomial::setReferenceImageSize(const Size &size)
+ * \brief Set the reference image size
+ *
+ * Set the reference image size that is used for subsequent calls to getM() and
+ * sampleAtNormalizedPixelPos()
+ *
+ * \param size The size of the reference image
+ */
+
+} // namespace ipa
+} // namespace libcamera
diff --git a/src/ipa/libipa/lsc_polynomial.h b/src/ipa/libipa/lsc_polynomial.h
new file mode 100644
index 00000000..c898faeb
--- /dev/null
+++ b/src/ipa/libipa/lsc_polynomial.h
@@ -0,0 +1,105 @@
+/* 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 */
diff --git a/src/ipa/libipa/meson.build b/src/ipa/libipa/meson.build
index 3740178b..e78cbcd6 100644
--- a/src/ipa/libipa/meson.build
+++ b/src/ipa/libipa/meson.build
@@ -8,6 +8,7 @@ libipa_headers = files([
'fc_queue.h',
'histogram.h',
'interpolator.h',
+ 'lsc_polynomial.h',
'matrix.h',
'module.h',
'pwl.h',
@@ -22,6 +23,7 @@ libipa_sources = files([
'fc_queue.cpp',
'histogram.cpp',
'interpolator.cpp',
+ 'lsc_polynomial.cpp',
'matrix.cpp',
'module.cpp',
'pwl.cpp',