Stefan Klug
eb6edfb69e
Add a basic class to represent polynomials as specified in the DNG spec for vignetting correction. Signed-off-by: Stefan Klug <stefan.klug@ideasonboard.com> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
106 lines
2.4 KiB
C++
106 lines
2.4 KiB
C++
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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/*
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* Copyright (C) 2024, Ideas On Board
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*
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* Helper for radial polynomial used in lens shading correction.
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*/
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#pragma once
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#include <algorithm>
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#include <array>
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#include <assert.h>
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#include <cmath>
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#include <libcamera/base/log.h>
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#include <libcamera/base/span.h>
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#include "libcamera/internal/yaml_parser.h"
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namespace libcamera {
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LOG_DECLARE_CATEGORY(LscPolynomial)
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namespace ipa {
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class LscPolynomial
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{
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public:
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LscPolynomial(double cx = 0.0, double cy = 0.0, double k0 = 0.0,
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double k1 = 0.0, double k2 = 0.0, double k3 = 0.0,
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double k4 = 0.0)
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: cx_(cx), cy_(cy), cnx_(0), cny_(0),
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coefficients_({ k0, k1, k2, k3, k4 })
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{
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}
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double sampleAtNormalizedPixelPos(double x, double y) const
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{
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double dx = x - cnx_;
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double dy = y - cny_;
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double r = sqrt(dx * dx + dy * dy);
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double res = 1.0;
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for (unsigned int i = 0; i < coefficients_.size(); i++) {
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res += coefficients_[i] * std::pow(r, (i + 1) * 2);
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}
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return res;
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}
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double getM() const
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{
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double cpx = imageSize_.width * cx_;
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double cpy = imageSize_.height * cy_;
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double mx = std::max(cpx, std::fabs(imageSize_.width - cpx));
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double my = std::max(cpy, std::fabs(imageSize_.height - cpy));
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return sqrt(mx * mx + my * my);
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}
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void setReferenceImageSize(const Size &size)
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{
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assert(!size.isNull());
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imageSize_ = size;
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/* Calculate normalized centers */
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double m = getM();
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cnx_ = (size.width * cx_) / m;
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cny_ = (size.height * cy_) / m;
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}
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private:
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double cx_;
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double cy_;
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double cnx_;
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double cny_;
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std::array<double, 5> coefficients_;
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Size imageSize_;
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};
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} /* namespace ipa */
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#ifndef __DOXYGEN__
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template<>
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struct YamlObject::Getter<ipa::LscPolynomial> {
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std::optional<ipa::LscPolynomial> get(const YamlObject &obj) const
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{
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std::optional<double> cx = obj["cx"].get<double>();
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std::optional<double> cy = obj["cy"].get<double>();
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std::optional<double> k0 = obj["k0"].get<double>();
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std::optional<double> k1 = obj["k1"].get<double>();
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std::optional<double> k2 = obj["k2"].get<double>();
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std::optional<double> k3 = obj["k3"].get<double>();
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std::optional<double> k4 = obj["k4"].get<double>();
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if (!(cx && cy && k0 && k1 && k2 && k3 && k4))
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LOG(LscPolynomial, Error)
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<< "Polynomial is missing a parameter";
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return ipa::LscPolynomial(*cx, *cy, *k0, *k1, *k2, *k3, *k4);
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}
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};
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#endif
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} /* namespace libcamera */
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