[PATCH v2 7/9] ipa: libipa: Add lsc polynomial class
Paul Elder
paul.elder at ideasonboard.com
Fri Sep 13 13:07:04 CEST 2024
On Fri, Sep 13, 2024 at 09:57:25AM +0200, Stefan Klug wrote:
> Add a basic class to represent polynomials as specified in the DNG spec
> for vignetting correction.
>
> Signed-off-by: Stefan Klug <stefan.klug at ideasonboard.com>
> ---
> src/ipa/libipa/lsc_polynomial.cpp | 81 +++++++++++++++++++++++
> src/ipa/libipa/lsc_polynomial.h | 104 ++++++++++++++++++++++++++++++
> src/ipa/libipa/meson.build | 2 +
> 3 files changed, 187 insertions(+)
> create mode 100644 src/ipa/libipa/lsc_polynomial.cpp
> create mode 100644 src/ipa/libipa/lsc_polynomial.h
>
> diff --git a/src/ipa/libipa/lsc_polynomial.cpp b/src/ipa/libipa/lsc_polynomial.cpp
> new file mode 100644
> index 000000000000..abbbcb6a724c
> --- /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
> + *
> + * Polynomal class to represent lens shading correction
s/Polynomal/Polynomial/
> + */
> +
> +#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 polynomial 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 000000000000..890199017590
> --- /dev/null
> +++ b/src/ipa/libipa/lsc_polynomial.h
> @@ -0,0 +1,104 @@
> +/* 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),
> + coefficients_({ k0, k1, k2, k3, k4 })
> + {
> + }
> +
> + double sampleAtNormalizedPixelPos(double x, double y) const
> + {
> + double dx = x - cnx_;
> + double dy = y - cny_;
Should cn{x,y}_ be initialized above?
Otherwise it looks fine.
Paul
> + 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)
> + {
> + 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 3740178b2909..e78cbcd63633 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',
> --
> 2.43.0
>
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