[PATCH v2 7/9] ipa: libipa: Add lsc polynomial class
Stefan Klug
stefan.klug at ideasonboard.com
Mon Sep 16 17:38:22 CEST 2024
Hi Paul,
Thank you for the review.
On Fri, Sep 13, 2024 at 01:07:04PM +0200, Paul Elder wrote:
> 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?
Yes, you're right. I'll initialize them in the constructor.
Cheers,
Stefan
>
>
> 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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