[PATCH v7 2/3] ipa: libipa: Add MatrixInterpolator class
Kieran Bingham
kieran.bingham at ideasonboard.com
Tue Jun 11 16:14:45 CEST 2024
Quoting Paul Elder (2024-06-11 15:02:06)
> Add a class to encapsulate the functionality of fetching a matrix based
> on an integer key, and interpolating if there is no exact match. This is
> expected to be used by both color correction matrices / crosstalk
> correction as well as lens shading correction.
>
> A cache is included only for exact matches of the key. The caller is
> expected to decide the tolererance for rounding.
>
> Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
> Reviewed-by: Stefan Klug <stefan.klug at ideasonboard.com>
>
> ---
> Changes in v7:
> - remove cache
> - fix copyright and license
Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
>
> Changes in v6:
> - fix doxygen
>
> Changes in v5:
> - improve documentation
> - replace count() with find() != end() (in get())
> - add cache
>
> Changes in v4:
> - remove stray semicolons
> - read from the new yaml layout (which mirrors what we have at the
> moment for lsc), and add keys to make it more flexible
>
> Changes in v3:
> - add a constructor that takes a map of unsigned int -> matrix
> - s/unit/identity
> - clear matrices on reset and when reading from yaml
> - add assert at get()
>
> Changes in v2:
> - initialize to identity matrix
> - add a function to reset to identity matrix
> - other minor fixes
> ---
> src/ipa/libipa/matrix_interpolator.cpp | 110 ++++++++++++++++++++++
> src/ipa/libipa/matrix_interpolator.h | 124 +++++++++++++++++++++++++
> src/ipa/libipa/meson.build | 2 +
> 3 files changed, 236 insertions(+)
> create mode 100644 src/ipa/libipa/matrix_interpolator.cpp
> create mode 100644 src/ipa/libipa/matrix_interpolator.h
>
> diff --git a/src/ipa/libipa/matrix_interpolator.cpp b/src/ipa/libipa/matrix_interpolator.cpp
> new file mode 100644
> index 000000000000..04ca177f72c6
> --- /dev/null
> +++ b/src/ipa/libipa/matrix_interpolator.cpp
> @@ -0,0 +1,110 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2024, Paul Elder <paul.elder at ideasonboard.com>
> + *
> + * Helper class for interpolating maps of matrices
> + */
> +#include "matrix_interpolator.h"
> +
> +#include <algorithm>
> +#include <string>
> +
> +#include <libcamera/base/log.h>
> +
> +#include "libcamera/internal/yaml_parser.h"
> +
> +#include "matrix.h"
> +
> +/**
> + * \file matrix_interpolator.h
> + * \brief Helper class for interpolating maps of matrices
> + */
> +
> +namespace libcamera {
> +
> +LOG_DEFINE_CATEGORY(MatrixInterpolator)
> +
> +namespace ipa {
> +
> +/**
> + * \class MatrixInterpolator
> + * \brief Class for storing, retrieving, and interpolating matrices
> + * \tparam T Type of numerical values to be stored in the matrices
> + * \tparam R Number of rows in the matrices
> + * \tparam C Number of columns in the matrices
> + *
> + * The main use case is to pass a map from color temperatures to corresponding
> + * matrices (eg. color correction), and then requesting a matrix for a specific
> + * color temperature. This class will abstract away the interpolation portion.
> + */
> +
> +/**
> + * \fn MatrixInterpolator::MatrixInterpolator(const std::map<unsigned int, Matrix<T, R, C>> &matrices)
> + * \brief Construct a matrix interpolator from a map of matrices
> + * \param matrices Map from which to construct the matrix interpolator
> + */
> +
> +/**
> + * \fn MatrixInterpolator::reset()
> + * \brief Reset the matrix interpolator content to a single identity matrix
> + */
> +
> +/**
> + * \fn int MatrixInterpolator<T, R, C>::readYaml()
> + * \brief Initialize an MatrixInterpolator instance from yaml
> + * \tparam T Type of data stored in the matrices
> + * \tparam R Number of rows of the matrices
> + * \tparam C Number of columns of the matrices
> + * \param[in] yaml The yaml object that contains the map of unsigned integers to matrices
> + * \param[in] key_name The name of the key in the yaml object
> + * \param[in] matrix_name The name of the matrix in the yaml object
> + *
> + * The yaml object is expected to be a list of maps. Each map has two or more
> + * pairs: one of \a key_name to the key value (usually color temperature), and
> + * one or more of \a matrix_name to the matrix. This is a bit difficult to
> + * explain, so here is an example (in python, as it is easier to parse than
> + * yaml):
> + * [
> + * {
> + * 'ct': 2860,
> + * 'ccm': [ 2.12089, -0.52461, -0.59629,
> + * -0.85342, 2.80445, -0.95103,
> + * -0.26897, -1.14788, 2.41685 ],
> + * 'offsets': [ 0, 0, 0 ]
> + * },
> + *
> + * {
> + * 'ct': 2960,
> + * 'ccm': [ 2.26962, -0.54174, -0.72789,
> + * -0.77008, 2.60271, -0.83262,
> + * -0.26036, -1.51254, 2.77289 ],
> + * 'offsets': [ 0, 0, 0 ]
> + * },
> + *
> + * {
> + * 'ct': 3603,
> + * 'ccm': [ 2.18644, -0.66148, -0.52496,
> + * -0.77828, 2.69474, -0.91645,
> + * -0.25239, -0.83059, 2.08298 ],
> + * 'offsets': [ 0, 0, 0 ]
> + * },
> + * ]
> + *
> + * In this case, \a key_name would be 'ct', and \a matrix_name can be either
> + * 'ccm' or 'offsets'. This way multiple matrix interpolators can be defined in
> + * one set of color temperature ranges in the tuning file, and they can be
> + * retrieved separately with the \a matrix_name parameter.
> + *
> + * \return Zero on success, negative error code otherwise
> + */
> +
> +/**
> + * \fn Matrix<T, R, C> MatrixInterpolator<T, R, C>::get(unsigned int key)
> + * \brief Retrieve a matrix from the list of matrices, interpolating if necessary
> + * \param[in] key The unsigned integer key of the matrix to retrieve
> + * \return The matrix corresponding to the color temperature
> + */
> +
> +} /* namespace ipa */
> +
> +} /* namespace libcamera */
> diff --git a/src/ipa/libipa/matrix_interpolator.h b/src/ipa/libipa/matrix_interpolator.h
> new file mode 100644
> index 000000000000..36827faec9ae
> --- /dev/null
> +++ b/src/ipa/libipa/matrix_interpolator.h
> @@ -0,0 +1,124 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2024, Paul Elder <paul.elder at ideasonboard.com>
> + *
> + * Helper class for interpolating maps of matrices
> + */
> +
> +#pragma once
> +
> +#include <algorithm>
> +#include <map>
> +#include <string>
> +#include <tuple>
> +
> +#include <libcamera/base/log.h>
> +
> +#include "libcamera/internal/yaml_parser.h"
> +
> +#include "matrix.h"
> +
> +namespace libcamera {
> +
> +LOG_DECLARE_CATEGORY(MatrixInterpolator)
> +
> +namespace ipa {
> +
> +#ifndef __DOXYGEN__
> +template<typename T, unsigned int R, unsigned int C,
> + std::enable_if_t<std::is_arithmetic_v<T>> * = nullptr>
> +#else
> +template<typename T, unsigned int R, unsigned int C>
> +#endif /* __DOXYGEN__ */
> +class MatrixInterpolator
> +{
> +public:
> + MatrixInterpolator()
> + {
> + reset();
> + }
> +
> + MatrixInterpolator(const std::map<unsigned int, Matrix<T, R, C>> &matrices)
> + {
> + for (const auto &pair : matrices)
> + matrices_[pair.first] = pair.second;
> + }
> +
> + ~MatrixInterpolator() {}
> +
> + void reset()
> + {
> + Matrix<T, R, C> identity;
> + matrices_.clear();
> + matrices_[0] = identity;
> + }
> +
> + int readYaml(const libcamera::YamlObject &yaml,
> + const std::string &key_name,
> + const std::string &matrix_name)
> + {
> + int ret;
> +
> + matrices_.clear();
> +
> + if (!yaml.isList()) {
> + LOG(MatrixInterpolator, Error) << "yaml object must be a list";
> + return -EINVAL;
> + }
> +
> + for (const auto &value : yaml.asList()) {
> + unsigned int ct = std::stoul(value[key_name].get<std::string>(""));
> + Matrix<T, R, C> matrix;
> + if ((ret = matrix.readYaml(value[matrix_name])) < 0) {
> + LOG(MatrixInterpolator, Error) << "Failed to read matrix";
> + return ret;
> + }
> +
> + matrices_[ct] = matrix;
> +
> + LOG(MatrixInterpolator, Debug)
> + << "Read matrix '" << matrix_name << "' for key '"
> + << key_name << "' " << ct << ": "
> + << matrices_[ct].toString();
> + }
> +
> + if (matrices_.size() < 1) {
> + LOG(MatrixInterpolator, Error) << "Need at least one matrix";
> + return -EINVAL;
> + }
> +
> + return 0;
> + }
> +
> + Matrix<T, R, C> get(unsigned int ct)
> + {
> + ASSERT(matrices_.size() > 0);
> +
> + if (matrices_.size() == 1 ||
> + ct <= matrices_.begin()->first)
> + return matrices_.begin()->second;
> +
> + if (ct >= matrices_.rbegin()->first)
> + return matrices_.rbegin()->second;
> +
> + if (matrices_.find(ct) != matrices_.end())
> + return matrices_[ct];
> +
> + /* The above four guarantee that this will succeed */
> + auto iter = matrices_.upper_bound(ct);
> + unsigned int ctUpper = iter->first;
> + unsigned int ctLower = (--iter)->first;
> +
> + double lambda = (ct - ctLower) / static_cast<double>(ctUpper - ctLower);
> + Matrix<T, R, C> ret =
> + lambda * matrices_[ctUpper] + (1.0 - lambda) * matrices_[ctLower];
> + return ret;
> + }
> +
> +private:
> + std::map<unsigned int, Matrix<T, R, C>> matrices_;
> +};
> +
> +} /* namespace ipa */
> +
> +} /* namespace libcamera */
> diff --git a/src/ipa/libipa/meson.build b/src/ipa/libipa/meson.build
> index 067d0d273e0a..a3349f0dd2c2 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',
> 'matrix.h',
> + 'matrix_interpolator.h',
> 'module.h',
> ])
>
> @@ -19,6 +20,7 @@ libipa_sources = files([
> 'fc_queue.cpp',
> 'histogram.cpp',
> 'matrix.cpp',
> + 'matrix_interpolator.cpp',
> 'module.cpp',
> ])
>
> --
> 2.39.2
>
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