[PATCH 2/3] ipa: rkisp1: Add Lux algorithm module

[Dan Scally]

Hi Paul

On 12/04/2024 10:16, Paul Elder wrote:
> Add a lux algorithm module to rkisp1 IPA for estimating the lux level of
> an image. This is reported in metadata, as well as saved in the frame
> context so that other algorithms (mainly AGC) can use its value. It does
> not set any controls.
>
> Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
> ---
>   src/ipa/rkisp1/algorithms/lux.cpp     | 76 +++++++++++++++++++++++++++
>   src/ipa/rkisp1/algorithms/lux.h       | 39 ++++++++++++++


Like Kieran, I also lean towards "this should just be a part of the Agc implementation" - it should 
only be a few lines added to ::process(). We could pass in the return value from estimateLuminance() 
rather than constructing a yHist too perhaps.

>   src/ipa/rkisp1/algorithms/meson.build |  1 +
>   src/ipa/rkisp1/ipa_context.h          |  1 +
>   4 files changed, 117 insertions(+)
>   create mode 100644 src/ipa/rkisp1/algorithms/lux.cpp
>   create mode 100644 src/ipa/rkisp1/algorithms/lux.h
>
> diff --git a/src/ipa/rkisp1/algorithms/lux.cpp b/src/ipa/rkisp1/algorithms/lux.cpp
> new file mode 100644
> index 00000000..1816ddb2
> --- /dev/null
> +++ b/src/ipa/rkisp1/algorithms/lux.cpp
> @@ -0,0 +1,76 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2024, Ideas On Board
> + *
> + * lux.cpp - RkISP1 Lux control
> + */
> +
> +#include "lux.h"
> +
> +#include <algorithm>
> +#include <cmath>
> +
> +#include <libcamera/base/log.h>
> +
> +#include <libcamera/control_ids.h>
> +
> +#include "libcamera/internal/yaml_parser.h"
> +
> +#include "libipa/histogram.h"
> +#include "libipa/lux.h"
> +
> +/**
> + * \file lux.h
> + */
> +
> +namespace libcamera {
> +
> +namespace ipa::rkisp1::algorithms {
> +
> +/**
> + * \class Lux
> + * \brief RkISP1 Lux control
> + *
> + * The Lux algorithm is responsible for estimating the lux level of the image.
> + * It doesn't take or generate any controls, but it provides a lux level for
> + * other algorithms (such as AGC) to use.
> + */
> +
> +LOG_DEFINE_CATEGORY(RkISP1Lux)
> +
> +/**
> + * \copydoc libcamera::ipa::Algorithm::init
> + */
> +int Lux::init([[maybe_unused]] IPAContext &context, const YamlObject &tuningData)
> +{
> +	return lux_.readYaml(tuningData);
> +}
> +
> +/**
> + * \copydoc libcamera::ipa::Algorithm::process
> + */
> +void Lux::process(IPAContext &context,
> +		  [[maybe_unused]] const uint32_t frame,
> +		  IPAFrameContext &frameContext,
> +		  const rkisp1_stat_buffer *stats,
> +		  ControlList &metadata)
> +{
> +	utils::Duration exposureTime = context.configuration.sensor.lineDuration
> +				       * frameContext.sensor.exposure;
> +	double gain = frameContext.sensor.gain;
> +
> +	const rkisp1_cif_isp_stat *params = &stats->params;
> +	Histogram yHist = Histogram(Span<const uint32_t>(params->hist.hist_bins,
> +							 context.hw->numHistogramBins), 4);
> +
> +	/* todo Update this when we support aperture */
> +	double lux = lux_.process(gain, exposureTime, 1.0, yHist);
> +	frameContext.agc.lux = lux;
> +	metadata.set(controls::Lux, lux);
> +}
> +
> +REGISTER_IPA_ALGORITHM(Lux, "Lux")
> +
> +} /* namespace ipa::rkisp1::algorithms */
> +
> +} /* namespace libcamera */
> diff --git a/src/ipa/rkisp1/algorithms/lux.h b/src/ipa/rkisp1/algorithms/lux.h
> new file mode 100644
> index 00000000..ea98c291
> --- /dev/null
> +++ b/src/ipa/rkisp1/algorithms/lux.h
> @@ -0,0 +1,39 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2024, Ideas On Board
> + *
> + * lux.h - RkISP1 Lux control
> + */
> +
> +#pragma once
> +
> +#include <sys/types.h>
> +
> +#include "libcamera/internal/yaml_parser.h"
> +
> +#include "libipa/lux.h"
> +
> +#include "algorithm.h"
> +
> +namespace libcamera {
> +
> +namespace ipa::rkisp1::algorithms {
> +
> +class Lux : public Algorithm
> +{
> +public:
> +	Lux() = default;
> +	~Lux() = default;
> +
> +	int init(IPAContext &context, const YamlObject &tuningData) override;
> +	void process(IPAContext &context, const uint32_t frame,
> +		     IPAFrameContext &frameContext,
> +		     const rkisp1_stat_buffer *stats,
> +		     ControlList &metadata) override;
> +
> +private:
> +	ipa::Lux lux_;
> +};
> +
> +} /* namespace ipa::rkisp1::algorithms */
> +} /* namespace libcamera */
> diff --git a/src/ipa/rkisp1/algorithms/meson.build b/src/ipa/rkisp1/algorithms/meson.build
> index c9891e87..b0381d5f 100644
> --- a/src/ipa/rkisp1/algorithms/meson.build
> +++ b/src/ipa/rkisp1/algorithms/meson.build
> @@ -11,4 +11,5 @@ rkisp1_ipa_algorithms = files([
>       'filter.cpp',
>       'gsl.cpp',
>       'lsc.cpp',
> +    'lux.cpp',
>   ])
> diff --git a/src/ipa/rkisp1/ipa_context.h b/src/ipa/rkisp1/ipa_context.h
> index dc876da0..c39e0e9b 100644
> --- a/src/ipa/rkisp1/ipa_context.h
> +++ b/src/ipa/rkisp1/ipa_context.h
> @@ -118,6 +118,7 @@ struct IPAFrameContext : public FrameContext {
>   		int32_t exposureMode;
>   		int32_t constraintMode;
>   		utils::Duration maxShutterSpeed;
> +		double lux;
>   	} agc;
>   
>   	struct {