[PATCH v5 13/18] libcamera: software_isp: Move black level to an algorithm module
Laurent Pinchart
laurent.pinchart at ideasonboard.com
Fri Sep 6 23:18:07 CEST 2024
On Fri, Sep 06, 2024 at 04:01:13PM +0200, Milan Zamazal wrote:
> Laurent Pinchart writes:
> > On Fri, Sep 06, 2024 at 11:42:05AM +0200, Milan Zamazal wrote:
> >> Laurent Pinchart writes:
> >> > On Fri, Aug 30, 2024 at 09:25:49AM +0200, Milan Zamazal wrote:
> >> >> The black level determination, already present as a separate class, can
> >> >> be moved to the prepared Algorithm processing structure. It is the
> >> >> first of the current software ISP algorithms that is called in the stats
> >> >> processing sequence, which means it is also the first one that should be
> >> >> moved to the new structure. Stats processing starts with calling
> >> >> Algorithm-based processing so the call order of the algorithms is
> >> >> retained.
> >> >>
> >> >> Movement of this algorithm is relatively straightforward because all it
> >> >> does is processing stats.
> >> >>
> >> >> The comment about getting black level from the tuning files is dropped.
> >> >> The black level will be taken from CameraSensorHelper if available and
> >> >> that will be implemented in one of the followup patches.
> >> >>
> >> >> Black level is now recomputed on each stats processing. In a future
> >> >> patch, after DelayedControls are used, this will be changed to recompute
> >> >> the black level only after exposure/gain changes.
> >> >>
> >> >> Signed-off-by: Milan Zamazal <mzamazal at redhat.com>
> >> >> Reviewed-by: Umang Jain <umang.jain at ideasonboard.com>
> >> >> ---
> >> >> src/ipa/simple/algorithms/blc.cpp | 71 ++++++++++++++++++++
> >> >> src/ipa/simple/algorithms/blc.h | 37 +++++++++++
> >> >> src/ipa/simple/algorithms/meson.build | 1 +
> >> >> src/ipa/simple/black_level.cpp | 93 ---------------------------
> >> >> src/ipa/simple/black_level.h | 33 ----------
> >> >> src/ipa/simple/data/uncalibrated.yaml | 1 +
> >> >> src/ipa/simple/ipa_context.cpp | 8 +++
> >> >> src/ipa/simple/ipa_context.h | 5 ++
> >> >> src/ipa/simple/meson.build | 1 -
> >> >> src/ipa/simple/soft_simple.cpp | 8 +--
> >> >> 10 files changed, 125 insertions(+), 133 deletions(-)
> >> >> create mode 100644 src/ipa/simple/algorithms/blc.cpp
> >> >> create mode 100644 src/ipa/simple/algorithms/blc.h
> >> >> delete mode 100644 src/ipa/simple/black_level.cpp
> >> >> delete mode 100644 src/ipa/simple/black_level.h
> >> >>
> >> >> diff --git a/src/ipa/simple/algorithms/blc.cpp b/src/ipa/simple/algorithms/blc.cpp
> >> >> new file mode 100644
> >> >> index 00000000..3b73d830
> >> >> --- /dev/null
> >> >> +++ b/src/ipa/simple/algorithms/blc.cpp
> >> >> @@ -0,0 +1,71 @@
> >> >> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> >> >> +/*
> >> >> + * Copyright (C) 2024, Red Hat Inc.
> >> >> + *
> >> >> + * Black level handling
> >> >> + */
> >> >> +
> >> >> +#include "blc.h"
> >> >> +
> >> >> +#include <numeric>
> >> >> +
> >> >> +#include <libcamera/base/log.h>
> >> >> +
> >> >> +namespace libcamera {
> >> >> +
> >> >> +namespace ipa::soft::algorithms {
> >> >> +
> >> >> +LOG_DEFINE_CATEGORY(IPASoftBL)
> >> >> +
> >> >> +BlackLevel::BlackLevel()
> >> >> +{
> >> >> +}
> >> >> +
> >> >> +int BlackLevel::init(IPAContext &context,
> >> >> + [[maybe_unused]] const YamlObject &tuningData)
> >> >> +{
> >> >> + context.activeState.black.level = 255;
> >> >
> >> > Is init() the right place, shouldn't this be done in configure() ?
> >> > Setting the initial value in init() means that a new capture session
> >> > will not start with a reinitialized black level value.
> >>
> >> That should be fine as long as the sensor is the same, which I suppose
> >> is the case.
> >
> > Is it fine ? Should an application expect that the camera will start
> > with identical parameters for the first capture session and for all
> > subsequent ones ?
>
> I'm not sure. Since init() is what takes tuningData as a parameter, I'd
> think a new instance should be created any time something substantial
> changes (e.g. a different sensor is used). OTOH in the patch (posted
> separately) taking black level from CameraSensorHelper if available, I
> move the initialization from init() to configure() because this is where
> CameraSensorHelper is available in software ISP.
init() is meant to read parameters from the tuning file, and perform
one-time initialization of data that do not vary during the life time of
the camera. Here you're initializing the active state, which is then
modified by process(). The active state should be reinitialized with
each capture session to avoid leaking state between sessions. Actually,
if you look for instance at IPARkISP1::configure(), you will see
/* Clear the IPA context before the streaming session. */
context_.configuration = {};
context_.activeState = {};
context_.frameContexts.clear();
Now, I think there are use cases for retaining some state between
sessions, to speed up convergence of algorithms, but I think that should
be designed and built on top of a base where the state is cleared,
instead of leaking the state between sessions in an uncontrolled way.
> In any case, moving it to configure() right now doesn't harm and I can
> do it in v7 (together with moving the gamma initialization).
>
> >> >> + return 0;
> >> >> +}
> >> >> +
> >> >> +void BlackLevel::process(IPAContext &context,
> >> >> + [[maybe_unused]] const uint32_t frame,
> >> >> + [[maybe_unused]] IPAFrameContext &frameContext,
> >> >> + const SwIspStats *stats,
> >> >> + [[maybe_unused]] ControlList &metadata)
> >> >> +{
> >> >> + const SwIspStats::Histogram &histogram = stats->yHistogram;
> >> >> +
> >> >> + /*
> >> >> + * The constant is selected to be "good enough", not overly conservative or
> >> >> + * aggressive. There is no magic about the given value.
> >> >
> >> > Please reflow to 80 columns.
> >> >
> >> >> + */
> >> >> + constexpr float ignoredPercentage_ = 0.02;
> >> >
> >> > It's not a member variable, so no trailing underscore.
> >> >
> >> >> + const unsigned int total =
> >> >> + std::accumulate(begin(histogram), end(histogram), 0);
> >> >> + const unsigned int pixelThreshold = ignoredPercentage_ * total;
> >> >> + const unsigned int histogramRatio = 256 / SwIspStats::kYHistogramSize;
> >> >> + const unsigned int currentBlackIdx =
> >> >> + context.activeState.black.level / histogramRatio;
> >> >> +
> >> >> + for (unsigned int i = 0, seen = 0;
> >> >> + i < currentBlackIdx && i < SwIspStats::kYHistogramSize;
> >> >> + i++) {
> >> >> + seen += histogram[i];
> >> >> + if (seen >= pixelThreshold) {
> >> >> + context.activeState.black.level = i * histogramRatio;
> >> >> + LOG(IPASoftBL, Debug)
> >> >> + << "Auto-set black level: "
> >> >> + << i << "/" << SwIspStats::kYHistogramSize
> >> >> + << " (" << 100 * (seen - histogram[i]) / total << "% below, "
> >> >> + << 100 * seen / total << "% at or below)";
> >> >> + break;
> >> >> + }
> >> >> + };
> >> >> +}
> >> >> +
> >> >> +REGISTER_IPA_ALGORITHM(BlackLevel, "BlackLevel")
> >> >> +
> >> >> +} /* namespace ipa::soft::algorithms */
> >> >> +
> >> >> +} /* namespace libcamera */
> >> >> diff --git a/src/ipa/simple/algorithms/blc.h b/src/ipa/simple/algorithms/blc.h
> >> >> new file mode 100644
> >> >> index 00000000..2f73db52
> >> >> --- /dev/null
> >> >> +++ b/src/ipa/simple/algorithms/blc.h
> >> >> @@ -0,0 +1,37 @@
> >> >> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> >> >> +/*
> >> >> + * Copyright (C) 2024, Red Hat Inc.
> >> >> + *
> >> >> + * Black level handling
> >> >> + */
> >> >> +
> >> >> +#pragma once
> >> >> +
> >> >> +#include <libcamera/controls.h>
> >> >> +
> >> >> +#include "libcamera/internal/software_isp/swisp_stats.h"
> >> >> +
> >> >> +#include "algorithm.h"
> >> >> +#include "ipa_context.h"
> >> >
> >> > I think you can drop controls.h, swisp_stats.h and ipa_context.h.
> >> > They're included only for classes and structures that are part of the
> >> > Algorithm class API, so they're guaranteed to be included through
> >> > algorithm.h.
> >> >
> >> >> +
> >> >> +namespace libcamera {
> >> >> +
> >> >> +namespace ipa::soft::algorithms {
> >> >> +
> >> >> +class BlackLevel : public Algorithm
> >> >> +{
> >> >> +public:
> >> >> + BlackLevel();
> >> >> + ~BlackLevel() = default;
> >> >> +
> >> >> + int init(IPAContext &context, const YamlObject &tuningData)
> >> >> + override;
> >> >> + void process(IPAContext &context, const uint32_t frame,
> >> >> + IPAFrameContext &frameContext,
> >> >> + const SwIspStats *stats,
> >> >> + ControlList &metadata) override;
> >> >> +};
> >> >> +
> >> >> +} /* namespace ipa::soft::algorithms */
> >> >> +
> >> >> +} /* namespace libcamera */
> >> >> diff --git a/src/ipa/simple/algorithms/meson.build b/src/ipa/simple/algorithms/meson.build
> >> >> index 31d26e43..1f63c220 100644
> >> >> --- a/src/ipa/simple/algorithms/meson.build
> >> >> +++ b/src/ipa/simple/algorithms/meson.build
> >> >> @@ -1,4 +1,5 @@
> >> >> # SPDX-License-Identifier: CC0-1.0
> >> >>
> >> >> soft_simple_ipa_algorithms = files([
> >> >> + 'blc.cpp',
> >> >> ])
> >> >> diff --git a/src/ipa/simple/black_level.cpp b/src/ipa/simple/black_level.cpp
> >> >> deleted file mode 100644
> >> >> index 37e0109c..00000000
> >> >> --- a/src/ipa/simple/black_level.cpp
> >> >> +++ /dev/null
> >> >> @@ -1,93 +0,0 @@
> >> >> -/* SPDX-License-Identifier: LGPL-2.1-or-later */
> >> >> -/*
> >> >> - * Copyright (C) 2024, Red Hat Inc.
> >> >> - *
> >> >> - * black level handling
> >> >> - */
> >> >> -
> >> >> -#include "black_level.h"
> >> >> -
> >> >> -#include <numeric>
> >> >> -
> >> >> -#include <libcamera/base/log.h>
> >> >> -
> >> >> -namespace libcamera {
> >> >> -
> >> >> -LOG_DEFINE_CATEGORY(IPASoftBL)
> >> >> -
> >> >> -namespace ipa::soft {
> >> >> -
> >> >> -/**
> >> >> - * \class BlackLevel
> >> >> - * \brief Object providing black point level for software ISP
> >> >> - *
> >> >> - * Black level can be provided in hardware tuning files or, if no tuning file is
> >> >> - * available for the given hardware, guessed automatically, with less accuracy.
> >> >> - * As tuning files are not yet implemented for software ISP, BlackLevel
> >> >> - * currently provides only guessed black levels.
> >> >> - *
> >> >> - * This class serves for tracking black level as a property of the underlying
> >> >> - * hardware, not as means of enhancing a particular scene or image.
> >> >> - *
> >> >> - * The class is supposed to be instantiated for the given camera stream.
> >> >> - * The black level can be retrieved using BlackLevel::get() method. It is
> >> >> - * initially 0 and may change when updated using BlackLevel::update() method.
> >> >> - */
> >> >> -
> >> >> -BlackLevel::BlackLevel()
> >> >> - : blackLevel_(255), blackLevelSet_(false)
> >> >> -{
> >> >> -}
> >> >> -
> >> >> -/**
> >> >> - * \brief Return the current black level
> >> >> - *
> >> >> - * \return The black level, in the range from 0 (minimum) to 255 (maximum).
> >> >> - * If the black level couldn't be determined yet, return 0.
> >> >> - */
> >> >> -uint8_t BlackLevel::get() const
> >> >> -{
> >> >> - return blackLevelSet_ ? blackLevel_ : 0;
> >> >> -}
> >> >> -
> >> >> -/**
> >> >> - * \brief Update black level from the provided histogram
> >> >> - * \param[in] yHistogram The histogram to be used for updating black level
> >> >> - *
> >> >> - * The black level is property of the given hardware, not image. It is updated
> >> >> - * only if it has not been yet set or if it is lower than the lowest value seen
> >> >> - * so far.
> >> >> - */
> >> >> -void BlackLevel::update(SwIspStats::Histogram &yHistogram)
> >> >> -{
> >> >> - /*
> >> >> - * The constant is selected to be "good enough", not overly conservative or
> >> >> - * aggressive. There is no magic about the given value.
> >> >> - */
> >> >> - constexpr float ignoredPercentage_ = 0.02;
> >> >> - const unsigned int total =
> >> >> - std::accumulate(begin(yHistogram), end(yHistogram), 0);
> >> >> - const unsigned int pixelThreshold = ignoredPercentage_ * total;
> >> >> - const unsigned int histogramRatio = 256 / SwIspStats::kYHistogramSize;
> >> >> - const unsigned int currentBlackIdx = blackLevel_ / histogramRatio;
> >> >> -
> >> >> - for (unsigned int i = 0, seen = 0;
> >> >> - i < currentBlackIdx && i < SwIspStats::kYHistogramSize;
> >> >> - i++) {
> >> >> - seen += yHistogram[i];
> >> >> - if (seen >= pixelThreshold) {
> >> >> - blackLevel_ = i * histogramRatio;
> >> >> - blackLevelSet_ = true;
> >> >> - LOG(IPASoftBL, Debug)
> >> >> - << "Auto-set black level: "
> >> >> - << i << "/" << SwIspStats::kYHistogramSize
> >> >> - << " (" << 100 * (seen - yHistogram[i]) / total << "% below, "
> >> >> - << 100 * seen / total << "% at or below)";
> >> >> - break;
> >> >> - }
> >> >> - };
> >> >> -}
> >> >> -
> >> >> -} /* namespace ipa::soft */
> >> >> -
> >> >> -} /* namespace libcamera */
> >> >> diff --git a/src/ipa/simple/black_level.h b/src/ipa/simple/black_level.h
> >> >> deleted file mode 100644
> >> >> index a04230c9..00000000
> >> >> --- a/src/ipa/simple/black_level.h
> >> >> +++ /dev/null
> >> >> @@ -1,33 +0,0 @@
> >> >> -/* SPDX-License-Identifier: LGPL-2.1-or-later */
> >> >> -/*
> >> >> - * Copyright (C) 2024, Red Hat Inc.
> >> >> - *
> >> >> - * black level handling
> >> >> - */
> >> >> -
> >> >> -#pragma once
> >> >> -
> >> >> -#include <array>
> >> >> -#include <stdint.h>
> >> >> -
> >> >> -#include "libcamera/internal/software_isp/swisp_stats.h"
> >> >> -
> >> >> -namespace libcamera {
> >> >> -
> >> >> -namespace ipa::soft {
> >> >> -
> >> >> -class BlackLevel
> >> >> -{
> >> >> -public:
> >> >> - BlackLevel();
> >> >> - uint8_t get() const;
> >> >> - void update(SwIspStats::Histogram &yHistogram);
> >> >> -
> >> >> -private:
> >> >> - uint8_t blackLevel_;
> >> >> - bool blackLevelSet_;
> >> >> -};
> >> >> -
> >> >> -} /* namespace ipa::soft */
> >> >> -
> >> >> -} /* namespace libcamera */
> >> >> diff --git a/src/ipa/simple/data/uncalibrated.yaml b/src/ipa/simple/data/uncalibrated.yaml
> >> >> index 2cdc39a8..e0d03d96 100644
> >> >> --- a/src/ipa/simple/data/uncalibrated.yaml
> >> >> +++ b/src/ipa/simple/data/uncalibrated.yaml
> >> >> @@ -3,4 +3,5 @@
> >> >> ---
> >> >> version: 1
> >> >> algorithms:
> >> >> + - BlackLevel:
> >> >> ...
> >> >> diff --git a/src/ipa/simple/ipa_context.cpp b/src/ipa/simple/ipa_context.cpp
> >> >> index 3c1c7262..268cff32 100644
> >> >> --- a/src/ipa/simple/ipa_context.cpp
> >> >> +++ b/src/ipa/simple/ipa_context.cpp
> >> >> @@ -50,4 +50,12 @@ namespace libcamera::ipa::soft {
> >> >> * \brief The current state of IPA algorithms
> >> >> */
> >> >>
> >> >> +/**
> >> >> + * \var IPAActiveState::black
> >> >> + * \brief Context for the Black Level algorithm
> >> >> + *
> >> >> + * \var IPAActiveState::black.level
> >> >> + * \brief Current determined black level
> >> >> + */
> >> >> +
> >> >> } /* namespace libcamera::ipa::soft */
> >> >> diff --git a/src/ipa/simple/ipa_context.h b/src/ipa/simple/ipa_context.h
> >> >> index e7d8b8df..22156569 100644
> >> >> --- a/src/ipa/simple/ipa_context.h
> >> >> +++ b/src/ipa/simple/ipa_context.h
> >> >> @@ -7,6 +7,8 @@
> >> >>
> >> >> #pragma once
> >> >>
> >> >> +#include <stdint.h>
> >> >> +
> >> >> #include <libipa/fc_queue.h>
> >> >>
> >> >> namespace libcamera {
> >> >> @@ -17,6 +19,9 @@ struct IPASessionConfiguration {
> >> >> };
> >> >>
> >> >> struct IPAActiveState {
> >> >> + struct {
> >> >> + uint8_t level;
> >> >> + } black;
> >> >
> >> > How about naming this blc ?
> >> >
> >> > Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> >> >
> >> >> };
> >> >>
> >> >> struct IPAFrameContext : public FrameContext {
> >> >> diff --git a/src/ipa/simple/meson.build b/src/ipa/simple/meson.build
> >> >> index dcd7c70a..2f9f15f4 100644
> >> >> --- a/src/ipa/simple/meson.build
> >> >> +++ b/src/ipa/simple/meson.build
> >> >> @@ -8,7 +8,6 @@ ipa_name = 'ipa_soft_simple'
> >> >> soft_simple_sources = files([
> >> >> 'ipa_context.cpp',
> >> >> 'soft_simple.cpp',
> >> >> - 'black_level.cpp',
> >> >> ])
> >> >>
> >> >> soft_simple_sources += soft_simple_ipa_algorithms
> >> >> diff --git a/src/ipa/simple/soft_simple.cpp b/src/ipa/simple/soft_simple.cpp
> >> >> index 4b9201dc..a1bd2f0c 100644
> >> >> --- a/src/ipa/simple/soft_simple.cpp
> >> >> +++ b/src/ipa/simple/soft_simple.cpp
> >> >> @@ -29,7 +29,6 @@
> >> >>
> >> >> #include "libipa/camera_sensor_helper.h"
> >> >>
> >> >> -#include "black_level.h"
> >> >> #include "module.h"
> >> >>
> >> >> namespace libcamera {
> >> >> @@ -61,7 +60,7 @@ class IPASoftSimple : public ipa::soft::IPASoftInterface, public Module
> >> >> {
> >> >> public:
> >> >> IPASoftSimple()
> >> >> - : params_(nullptr), stats_(nullptr), blackLevel_(BlackLevel()),
> >> >> + : params_(nullptr), stats_(nullptr),
> >> >> context_({ {}, {}, { kMaxFrameContexts } }),
> >> >> ignoreUpdates_(0)
> >> >> {
> >> >> @@ -93,7 +92,6 @@ private:
> >> >> SwIspStats *stats_;
> >> >> std::unique_ptr<CameraSensorHelper> camHelper_;
> >> >> ControlInfoMap sensorInfoMap_;
> >> >> - BlackLevel blackLevel_;
> >> >>
> >> >> static constexpr unsigned int kGammaLookupSize = 1024;
> >> >> std::array<uint8_t, kGammaLookupSize> gammaTable_;
> >> >> @@ -303,9 +301,7 @@ void IPASoftSimple::processStats(const uint32_t frame,
> >> >> algo->process(context_, frame, frameContext, stats_, metadata);
> >> >>
> >> >> SwIspStats::Histogram histogram = stats_->yHistogram;
> >> >> - if (ignoreUpdates_ > 0)
> >> >> - blackLevel_.update(histogram);
> >> >> - const uint8_t blackLevel = blackLevel_.get();
> >> >> + const uint8_t blackLevel = context_.activeState.black.level;
> >> >>
> >> >> /*
> >> >> * Black level must be subtracted to get the correct AWB ratios, they
--
Regards,
Laurent Pinchart
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