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libcamera: ipa: simple: Remove Lut algorithm

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The Lut algorithm is not really an algorithm.  Moreover, algorithms may
be enabled or disabled but with Lut disabled, nothing will work.

Let's move the construction of lookup tables to CPU debayering, where it
is used.  The implied and related changes are:

- DebayerParams is changed to contain the real params rather than lookup
  tables.
- contrastExp parameter introduced by GPU ISP is used for CPU ISP too.
- The params must be initialised so that debayering gets meaningful
  parameter values even when some algorithms are disabled.
- combinedMatrix must be put to params everywhere where it is modified.
- Matrix changes needn't be tracked in the algorithms any more.
- CPU debayering must watch for changes of the corresponding parameters
  to update the lookup tables when and only when needed.
- Swapping red and blue is integrated into lookup table constructions.
- gpuIspEnabled flags are removed as they are not needed any more.

Reviewed-by: Robert Mader <robert.mader@collabora.com>
Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
Acked-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
This commit is contained in:
Milan Zamazal
2026-01-28 12:44:01 +01:00
committed by Kieran Bingham
parent c43aeaade0
commit 3ffaa4c0e2
18 changed files with 188 additions and 478 deletions
Download Patch File Download Diff File Expand all files Collapse all files

172
src/libcamera/software_isp/debayer.cpp
View File

@@ -1,7 +1,7 @@
/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2023, Linaro Ltd
* Copyright (C) 2023-2025 Red Hat Inc.
* Copyright (C) 2023-2026 Red Hat Inc.
*
* Authors:
* Hans de Goede <hdegoede@redhat.com>
@@ -25,99 +25,28 @@ namespace libcamera {
*/
/**
* \var DebayerParams::kRGBLookupSize
* \brief Size of a color lookup table
* \var DebayerParams::gains
* \brief Colour channel gains
*/
/**
* \struct DebayerParams::CcmColumn
* \brief Type of a single column of a color correction matrix (CCM)
*
* When multiplying an input pixel, columns in the CCM correspond to the red,
* green or blue component of input pixel values, while rows correspond to the
* red, green or blue components of the output pixel values. The members of the
* CcmColumn structure are named after the colour components of the output pixel
* values they correspond to.
*/
/**
* \var DebayerParams::CcmColumn::r
* \brief Red (first) component of a CCM column
*/
/**
* \var DebayerParams::CcmColumn::g
* \brief Green (second) component of a CCM column
*/
/**
* \var DebayerParams::CcmColumn::b
* \brief Blue (third) component of a CCM column
*/
/**
* \typedef DebayerParams::LookupTable
* \brief Type of the lookup tables for single lookup values
*/
/**
* \typedef DebayerParams::CcmLookupTable
* \brief Type of the CCM lookup tables for red, green, blue values
*/
/**
* \var DebayerParams::red
* \brief Lookup table for red color, mapping input values to output values
*/
/**
* \var DebayerParams::green
* \brief Lookup table for green color, mapping input values to output values
*/
/**
* \var DebayerParams::blue
* \brief Lookup table for blue color, mapping input values to output values
*/
/**
* \var DebayerParams::redCcm
* \brief Lookup table for the CCM red column, mapping input values to output values
*/
/**
* \var DebayerParams::greenCcm
* \brief Lookup table for the CCM green column, mapping input values to output values
*/
/**
* \var DebayerParams::blueCcm
* \brief Lookup table for the CCM blue column, mapping input values to output values
*/
/**
* \var DebayerParams::gammaLut
* \brief Gamma lookup table used with color correction matrix
*/
/**
* \var DebayerParams::ccm
* \brief Per frame colour correction matrix for GPUISP
* \var DebayerParams::combinedMatrix
* \brief Colour correction matrix, including other adjustments
*/
/**
* \var DebayerParams::blackLevel
* \brief Blacklevel gains for the GPUISP
* \brief Black level values
*/
/**
* \var DebayerParams::gamma
* \brief Gamma value for the GPUISP
* \brief Gamma value, e.g. 1/2.2
*/
/**
* \var DebayerParams::contrastExp
* \brief Contrast value for GPUISP
* \brief Contrast value to be used as an exponent
*/
/**
@@ -131,13 +60,6 @@ LOG_DEFINE_CATEGORY(Debayer)
Debayer::Debayer(const GlobalConfiguration &configuration) : bench_(configuration)
{
/* Initialize color lookup tables */
for (unsigned int i = 0; i < DebayerParams::kRGBLookupSize; i++) {
red_[i] = green_[i] = blue_[i] = i;
redCcm_[i] = { static_cast<int16_t>(i), 0, 0 };
greenCcm_[i] = { 0, static_cast<int16_t>(i), 0 };
blueCcm_[i] = { 0, 0, static_cast<int16_t>(i) };
}
}
Debayer::~Debayer()
@@ -305,56 +227,6 @@ Debayer::~Debayer()
* \brief Output size object
*/
/**
* \var Debayer::red_
* \brief Lookup table for red channel gain and correction values
*
* This table provides precomputed per-pixel or per-intensity
* correction values for the red color channel used during debayering.
*/
/**
* \var Debayer::green_
* \brief Lookup table for green channel gain and correction values
*
* This table provides precomputed per-pixel or per-intensity
* correction values for the green color channel used during debayering.
*/
/**
* \var Debayer::blue_
* \brief Lookup table for blue channel gain and correction values
*
* This table provides precomputed per-pixel or per-intensity
* correction values for the blue color channel used during debayering.
*/
/**
* \var Debayer::redCcm_
* \brief Red channel Color Correction Matrix (CCM) lookup table
*
* Contains coefficients for green channel color correction.
*/
/**
* \var Debayer::greenCcm_
* \brief Green channel Color Correction Matrix (CCM) lookup table
*
* Contains coefficients for green channel color correction.
*/
/**
* \var Debayer::blueCcm_
* \brief Blue channel Color Correction Matrix (CCM) lookup table
*
* Contains coefficients for blue channel color correction.
*/
/**
* \var Debayer::gammaLut_
* \brief Gamma correction lookup table
*/
/**
* \var Debayer::swapRedBlueGains_
* \brief Flag indicating whether red and blue channel gains should be swapped
@@ -396,34 +268,6 @@ Debayer::~Debayer()
* DebayerEGL::start.
*/
/**
* \fn void Debayer::setParams(DebayerParams &params)
* \brief Select the bayer params to use for the next frame debayer
* \param[in] params The parameters to be used in debayering
*/
void Debayer::setParams(DebayerParams &params)
{
green_ = params.green;
greenCcm_ = params.greenCcm;
if (swapRedBlueGains_) {
red_ = params.blue;
blue_ = params.red;
redCcm_ = params.blueCcm;
blueCcm_ = params.redCcm;
for (unsigned int i = 0; i < 256; i++) {
std::swap(redCcm_[i].r, redCcm_[i].b);
std::swap(greenCcm_[i].r, greenCcm_[i].b);
std::swap(blueCcm_[i].r, blueCcm_[i].b);
}
} else {
red_ = params.red;
blue_ = params.blue;
redCcm_ = params.redCcm;
blueCcm_ = params.blueCcm;
}
gammaLut_ = params.gammaLut;
}
/**
* \fn void Debayer::dmaSyncBegin(DebayerParams &params)
* \brief Common CPU/GPU Dma Sync Buffer begin

8
src/libcamera/software_isp/debayer.h
View File

@@ -78,13 +78,6 @@ public:
Size outputSize_;
PixelFormat inputPixelFormat_;
PixelFormat outputPixelFormat_;
DebayerParams::LookupTable red_;
DebayerParams::LookupTable green_;
DebayerParams::LookupTable blue_;
DebayerParams::CcmLookupTable redCcm_;
DebayerParams::CcmLookupTable greenCcm_;
DebayerParams::CcmLookupTable blueCcm_;
DebayerParams::LookupTable gammaLut_;
bool swapRedBlueGains_;
Benchmark bench_;
@@ -92,7 +85,6 @@ private:
virtual Size patternSize(PixelFormat inputFormat) = 0;
protected:
void setParams(DebayerParams &params);
void dmaSyncBegin(std::vector<DmaSyncer> &dmaSyncers, FrameBuffer *input, FrameBuffer *output);
static bool isStandardBayerOrder(BayerFormat::Order order);
};

136
src/libcamera/software_isp/debayer_cpu.cpp
View File

@@ -1,7 +1,7 @@
/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2023, Linaro Ltd
* Copyright (C) 2023-2025 Red Hat Inc.
* Copyright (C) 2023-2026 Red Hat Inc.
*
* Authors:
* Hans de Goede <hdegoede@redhat.com>
@@ -68,21 +68,21 @@ DebayerCpu::~DebayerCpu() = default;
#define GAMMA(value) \
*dst++ = gammaLut_[std::clamp(value, 0, static_cast<int>(gammaLut_.size()) - 1)]
#define STORE_PIXEL(b_, g_, r_) \
if constexpr (ccmEnabled) { \
const DebayerParams::CcmColumn &blue = blueCcm_[b_]; \
const DebayerParams::CcmColumn &green = greenCcm_[g_]; \
const DebayerParams::CcmColumn &red = redCcm_[r_]; \
GAMMA(blue.b + green.b + red.b); \
GAMMA(blue.g + green.g + red.g); \
GAMMA(blue.r + green.r + red.r); \
} else { \
*dst++ = blue_[b_]; \
*dst++ = green_[g_]; \
*dst++ = red_[r_]; \
} \
if constexpr (addAlphaByte) \
*dst++ = 255; \
#define STORE_PIXEL(b_, g_, r_) \
if constexpr (ccmEnabled) { \
const CcmColumn &blue = blueCcm_[b_]; \
const CcmColumn &green = greenCcm_[g_]; \
const CcmColumn &red = redCcm_[r_]; \
GAMMA(blue.b + green.b + red.b); \
GAMMA(blue.g + green.g + red.g); \
GAMMA(blue.r + green.r + red.r); \
} else { \
*dst++ = blue_[b_]; \
*dst++ = green_[g_]; \
*dst++ = red_[r_]; \
} \
if constexpr (addAlphaByte) \
*dst++ = 255; \
x++;
/*
@@ -525,6 +525,16 @@ int DebayerCpu::configure(const StreamConfiguration &inputCfg,
if (ret != 0)
return -EINVAL;
ccmEnabled_ = ccmEnabled;
/*
* Lookup tables must be initialized because the initial value is used for
* the first two frames, i.e. until stats processing starts providing its
* own parameters. Let's enforce recomputing lookup tables by setting the
* stored last used gamma to an out-of-range value.
*/
params_.gamma = 1.0;
window_.x = ((inputCfg.size.width - outputCfg.size.width) / 2) &
~(inputConfig_.patternSize.width - 1);
window_.y = ((inputCfg.size.height - outputCfg.size.height) / 2) &
@@ -740,6 +750,98 @@ void DebayerCpu::process4(uint32_t frame, const uint8_t *src, uint8_t *dst)
}
}
void DebayerCpu::updateGammaTable(DebayerParams &params)
{
const RGB<float> blackLevel = params.blackLevel;
/* Take let's say the green channel black level */
const unsigned int blackIndex = blackLevel[1] * gammaTable_.size();
const float gamma = params.gamma;
const float contrastExp = params.contrastExp;
const float divisor = gammaTable_.size() - blackIndex - 1.0;
for (unsigned int i = blackIndex; i < gammaTable_.size(); i++) {
float normalized = (i - blackIndex) / divisor;
/* Convert 0..2 to 0..infinity; avoid actual inifinity at tan(pi/2) */
/* Apply simple S-curve */
if (normalized < 0.5)
normalized = 0.5 * std::pow(normalized / 0.5, contrastExp);
else
normalized = 1.0 - 0.5 * std::pow((1.0 - normalized) / 0.5, contrastExp);
gammaTable_[i] = UINT8_MAX *
std::pow(normalized, gamma);
}
/*
* Due to CCM operations, the table lookup may reach indices below the black
* level. Let's set the table values below black level to the minimum
* non-black value to prevent problems when the minimum value is
* significantly non-zero (for example, when the image should be all grey).
*/
std::fill(gammaTable_.begin(), gammaTable_.begin() + blackIndex,
gammaTable_[blackIndex]);
}
void DebayerCpu::updateLookupTables(DebayerParams &params)
{
const bool gammaUpdateNeeded =
params.gamma != params_.gamma ||
params.blackLevel != params_.blackLevel ||
params.contrastExp != params_.contrastExp;
if (gammaUpdateNeeded)
updateGammaTable(params);
auto matrixChanged = [](const Matrix<float, 3, 3> &m1, const Matrix<float, 3, 3> &m2) -> bool {
return !std::equal(m1.data().begin(), m1.data().end(), m2.data().begin());
};
const unsigned int gammaTableSize = gammaTable_.size();
const double div = static_cast<double>(kRGBLookupSize) / gammaTableSize;
if (ccmEnabled_) {
if (gammaUpdateNeeded ||
matrixChanged(params.combinedMatrix, params_.combinedMatrix)) {
auto &red = swapRedBlueGains_ ? blueCcm_ : redCcm_;
auto &green = greenCcm_;
auto &blue = swapRedBlueGains_ ? redCcm_ : blueCcm_;
const unsigned int redIndex = swapRedBlueGains_ ? 2 : 0;
const unsigned int greenIndex = 1;
const unsigned int blueIndex = swapRedBlueGains_ ? 0 : 2;
for (unsigned int i = 0; i < kRGBLookupSize; i++) {
red[i].r = std::round(i * params.combinedMatrix[redIndex][0]);
red[i].g = std::round(i * params.combinedMatrix[greenIndex][0]);
red[i].b = std::round(i * params.combinedMatrix[blueIndex][0]);
green[i].r = std::round(i * params.combinedMatrix[redIndex][1]);
green[i].g = std::round(i * params.combinedMatrix[greenIndex][1]);
green[i].b = std::round(i * params.combinedMatrix[blueIndex][1]);
blue[i].r = std::round(i * params.combinedMatrix[redIndex][2]);
blue[i].g = std::round(i * params.combinedMatrix[greenIndex][2]);
blue[i].b = std::round(i * params.combinedMatrix[blueIndex][2]);
gammaLut_[i] = gammaTable_[i / div];
}
}
} else {
if (gammaUpdateNeeded || params.gains != params_.gains) {
auto &gains = params.gains;
auto &red = swapRedBlueGains_ ? blue_ : red_;
auto &green = green_;
auto &blue = swapRedBlueGains_ ? red_ : blue_;
for (unsigned int i = 0; i < kRGBLookupSize; i++) {
/* Apply gamma after gain! */
const RGB<float> lutGains = (gains * i / div).min(gammaTableSize - 1);
red[i] = gammaTable_[static_cast<unsigned int>(lutGains.r())];
green[i] = gammaTable_[static_cast<unsigned int>(lutGains.g())];
blue[i] = gammaTable_[static_cast<unsigned int>(lutGains.b())];
}
}
}
LOG(Debayer, Debug)
<< "Debayer parameters: blackLevel=" << params.blackLevel
<< "; gamma=" << params.gamma
<< "; contrastExp=" << params.contrastExp
<< "; gains=" << params.gains
<< "; matrix=" << params.combinedMatrix;
params_ = params;
}
void DebayerCpu::process(uint32_t frame, FrameBuffer *input, FrameBuffer *output, DebayerParams params)
{
bench_.startFrame();
@@ -748,7 +850,7 @@ void DebayerCpu::process(uint32_t frame, FrameBuffer *input, FrameBuffer *output
dmaSyncBegin(dmaSyncers, input, output);
setParams(params);
updateLookupTables(params);
/* Copy metadata from the input buffer */
FrameMetadata &metadata = output->_d()->metadata();

26
src/libcamera/software_isp/debayer_cpu.h
View File

@@ -1,7 +1,7 @@
/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2023, Linaro Ltd
* Copyright (C) 2023-2025 Red Hat Inc.
* Copyright (C) 2023-2026 Red Hat Inc.
*
* Authors:
* Hans de Goede <hdegoede@redhat.com>
@@ -18,6 +18,8 @@
#include <libcamera/base/object.h>
#include "libcamera/internal/bayer_format.h"
#include "libcamera/internal/global_configuration.h"
#include "libcamera/internal/software_isp/debayer_params.h"
#include "libcamera/internal/software_isp/swstats_cpu.h"
#include "debayer.h"
@@ -108,10 +110,32 @@ private:
void memcpyNextLine(const uint8_t *linePointers[]);
void process2(uint32_t frame, const uint8_t *src, uint8_t *dst);
void process4(uint32_t frame, const uint8_t *src, uint8_t *dst);
void updateGammaTable(DebayerParams &params);
void updateLookupTables(DebayerParams &params);
/* Max. supported Bayer pattern height is 4, debayering this requires 5 lines */
static constexpr unsigned int kMaxLineBuffers = 5;
static constexpr unsigned int kRGBLookupSize = 256;
static constexpr unsigned int kGammaLookupSize = 1024;
struct CcmColumn {
int16_t r;
int16_t g;
int16_t b;
};
using LookupTable = std::array<uint8_t, kRGBLookupSize>;
using CcmLookupTable = std::array<CcmColumn, kRGBLookupSize>;
LookupTable red_;
LookupTable green_;
LookupTable blue_;
CcmLookupTable redCcm_;
CcmLookupTable greenCcm_;
CcmLookupTable blueCcm_;
std::array<double, kGammaLookupSize> gammaTable_;
LookupTable gammaLut_;
bool ccmEnabled_;
DebayerParams params_;
debayerFn debayer0_;
debayerFn debayer1_;
debayerFn debayer2_;

22
src/libcamera/software_isp/debayer_egl.cpp
View File

@@ -475,18 +475,18 @@ void DebayerEGL::setShaderVariableValues(DebayerParams &params)
<< " textureUniformProjMatrix_ " << textureUniformProjMatrix_;
GLfloat ccm[9] = {
params.ccm[0][0],
params.ccm[0][1],
params.ccm[0][2],
params.ccm[1][0],
params.ccm[1][1],
params.ccm[1][2],
params.ccm[2][0],
params.ccm[2][1],
params.ccm[2][2],
params.combinedMatrix[0][0],
params.combinedMatrix[0][1],
params.combinedMatrix[0][2],
params.combinedMatrix[1][0],
params.combinedMatrix[1][1],
params.combinedMatrix[1][2],
params.combinedMatrix[2][0],
params.combinedMatrix[2][1],
params.combinedMatrix[2][2],
};
glUniformMatrix3fv(ccmUniformDataIn_, 1, GL_FALSE, ccm);
LOG(Debayer, Debug) << " ccmUniformDataIn_ " << ccmUniformDataIn_ << " data " << params.ccm;
LOG(Debayer, Debug) << " ccmUniformDataIn_ " << ccmUniformDataIn_ << " data " << params.combinedMatrix;
/*
* 0 = Red, 1 = Green, 2 = Blue
@@ -544,8 +544,6 @@ void DebayerEGL::process(uint32_t frame, FrameBuffer *input, FrameBuffer *output
dmaSyncBegin(dmaSyncers, input, nullptr);
setParams(params);
/* Copy metadata from the input buffer */
FrameMetadata &metadata = output->_d()->metadata();
metadata.status = input->metadata().status;

29
src/libcamera/software_isp/software_isp.cpp
View File

@@ -84,23 +84,6 @@ SoftwareIsp::SoftwareIsp(PipelineHandler *pipe, const CameraSensor *sensor,
DmaBufAllocator::DmaBufAllocatorFlag::SystemHeap |
DmaBufAllocator::DmaBufAllocatorFlag::UDmaBuf)
{
/*
* debayerParams_ must be initialized because the initial value is used for
* the first two frames, i.e. until stats processing starts providing its
* own parameters.
*
* \todo This should be handled in the same place as the related
* operations, in the IPA module.
*/
std::array<uint8_t, 256> gammaTable;
for (unsigned int i = 0; i < 256; i++)
gammaTable[i] = UINT8_MAX * std::pow(i / 256.0, 0.5);
for (unsigned int i = 0; i < DebayerParams::kRGBLookupSize; i++) {
debayerParams_.red[i] = gammaTable[i];
debayerParams_.green[i] = gammaTable[i];
debayerParams_.blue[i] = gammaTable[i];
}
if (!dmaHeap_.isValid()) {
LOG(SoftwareIsp, Error) << "Failed to create DmaBufAllocator object";
return;
@@ -121,8 +104,6 @@ SoftwareIsp::SoftwareIsp(PipelineHandler *pipe, const CameraSensor *sensor,
}
stats->statsReady.connect(this, &SoftwareIsp::statsReady);
bool gpuIspEnabled;
#if HAVE_DEBAYER_EGL
std::optional<std::string> softISPMode = configuration.envOption("LIBCAMERA_SOFTISP_MODE", { "software_isp", "mode" });
if (softISPMode) {
@@ -133,15 +114,12 @@ SoftwareIsp::SoftwareIsp(PipelineHandler *pipe, const CameraSensor *sensor,
}
}
if (!softISPMode || softISPMode == "gpu") {
if (!softISPMode || softISPMode == "gpu")
debayer_ = std::make_unique<DebayerEGL>(std::move(stats), configuration);
gpuIspEnabled = true;
}
#endif
if (!debayer_) {
if (!debayer_)
debayer_ = std::make_unique<DebayerCpu>(std::move(stats), configuration);
gpuIspEnabled = false;
}
debayer_->inputBufferReady.connect(this, &SoftwareIsp::inputReady);
debayer_->outputBufferReady.connect(this, &SoftwareIsp::outputReady);
@@ -173,7 +151,6 @@ SoftwareIsp::SoftwareIsp(PipelineHandler *pipe, const CameraSensor *sensor,
sharedParams_.fd(),
sensorInfo,
sensor->controls(),
gpuIspEnabled,
ipaControls,
&ccmEnabled_);
if (ret) {