[libcamera-devel] [PATCH v3.2 5/5] ipa: rkisp1: Introduce AWB
Laurent Pinchart
laurent.pinchart at ideasonboard.com
Sun Mar 27 22:43:29 CEST 2022
Hi Jnea-Michel,
Thank you for the patch.
On Thu, Feb 24, 2022 at 03:39:50PM +0100, Jean-Michel Hautbois wrote:
> The RkISP1 ISP calculates a mean value for Y, Cr and Cb at each frame.
> There is a RGB mode which could theoretically give us the values for R,
> G and B directly, but it seems to be failing right now.
>
> Convert those values into R, G and B and estimate the gain to apply in a
> grey world.
>
> Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois at ideasonboard.com>
> Tested-by: Peter Griffin <peter.griffin at linaro.org>
>
> ---
> v3.2: - Change the clamping for the awb gains
> v3: - Change the date of the copyright
> - Fix the YCbCr to RGB formula
> ---
> src/ipa/rkisp1/algorithms/awb.cpp | 179 ++++++++++++++++++++++++++
> src/ipa/rkisp1/algorithms/awb.h | 33 +++++
> src/ipa/rkisp1/algorithms/meson.build | 1 +
> src/ipa/rkisp1/ipa_context.cpp | 28 ++++
> src/ipa/rkisp1/ipa_context.h | 16 +++
> src/ipa/rkisp1/rkisp1.cpp | 2 +
> 6 files changed, 259 insertions(+)
> create mode 100644 src/ipa/rkisp1/algorithms/awb.cpp
> create mode 100644 src/ipa/rkisp1/algorithms/awb.h
>
> diff --git a/src/ipa/rkisp1/algorithms/awb.cpp b/src/ipa/rkisp1/algorithms/awb.cpp
> new file mode 100644
> index 00000000..a34fac2a
> --- /dev/null
> +++ b/src/ipa/rkisp1/algorithms/awb.cpp
> @@ -0,0 +1,179 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2021-2022, Ideas On Board
> + *
> + * awb.cpp - AWB control algorithm
> + */
> +
> +#include "awb.h"
> +
> +#include <algorithm>
> +#include <cmath>
> +
> +#include <libcamera/base/log.h>
> +
> +#include <libcamera/ipa/core_ipa_interface.h>
> +
> +/**
> + * \file awb.h
> + */
> +
> +namespace libcamera {
> +
> +namespace ipa::rkisp1::algorithms {
> +
> +/**
> + * \class Awb
> + * \brief A Grey world white balance correction algorithm
> + */
> +
> +LOG_DEFINE_CATEGORY(RkISP1Awb)
> +
> +/**
> + * \copydoc libcamera::ipa::Algorithm::configure
> + */
> +int Awb::configure(IPAContext &context,
> + const IPACameraSensorInfo &configInfo)
> +{
> + context.frameContext.awb.gains.red = 1.0;
> + context.frameContext.awb.gains.blue = 1.0;
> + context.frameContext.awb.gains.green = 1.0;
> +
> + /*
> + * Define the measurement window for AWB as a centered rectangle
> + * covering 3/4 of the image width and height.
> + */
> + context.configuration.awb.measureWindow.h_offs = configInfo.outputSize.width / 8;
> + context.configuration.awb.measureWindow.v_offs = configInfo.outputSize.height / 8;
> + context.configuration.awb.measureWindow.h_size = 3 * configInfo.outputSize.width / 4;
> + context.configuration.awb.measureWindow.v_size = 3 * configInfo.outputSize.height / 4;
> +
> + return 0;
> +}
> +
> +uint32_t Awb::estimateCCT(double red, double green, double blue)
> +{
> + /* Convert the RGB values to CIE tristimulus values (XYZ) */
> + double X = (-0.14282) * (red) + (1.54924) * (green) + (-0.95641) * (blue);
> + double Y = (-0.32466) * (red) + (1.57837) * (green) + (-0.73191) * (blue);
> + double Z = (-0.68202) * (red) + (0.77073) * (green) + (0.56332) * (blue);
> +
> + /* Calculate the normalized chromaticity values */
> + double x = X / (X + Y + Z);
> + double y = Y / (X + Y + Z);
> +
> + /* Calculate CCT */
> + double n = (x - 0.3320) / (0.1858 - y);
> + return 449 * n * n * n + 3525 * n * n + 6823.3 * n + 5520.33;
> +}
> +
> +/**
> + * \copydoc libcamera::ipa::Algorithm::prepare
> + */
> +void Awb::prepare(IPAContext &context, rkisp1_params_cfg *params)
> +{
> + params->others.awb_gain_config.gain_green_b = 256 * context.frameContext.awb.gains.green;
> + params->others.awb_gain_config.gain_blue = 256 * context.frameContext.awb.gains.blue;
> + params->others.awb_gain_config.gain_red = 256 * context.frameContext.awb.gains.red;
> + params->others.awb_gain_config.gain_green_r = 256 * context.frameContext.awb.gains.green;
> +
> + /* Update the gains. */
> + params->module_cfg_update |= RKISP1_CIF_ISP_MODULE_AWB_GAIN;
> +
> + /* If we already have configured the gains and window, return. */
> + if (context.frameContext.frameCount > 0)
> + return;
> +
> + /* Configure the gains to apply. */
> + params->module_en_update |= RKISP1_CIF_ISP_MODULE_AWB_GAIN;
> + /* Update the ISP to apply the gains configured. */
> + params->module_ens |= RKISP1_CIF_ISP_MODULE_AWB_GAIN;
> +
> + /* Configure the measure window for AWB. */
> + params->meas.awb_meas_config.awb_wnd = context.configuration.awb.measureWindow;
> + /*
> + * Measure Y, Cr and Cb means.
> + * \todo RGB is not working, the kernel seems to not configure it ?
> + */
> + params->meas.awb_meas_config.awb_mode = RKISP1_CIF_ISP_AWB_MODE_YCBCR;
> + /* Reference Cr and Cb. */
> + params->meas.awb_meas_config.awb_ref_cb = 128;
> + params->meas.awb_meas_config.awb_ref_cr = 128;
> + /* Y values to include are between min_y and max_y only. */
> + params->meas.awb_meas_config.min_y = 16;
> + params->meas.awb_meas_config.max_y = 250;
> + /* Maximum Cr+Cb value to take into account for awb. */
> + params->meas.awb_meas_config.max_csum = 250;
> + /* Minimum Cr and Cb values to take into account. */
> + params->meas.awb_meas_config.min_c = 16;
> + /* Number of frames to use to estimate the mean (0 means 1 frame). */
> + params->meas.awb_meas_config.frames = 0;
> +
> + /* Update AWB measurement unit configuration. */
> + params->module_cfg_update |= RKISP1_CIF_ISP_MODULE_AWB;
> + /* Make sure the ISP is measuring the means for the next frame. */
> + params->module_en_update |= RKISP1_CIF_ISP_MODULE_AWB;
> + params->module_ens |= RKISP1_CIF_ISP_MODULE_AWB;
> +}
> +
> +/**
> + * \copydoc libcamera::ipa::Algorithm::process
> + */
> +void Awb::process([[maybe_unused]] IPAContext &context, const rkisp1_stat_buffer *stats)
> +{
> + const rkisp1_cif_isp_stat *params = &stats->params;
> + const rkisp1_cif_isp_awb_stat *awb = ¶ms->awb;
> +
> + /* Get the YCbCr mean values */
> + double yMean = awb->awb_mean[0].mean_y_or_g;
> + double crMean = awb->awb_mean[0].mean_cr_or_r;
> + double cbMean = awb->awb_mean[0].mean_cb_or_b;
> +
> + /*
> + * Convert from YCbCr to RGB.
> + * The hardware uses the following formulas:
> + * Y = 16 + 0.2500 R + 0.5000 G + 0.1094 B
> + * Cb = 128 - 0.1406 R - 0.2969 G + 0.4375 B
> + * Cr = 128 + 0.4375 R - 0.3750 G - 0.0625 B
> + *
> + * The inverse matrix is thus:
> + * [[1,1636, -0,0623, 1,6008]
> + * [1,1636, -0,4045, -0,7949]
> + * [1,1636, 1,9912, -0,0250]]
> + */
> + yMean -= 16;
> + cbMean -= 128;
> + crMean -= 128;
> + double redMean = 1.1636 * yMean - 0.0623 * cbMean + 1.6008 * crMean;
> + double blueMean = 1.1636 * yMean - 0.4045 * cbMean - 0.7949 * crMean;
> + double greenMean = 1.1636 * yMean + 1.9912 * cbMean - 0.0250 * crMean;
You've swapped blue and green.
> +
> + /* Estimate the red and blue gains to apply in a grey world. */
> + double redGain = greenMean / (redMean + 1);
> + double blueGain = greenMean / (blueMean + 1);
> +
> + /*
> + * Gain values are unsigned integer value, range 0 to 4 with 8 bit
> + * fractional part.
> + */
> + redGain = std::clamp(redGain, 0.0, 1023.0 / 256);
> + blueGain = std::clamp(blueGain, 0.0, 1023.0 / 256);
Shouldn't you saturate after filtering, not before, to avoid possibly
slowing down convergence ? That's probably a theoretical concern though,
as we shouldn't reach saturation.
Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> +
> + /* Filter the values to avoid oscillations. */
> + IPAFrameContext &frameContext = context.frameContext;
> +
> + frameContext.awb.temperatureK = estimateCCT(redMean, greenMean, blueMean);
> + frameContext.awb.gains.red = 0.2 * redGain +
> + 0.8 * frameContext.awb.gains.red;
> + frameContext.awb.gains.blue = 0.2 * blueGain +
> + 0.8 * frameContext.awb.gains.blue;
> + /* Hardcode the green gain to 1.0. */
> + frameContext.awb.gains.green = 1.0;
> +
> + LOG(RkISP1Awb, Debug) << "Gain found for red: " << context.frameContext.awb.gains.red
> + << " and for blue: " << context.frameContext.awb.gains.blue;
> +}
> +
> +} /* namespace ipa::rkisp1::algorithms */
> +
> +} /* namespace libcamera */
> diff --git a/src/ipa/rkisp1/algorithms/awb.h b/src/ipa/rkisp1/algorithms/awb.h
> new file mode 100644
> index 00000000..11946643
> --- /dev/null
> +++ b/src/ipa/rkisp1/algorithms/awb.h
> @@ -0,0 +1,33 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2021-2022, Ideas On Board
> + *
> + * awb.h - AWB control algorithm
> + */
> +
> +#pragma once
> +
> +#include <linux/rkisp1-config.h>
> +
> +#include "algorithm.h"
> +
> +namespace libcamera {
> +
> +namespace ipa::rkisp1::algorithms {
> +
> +class Awb : public Algorithm
> +{
> +public:
> + Awb() = default;
> + ~Awb() = default;
> +
> + int configure(IPAContext &context, const IPACameraSensorInfo &configInfo) override;
> + void prepare(IPAContext &context, rkisp1_params_cfg *params) override;
> + void process(IPAContext &context, const rkisp1_stat_buffer *stats) override;
> +
> +private:
> + uint32_t estimateCCT(double red, double green, double blue);
> +};
> +
> +} /* namespace ipa::rkisp1::algorithms */
> +} /* namespace libcamera */
> diff --git a/src/ipa/rkisp1/algorithms/meson.build b/src/ipa/rkisp1/algorithms/meson.build
> index 27c97731..7ec53d89 100644
> --- a/src/ipa/rkisp1/algorithms/meson.build
> +++ b/src/ipa/rkisp1/algorithms/meson.build
> @@ -2,5 +2,6 @@
>
> rkisp1_ipa_algorithms = files([
> 'agc.cpp',
> + 'awb.cpp',
> 'blc.cpp',
> ])
> diff --git a/src/ipa/rkisp1/ipa_context.cpp b/src/ipa/rkisp1/ipa_context.cpp
> index 790e159b..d6d8456c 100644
> --- a/src/ipa/rkisp1/ipa_context.cpp
> +++ b/src/ipa/rkisp1/ipa_context.cpp
> @@ -81,6 +81,14 @@ namespace libcamera::ipa::rkisp1 {
> * \brief Hardware revision of the ISP
> */
>
> +/**
> + * \var IPASessionConfiguration::awb
> + * \brief AWB parameters configuration of the IPA
> + *
> + * \var IPASessionConfiguration::awb.measureWindow
> + * \brief AWB measure window
> + */
> +
> /**
> * \var IPASessionConfiguration::sensor
> * \brief Sensor-specific configuration of the IPA
> @@ -105,6 +113,26 @@ namespace libcamera::ipa::rkisp1 {
> * The gain should be adapted to the sensor specific gain code before applying.
> */
>
> +/**
> + * \var IPAFrameContext::awb
> + * \brief Context for the Automatic White Balance algorithm
> + *
> + * \struct IPAFrameContext::awb.gains
> + * \brief White balance gains
> + *
> + * \var IPAFrameContext::awb.gains.red
> + * \brief White balance gain for R channel
> + *
> + * \var IPAFrameContext::awb.gains.green
> + * \brief White balance gain for G channel
> + *
> + * \var IPAFrameContext::awb.gains.blue
> + * \brief White balance gain for B channel
> + *
> + * \var IPAFrameContext::awb.temperatureK
> + * \brief Estimated color temperature
> + */
> +
> /**
> * \var IPAFrameContext::sensor
> * \brief Effective sensor values
> diff --git a/src/ipa/rkisp1/ipa_context.h b/src/ipa/rkisp1/ipa_context.h
> index 35e9b8e5..f387cace 100644
> --- a/src/ipa/rkisp1/ipa_context.h
> +++ b/src/ipa/rkisp1/ipa_context.h
> @@ -12,6 +12,8 @@
>
> #include <libcamera/base/utils.h>
>
> +#include <libcamera/geometry.h>
> +
> namespace libcamera {
>
> namespace ipa::rkisp1 {
> @@ -25,6 +27,10 @@ struct IPASessionConfiguration {
> struct rkisp1_cif_isp_window measureWindow;
> } agc;
>
> + struct {
> + struct rkisp1_cif_isp_window measureWindow;
> + } awb;
> +
> struct {
> utils::Duration lineDuration;
> } sensor;
> @@ -40,6 +46,16 @@ struct IPAFrameContext {
> double gain;
> } agc;
>
> + struct {
> + struct {
> + double red;
> + double green;
> + double blue;
> + } gains;
> +
> + double temperatureK;
> + } awb;
> +
> struct {
> uint32_t exposure;
> double gain;
> diff --git a/src/ipa/rkisp1/rkisp1.cpp b/src/ipa/rkisp1/rkisp1.cpp
> index bb3deb93..f4db3a21 100644
> --- a/src/ipa/rkisp1/rkisp1.cpp
> +++ b/src/ipa/rkisp1/rkisp1.cpp
> @@ -27,6 +27,7 @@
>
> #include "algorithms/agc.h"
> #include "algorithms/algorithm.h"
> +#include "algorithms/awb.h"
> #include "algorithms/blc.h"
> #include "libipa/camera_sensor_helper.h"
>
> @@ -127,6 +128,7 @@ int IPARkISP1::init(const IPASettings &settings, unsigned int hwRevision)
>
> /* Construct our Algorithms */
> algorithms_.push_back(std::make_unique<algorithms::Agc>());
> + algorithms_.push_back(std::make_unique<algorithms::Awb>());
> algorithms_.push_back(std::make_unique<algorithms::BlackLevelCorrection>());
>
> return 0;
> --
> 2.32.0
>
--
Regards,
Laurent Pinchart
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