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/* 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 <iomanip>
#include <libcamera/base/log.h>
#include <libcamera/control_ids.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)
Awb::Awb()
: rgbMode_(false)
{
}
/**
* \copydoc libcamera::ipa::Algorithm::configure
*/
int Awb::configure(IPAContext &context,
const IPACameraSensorInfo &configInfo)
{
context.activeState.awb.gains.manual.red = 1.0;
context.activeState.awb.gains.manual.blue = 1.0;
context.activeState.awb.gains.manual.green = 1.0;
context.activeState.awb.gains.automatic.red = 1.0;
context.activeState.awb.gains.automatic.blue = 1.0;
context.activeState.awb.gains.automatic.green = 1.0;
context.activeState.awb.autoEnabled = true;
/*
* 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;
context.configuration.awb.enabled = true;
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, const uint32_t frame,
IPAFrameContext &frameContext, rkisp1_params_cfg *params)
{
/*
* This is the latest time we can read the active state. This is the
* most up-to-date automatic values we can read.
*/
if (frameContext.awb.autoEnabled) {
frameContext.awb.gains.red = context.activeState.awb.gains.automatic.red;
frameContext.awb.gains.green = context.activeState.awb.gains.automatic.green;
frameContext.awb.gains.blue = context.activeState.awb.gains.automatic.blue;
}
params->others.awb_gain_config.gain_green_b = 256 * frameContext.awb.gains.green;
params->others.awb_gain_config.gain_blue = 256 * frameContext.awb.gains.blue;
params->others.awb_gain_config.gain_red = 256 * frameContext.awb.gains.red;
params->others.awb_gain_config.gain_green_r = 256 * frameContext.awb.gains.green;
/* Update the gains. */
params->module_cfg_update |= RKISP1_CIF_ISP_MODULE_AWB_GAIN;
/* If we have already set the AWB measurement parameters, return. */
if (frame > 0)
return;
rkisp1_cif_isp_awb_meas_config &awb_config = params->meas.awb_meas_config;
/* Configure the measure window for AWB. */
awb_config.awb_wnd = context.configuration.awb.measureWindow;
/* Number of frames to use to estimate the means (0 means 1 frame). */
awb_config.frames = 0;
/* Select RGB or YCbCr means measurement. */
if (rgbMode_) {
awb_config.awb_mode = RKISP1_CIF_ISP_AWB_MODE_RGB;
/*
* For RGB-based measurements, pixels are selected with maximum
* red, green and blue thresholds that are set in the
* awb_ref_cr, awb_min_y and awb_ref_cb respectively. The other
* values are not used, set them to 0.
*/
awb_config.awb_ref_cr = 250;
awb_config.min_y = 250;
awb_config.awb_ref_cb = 250;
awb_config.max_y = 0;
awb_config.min_c = 0;
awb_config.max_csum = 0;
} else {
awb_config.awb_mode = RKISP1_CIF_ISP_AWB_MODE_YCBCR;
/* Set the reference Cr and Cb (AWB target) to white. */
awb_config.awb_ref_cb = 128;
awb_config.awb_ref_cr = 128;
/*
* Filter out pixels based on luminance and chrominance values.
* The acceptable luma values are specified as a [16, 250]
* range, while the acceptable chroma values are specified with
* a minimum of 16 and a maximum Cb+Cr sum of 250.
*/
awb_config.min_y = 16;
awb_config.max_y = 250;
awb_config.min_c = 16;
awb_config.max_csum = 250;
}
/* Enable the AWB gains. */
params->module_en_update |= RKISP1_CIF_ISP_MODULE_AWB_GAIN;
params->module_ens |= RKISP1_CIF_ISP_MODULE_AWB_GAIN;
/* Update the AWB measurement parameters and enable the AWB module. */
params->module_cfg_update |= RKISP1_CIF_ISP_MODULE_AWB;
params->module_en_update |= RKISP1_CIF_ISP_MODULE_AWB;
params->module_ens |= RKISP1_CIF_ISP_MODULE_AWB;
}
/**
* \copydoc libcamera::ipa::Algorithm::queueRequest
*/
void Awb::queueRequest(IPAContext &context,
[[maybe_unused]] const uint32_t frame,
IPAFrameContext &frameContext,
const ControlList &controls)
{
auto &awb = context.activeState.awb;
const auto &awbEnable = controls.get(controls::AwbEnable);
if (awbEnable && *awbEnable != awb.autoEnabled) {
awb.autoEnabled = *awbEnable;
LOG(RkISP1Awb, Debug)
<< (*awbEnable ? "Enabling" : "Disabling") << " AWB";
}
const auto &colourGains = controls.get(controls::ColourGains);
if (colourGains && !awb.autoEnabled) {
awb.gains.manual.red = (*colourGains)[0];
awb.gains.manual.blue = (*colourGains)[1];
LOG(RkISP1Awb, Debug)
<< "Set colour gains to red: " << awb.gains.manual.red
<< ", blue: " << awb.gains.manual.blue;
}
frameContext.awb.autoEnabled = awb.autoEnabled;
if (!awb.autoEnabled) {
frameContext.awb.gains.red = awb.gains.manual.red;
frameContext.awb.gains.green = 1.0;
frameContext.awb.gains.blue = awb.gains.manual.blue;
}
}
/**
* \copydoc libcamera::ipa::Algorithm::process
*/
void Awb::process(IPAContext &context,
[[maybe_unused]] const uint32_t frame,
IPAFrameContext &frameContext,
const rkisp1_stat_buffer *stats)
{
const rkisp1_cif_isp_stat *params = &stats->params;
const rkisp1_cif_isp_awb_stat *awb = ¶ms->awb;
IPAActiveState &activeState = context.activeState;
double greenMean;
double redMean;
double blueMean;
if (rgbMode_) {
greenMean = awb->awb_mean[0].mean_y_or_g;
redMean = awb->awb_mean[0].mean_cr_or_r;
blueMean = awb->awb_mean[0].mean_cb_or_b;
} else {
/* Get the YCbCr mean values */
double yMean = awb->awb_mean[0].mean_y_or_g;
double cbMean = awb->awb_mean[0].mean_cb_or_b;
double crMean = awb->awb_mean[0].mean_cr_or_r;
/*
* 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;
redMean = 1.1636 * yMean - 0.0623 * cbMean + 1.6008 * crMean;
greenMean = 1.1636 * yMean - 0.4045 * cbMean - 0.7949 * crMean;
blueMean = 1.1636 * yMean + 1.9912 * cbMean - 0.0250 * crMean;
/*
* Due to hardware rounding errors in the YCbCr means, the
* calculated RGB means may be negative. This would lead to
* negative gains, messing up calculation. Prevent this by
* clamping the means to positive values.
*/
redMean = std::max(redMean, 0.0);
greenMean = std::max(greenMean, 0.0);
blueMean = std::max(blueMean, 0.0);
}
/*
* The ISP computes the AWB means after applying the colour gains,
* divide by the gains that were used to get the raw means from the
* sensor.
*/
redMean /= frameContext.awb.gains.red;
greenMean /= frameContext.awb.gains.green;
blueMean /= frameContext.awb.gains.blue;
frameContext.awb.temperatureK = estimateCCT(redMean, greenMean, blueMean);
/*
* Estimate the red and blue gains to apply in a grey world. The green
* gain is hardcoded to 1.0.
*/
double redGain = greenMean / (redMean + 1);
double blueGain = greenMean / (blueMean + 1);
/*
* Clamp the gain values to the hardware, which expresses gains as Q2.8
* unsigned integer values. Set the minimum just above zero to avoid
* divisions by zero when computing the raw means in subsequent
* iterations.
*/
redGain = std::clamp(redGain, 1.0 / 256, 1023.0 / 256);
blueGain = std::clamp(blueGain, 1.0 / 256, 1023.0 / 256);
/* Filter the values to avoid oscillations. */
double speed = 0.2;
redGain = speed * redGain + (1 - speed) * activeState.awb.gains.automatic.red;
blueGain = speed * blueGain + (1 - speed) * activeState.awb.gains.automatic.blue;
activeState.awb.gains.automatic.red = redGain;
activeState.awb.gains.automatic.blue = blueGain;
activeState.awb.gains.automatic.green = 1.0;
LOG(RkISP1Awb, Debug) << std::showpoint
<< "Means [" << redMean << ", " << greenMean << ", " << blueMean
<< "], gains [" << activeState.awb.gains.automatic.red << ", "
<< activeState.awb.gains.automatic.green << ", "
<< activeState.awb.gains.automatic.blue << "], temp "
<< frameContext.awb.temperatureK << "K";
}
REGISTER_IPA_ALGORITHM(Awb, "Awb")
} /* namespace ipa::rkisp1::algorithms */
} /* namespace libcamera */
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