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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2024, Ideas On Board Oy
*
* awb.cpp - Mali C55 grey world auto white balance algorithm
*/
#include "awb.h"
#include <cmath>
#include <libcamera/base/log.h>
#include <libcamera/base/utils.h>
#include <libcamera/control_ids.h>
#include "libipa/fixedpoint.h"
namespace libcamera {
namespace ipa::mali_c55::algorithms {
LOG_DEFINE_CATEGORY(MaliC55Awb)
/* Number of frames at which we should run AWB at full speed */
static constexpr uint32_t kNumStartupFrames = 4;
Awb::Awb()
{
}
int Awb::configure([[maybe_unused]] IPAContext &context,
[[maybe_unused]] const IPACameraSensorInfo &configInfo)
{
/*
* Initially we have no idea what the colour balance will be like, so
* for the first frame we will make no assumptions and leave the R/B
* channels unmodified.
*/
context.activeState.awb.rGain = 1.0;
context.activeState.awb.bGain = 1.0;
return 0;
}
size_t Awb::fillGainsParamBlock(mali_c55_params_block block, IPAContext &context,
IPAFrameContext &frameContext)
{
block.header->type = MALI_C55_PARAM_BLOCK_AWB_GAINS;
block.header->flags = MALI_C55_PARAM_BLOCK_FL_NONE;
block.header->size = sizeof(struct mali_c55_params_awb_gains);
double rGain = context.activeState.awb.rGain;
double bGain = context.activeState.awb.bGain;
/*
* The gains here map as follows:
* gain00 = R
* gain01 = Gr
* gain10 = Gb
* gain11 = B
*
* This holds true regardless of the bayer order of the input data, as
* the mapping is done internally in the ISP.
*/
block.awb_gains->gain00 = floatingToFixedPoint<4, 8, uint16_t, double>(rGain);
block.awb_gains->gain01 = floatingToFixedPoint<4, 8, uint16_t, double>(1.0);
block.awb_gains->gain10 = floatingToFixedPoint<4, 8, uint16_t, double>(1.0);
block.awb_gains->gain11 = floatingToFixedPoint<4, 8, uint16_t, double>(bGain);
frameContext.awb.rGain = rGain;
frameContext.awb.bGain = bGain;
return sizeof(struct mali_c55_params_awb_gains);
}
size_t Awb::fillConfigParamBlock(mali_c55_params_block block)
{
block.header->type = MALI_C55_PARAM_BLOCK_AWB_CONFIG;
block.header->flags = MALI_C55_PARAM_BLOCK_FL_NONE;
block.header->size = sizeof(struct mali_c55_params_awb_config);
/* Tap the stats after the purple fringe block */
block.awb_config->tap_point = MALI_C55_AWB_STATS_TAP_PF;
/* Get R/G and B/G ratios as statistics */
block.awb_config->stats_mode = MALI_C55_AWB_MODE_RGBG;
/* Default white level */
block.awb_config->white_level = 1023;
/* Default black level */
block.awb_config->black_level = 0;
/*
* By default pixels are included who's colour ratios are bounded in a
* region (on a cr ratio x cb ratio graph) defined by four points:
* (0.25, 0.25)
* (0.25, 1.99609375)
* (1.99609375, 1.99609375)
* (1.99609375, 0.25)
*
* The ratios themselves are stored in Q4.8 format.
*
* \todo should these perhaps be tunable?
*/
block.awb_config->cr_max = 511;
block.awb_config->cr_min = 64;
block.awb_config->cb_max = 511;
block.awb_config->cb_min = 64;
/* We use the full 15x15 zoning scheme */
block.awb_config->nodes_used_horiz = 15;
block.awb_config->nodes_used_vert = 15;
/*
* We set the trimming boundaries equivalent to the main boundaries. In
* other words; no trimming.
*/
block.awb_config->cr_high = 511;
block.awb_config->cr_low = 64;
block.awb_config->cb_high = 511;
block.awb_config->cb_low = 64;
return sizeof(struct mali_c55_params_awb_config);
}
void Awb::prepare(IPAContext &context, const uint32_t frame,
IPAFrameContext &frameContext, mali_c55_params_buffer *params)
{
mali_c55_params_block block;
block.data = ¶ms->data[params->total_size];
params->total_size += fillGainsParamBlock(block, context, frameContext);
if (frame > 0)
return;
block.data = ¶ms->data[params->total_size];
params->total_size += fillConfigParamBlock(block);
}
void Awb::process(IPAContext &context, const uint32_t frame,
IPAFrameContext &frameContext, const mali_c55_stats_buffer *stats,
[[maybe_unused]] ControlList &metadata)
{
const struct mali_c55_awb_average_ratios *awb_ratios = stats->awb_ratios;
/*
* The ISP produces average R:G and B:G ratios for zones. We take the
* average of all the zones with data and simply invert them to provide
* gain figures that we can apply to approximate a grey world.
*/
unsigned int counted_zones = 0;
double rgSum = 0, bgSum = 0;
for (unsigned int i = 0; i < 225; i++) {
if (!awb_ratios[i].num_pixels)
continue;
/*
* The statistics are in Q4.8 format, so we convert to double
* here.
*/
rgSum += fixedToFloatingPoint<4, 8, double, uint16_t>(awb_ratios[i].avg_rg_gr);
bgSum += fixedToFloatingPoint<4, 8, double, uint16_t>(awb_ratios[i].avg_bg_br);
counted_zones++;
}
/*
* Sometimes the first frame's statistics have no valid pixels, in which
* case we'll just assume a grey world until they say otherwise.
*/
double rgAvg, bgAvg;
if (!counted_zones) {
rgAvg = 1.0;
bgAvg = 1.0;
} else {
rgAvg = rgSum / counted_zones;
bgAvg = bgSum / counted_zones;
}
/*
* The statistics are generated _after_ white balancing is performed in
* the ISP. To get the true ratio we therefore have to adjust the stats
* figure by the gains that were applied when the statistics for this
* frame were generated.
*/
double rRatio = rgAvg / frameContext.awb.rGain;
double bRatio = bgAvg / frameContext.awb.bGain;
/*
* And then we can simply invert the ratio to find the gain we should
* apply.
*/
double rGain = 1 / rRatio;
double bGain = 1 / bRatio;
/*
* Running at full speed, this algorithm results in oscillations in the
* colour balance. To remove those we dampen the speed at which it makes
* changes in gain, unless we're in the startup phase in which case we
* want to fix the miscolouring as quickly as possible.
*/
double speed = frame < kNumStartupFrames ? 1.0 : 0.2;
rGain = speed * rGain + context.activeState.awb.rGain * (1.0 - speed);
bGain = speed * bGain + context.activeState.awb.bGain * (1.0 - speed);
context.activeState.awb.rGain = rGain;
context.activeState.awb.bGain = bGain;
metadata.set(controls::ColourGains, {
static_cast<float>(frameContext.awb.rGain),
static_cast<float>(frameContext.awb.bGain),
});
LOG(MaliC55Awb, Debug) << "For frame number " << frame << ": "
<< "Average R/G Ratio: " << rgAvg
<< ", Average B/G Ratio: " << bgAvg
<< "\nrGain applied to this frame: " << frameContext.awb.rGain
<< ", bGain applied to this frame: " << frameContext.awb.bGain
<< "\nrGain to apply: " << context.activeState.awb.rGain
<< ", bGain to apply: " << context.activeState.awb.bGain;
}
REGISTER_IPA_ALGORITHM(Awb, "Awb")
} /* namespace ipa::mali_c55::algorithms */
} /* namespace libcamera */
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