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ipa: raspberrypi: Normalise region sums to 16-bits

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The VC4 ISP uses a pipeline bit-depth of 13-bits. The AGC algorithm needs to
know this bit-depth when computing the Y value for the image.

Instead of hardcoding the VC4 bit-depth in the AGC source code, normalise all
region sums to 16-bits when filling the Statistics structure. AWB and ALSC are
agnostic about pipeline depth, so do not need changing.

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
Reviewed-by: David Plowman <david.plowman@raspberrypi.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
This commit is contained in:
Naushir Patuck 2023-02-03 09:17:34 +00:00 • committed by Kieran Bingham
parent 6d60f264d1
commit 61b43e50e7
2 changed files with 17 additions and 12 deletions
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11
src/ipa/raspberrypi/controller/rpi/agc.cpp
View file

@ -28,8 +28,6 @@ LOG_DEFINE_CATEGORY(RPiAgc)
#define NAME "rpi.agc"
static constexpr unsigned int PipelineBits = 13; /* seems to be a 13-bit pipeline */
int AgcMeteringMode::read(const libcamera::YamlObject &params)
{
const YamlObject &yamlWeights = params["weights"];
@ -586,6 +584,7 @@ void Agc::fetchAwbStatus(Metadata *imageMetadata)
static double computeInitialY(StatisticsPtr &stats, AwbStatus const &awb,
double weights[], double gain)
{
constexpr unsigned int maxVal = 1 << Statistics::NormalisationFactorPow2;
/*
* Note how the calculation below means that equal weights give you
* "average" metering (i.e. all pixels equally important).
@ -593,9 +592,9 @@ static double computeInitialY(StatisticsPtr &stats, AwbStatus const &awb,
double rSum = 0, gSum = 0, bSum = 0, pixelSum = 0;
for (unsigned int i = 0; i < stats->agcRegions.numRegions(); i++) {
auto &region = stats->agcRegions.get(i);
double rAcc = std::min<double>(region.val.rSum * gain, ((1 << PipelineBits) - 1) * region.counted);
double gAcc = std::min<double>(region.val.gSum * gain, ((1 << PipelineBits) - 1) * region.counted);
double bAcc = std::min<double>(region.val.bSum * gain, ((1 << PipelineBits) - 1) * region.counted);
double rAcc = std::min<double>(region.val.rSum * gain, (maxVal - 1) * region.counted);
double gAcc = std::min<double>(region.val.gSum * gain, (maxVal - 1) * region.counted);
double bAcc = std::min<double>(region.val.bSum * gain, (maxVal - 1) * region.counted);
rSum += rAcc * weights[i];
gSum += gAcc * weights[i];
bSum += bAcc * weights[i];
@ -608,7 +607,7 @@ static double computeInitialY(StatisticsPtr &stats, AwbStatus const &awb,
double ySum = rSum * awb.gainR * .299 +
gSum * awb.gainG * .587 +
bSum * awb.gainB * .114;
return ySum / pixelSum / (1 << PipelineBits);
return ySum / pixelSum / maxVal;
}
/*

18
src/ipa/raspberrypi/raspberrypi.cpp
View file

@ -1377,11 +1377,17 @@ RPiController::StatisticsPtr IPARPi::fillStatistics(bcm2835_isp_stats *stats) co
/* RGB histograms are not used, so do not populate them. */
statistics->yHist = RPiController::Histogram(stats->hist[0].g_hist, NUM_HISTOGRAM_BINS);
/*
* All region sums are based on a 13-bit pipeline bit-depth. Normalise
* this to 16-bits for the AGC/AWB/ALSC algorithms.
*/
constexpr unsigned int scale = Statistics::NormalisationFactorPow2 - 13;
statistics->awbRegions.init({ DEFAULT_AWB_REGIONS_X, DEFAULT_AWB_REGIONS_Y });
for (i = 0; i < statistics->awbRegions.numRegions(); i++)
statistics->awbRegions.set(i, { { stats->awb_stats[i].r_sum,
stats->awb_stats[i].g_sum,
stats->awb_stats[i].b_sum },
statistics->awbRegions.set(i, { { stats->awb_stats[i].r_sum << scale,
stats->awb_stats[i].g_sum << scale,
stats->awb_stats[i].b_sum << scale },
stats->awb_stats[i].counted,
stats->awb_stats[i].notcounted });
@ -1391,9 +1397,9 @@ RPiController::StatisticsPtr IPARPi::fillStatistics(bcm2835_isp_stats *stats) co
*/
statistics->agcRegions.init(15);
for (i = 0; i < statistics->agcRegions.numRegions(); i++)
statistics->agcRegions.set(i, { { stats->agc_stats[i].r_sum,
stats->agc_stats[i].g_sum,
stats->agc_stats[i].b_sum },
statistics->agcRegions.set(i, { { stats->agc_stats[i].r_sum << scale,
stats->agc_stats[i].g_sum << scale,
stats->agc_stats[i].b_sum << scale },
stats->agc_stats[i].counted,
stats->awb_stats[i].notcounted });