[4/5] ipa: rpi: vc4: Use a floating statistics region for a full image Y sum
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Message ID 20251017102704.3887-5-david.plowman@raspberrypi.com
State New
Headers show
Series
  • Fix and improve full image Y statistics
Related show

Commit Message

David Plowman Oct. 17, 2025, 10:05 a.m. UTC 
We're going to use a "floating statistics region" to store a full
image Y sum. The VC4 platform actually has no floating region for
this, but we can synthesize such a region as follows in software.

We know that the 15 AGC regions that we do have are arranged to cover
the whole image, and they cannot be changed. Adding up the R, G and B
values here will get us most of the way to Y. But we do also need to
know the most recent colour gains, so code must also be added to
remember the last AWB status.

With this change, algorithms can now look at the first floating region
on both VC4 and PiSP platforms to get a full image Y average value.

Signed-off-by: David Plowman <david.plowman@raspberrypi.com>
---
 src/ipa/rpi/vc4/vc4.cpp | 33 +++++++++++++++++++++++++++++++--
 1 file changed, 31 insertions(+), 2 deletions(-)

Patch
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diff --git a/src/ipa/rpi/vc4/vc4.cpp b/src/ipa/rpi/vc4/vc4.cpp
index ba43e474..fe754ace 100644
--- a/src/ipa/rpi/vc4/vc4.cpp
+++ b/src/ipa/rpi/vc4/vc4.cpp
@@ -43,6 +43,9 @@  public:
 	IpaVc4()
 		: IpaBase(), lsTable_(nullptr)
 	{
+		lastAwbStatus_.gainR = 1.0;
+		lastAwbStatus_.gainG = 1.0;
+		lastAwbStatus_.gainB = 1.0;
 	}
 
 	~IpaVc4()
@@ -81,6 +84,9 @@  private:
 	/* LS table allocation passed in from the pipeline handler. */
 	SharedFD lsTableHandle_;
 	void *lsTable_;
+
+	/* Remember the most recent AWB values. */
+	AwbStatus lastAwbStatus_;
 };
 
 int32_t IpaVc4::platformInit([[maybe_unused]] const InitParams &params, [[maybe_unused]] InitResult *result)
@@ -144,8 +150,10 @@  void IpaVc4::platformPrepareIsp([[maybe_unused]] const PrepareParams &params,
 	std::unique_lock<RPiController::Metadata> lock(rpiMetadata);
 
 	AwbStatus *awbStatus = rpiMetadata.getLocked<AwbStatus>("awb.status");
-	if (awbStatus)
+	if (awbStatus) {
 		applyAWB(awbStatus, ctrls);
+		lastAwbStatus_ = *awbStatus;
+	}
 
 	CcmStatus *ccmStatus = rpiMetadata.getLocked<CcmStatus>("ccm.status");
 	if (ccmStatus)
@@ -226,7 +234,15 @@  RPiController::StatisticsPtr IpaVc4::platformProcessStats(Span<uint8_t> mem)
 		LOG(IPARPI, Debug) << "No AGC algorithm - not copying statistics";
 		statistics->agcRegions.init(0);
 	} else {
-		statistics->agcRegions.init(hw.agcRegions);
+		uint64_t sumR = 0;
+		uint64_t sumG = 0;
+		uint64_t sumB = 0;
+		uint32_t countedSum = 0;
+		uint32_t notCountedSum = 0;
+		/* We're going to pretend there's a floating region where we will put a full image Y sum. */
+		const unsigned int numFloating = 1;
+
+		statistics->agcRegions.init(hw.agcRegions, numFloating);
 		const std::vector<double> &weights = agc->getWeights();
 		for (i = 0; i < statistics->agcRegions.numRegions(); i++) {
 			uint64_t rSum = (stats->agc_stats[i].r_sum << scale) * weights[i];
@@ -237,7 +253,20 @@  RPiController::StatisticsPtr IpaVc4::platformProcessStats(Span<uint8_t> mem)
 			statistics->agcRegions.set(i, { { rSum, gSum, bSum },
 							counted,
 							notcounted });
+
+			/* Accumulate values for the full image Y sum. */
+			sumR += stats->agc_stats[i].r_sum << scale;
+			sumG += stats->agc_stats[i].g_sum << scale;
+			sumB += stats->agc_stats[i].b_sum << scale;
+			countedSum += stats->agc_stats[i].counted;
+			notCountedSum += stats->agc_stats[i].notcounted;
 		}
+
+		/* The "floating" region has the Y sum for the entire image. */
+		uint64_t sumY = sumR * lastAwbStatus_.gainR * 0.299 + sumG * lastAwbStatus_.gainG * 0.587 +
+				sumB * lastAwbStatus_.gainB * 0.114;
+		statistics->agcRegions.setFloating(0, { { sumR, sumG, sumB, sumY },
+							countedSum, notCountedSum });
 	}
 
 	statistics->focusRegions.init(hw.focusRegions);