From bd077a11eed5bad324cfe72ae04f8d3835bb2459 Mon Sep 17 00:00:00 2001
From: Paul Elder <paul.elder@ideasonboard.com>
Date: Mon, 16 Dec 2024 16:01:48 +0900
Subject: ipa: libipa: Add Lux helper

Add a Lux helper to libipa that does the estimation of the lux level
given gain, exposure, and luminance histogram. The helper also
handles reading the reference values from the tuning file. These are
expected to be common operations of lux algorithm modules in IPAs, and
is modeled/copied from Raspberry Pi.

Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Isaac Scott <isaac.scott@ideasonboard.com>
---
 src/ipa/libipa/lux.h | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 src/ipa/libipa/lux.h

(limited to 'src/ipa/libipa/lux.h')

diff --git a/src/ipa/libipa/lux.h b/src/ipa/libipa/lux.h
new file mode 100644
index 00000000..93ca6479
--- /dev/null
+++ b/src/ipa/libipa/lux.h
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+/*
+ * Copyright (C) 2019, Raspberry Pi Ltd
+ * Copyright (C) 2024, Paul Elder <paul.elder@ideasonboard.com>
+ *
+ * Helper class that implements lux estimation
+ */
+
+#pragma once
+
+#include <libcamera/base/utils.h>
+
+namespace libcamera {
+
+class YamlObject;
+
+namespace ipa {
+
+class Histogram;
+
+class Lux
+{
+public:
+	Lux(unsigned int binSize);
+
+	int parseTuningData(const YamlObject &tuningData);
+	double estimateLux(utils::Duration exposureTime,
+			   double aGain, double dGain,
+			   const Histogram &yHist) const;
+
+private:
+	unsigned int binSize_;
+	utils::Duration referenceExposureTime_;
+	double referenceAnalogueGain_;
+	double referenceDigitalGain_;
+	double referenceY_;
+	double referenceLux_;
+};
+
+} /* namespace ipa */
+
+} /* namespace libcamera */
-- 
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