1 files changed, 71 insertions, 0 deletions
diff --git a/src/ipa/raspberrypi/controller/rpi/noise.cpp b/src/ipa/raspberrypi/controller/rpi/noise.cpp
new file mode 100644
index 00000000..2209d791
--- /dev/null
+++ b/src/ipa/raspberrypi/controller/rpi/noise.cpp
@@ -0,0 +1,71 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+/*
+ * Copyright (C) 2019, Raspberry Pi (Trading) Limited
+ *
+ * noise.cpp - Noise control algorithm
+ */
+
+#include <math.h>
+
+#include "../device_status.h"
+#include "../logging.hpp"
+#include "../noise_status.h"
+
+#include "noise.hpp"
+
+using namespace RPi;
+
+#define NAME "rpi.noise"
+
+Noise::Noise(Controller *controller)
+	: Algorithm(controller), mode_factor_(1.0)
+{
+}
+
+char const *Noise::Name() const
+{
+	return NAME;
+}
+
+void Noise::SwitchMode(CameraMode const &camera_mode)
+{
+	// For example, we would expect a 2x2 binned mode to have a "noise
+	// factor" of sqrt(2x2) = 2. (can't be less than one, right?)
+	mode_factor_ = std::max(1.0, camera_mode.noise_factor);
+}
+
+void Noise::Read(boost::property_tree::ptree const &params)
+{
+	RPI_LOG(Name());
+	reference_constant_ = params.get<double>("reference_constant");
+	reference_slope_ = params.get<double>("reference_slope");
+}
+
+void Noise::Prepare(Metadata *image_metadata)
+{
+	struct DeviceStatus device_status;
+	device_status.analogue_gain = 1.0; // keep compiler calm
+	if (image_metadata->Get("device.status", device_status) == 0) {
+		// There is a slight question as to exactly how the noise
+		// profile, specifically the constant part of it, scales. For
+		// now we assume it all scales the same, and we'll revisit this
+		// if it proves substantially wrong.  NOTE: we may also want to
+		// make some adjustments based on the camera mode (such as
+		// binning), if we knew how to discover it...
+		double factor = sqrt(device_status.analogue_gain) / mode_factor_;
+		struct NoiseStatus status;
+		status.noise_constant = reference_constant_ * factor;
+		status.noise_slope = reference_slope_ * factor;
+		image_metadata->Set("noise.status", status);
+		RPI_LOG(Name() << ": constant " << status.noise_constant
+			       << " slope " << status.noise_slope);
+	} else
+		RPI_WARN(Name() << " no metadata");
+}
+
+// Register algorithm with the system.
+static Algorithm *Create(Controller *controller)
+{
+	return new Noise(controller);
+}
+static RegisterAlgorithm reg(NAME, &Create);