From e5e0ce6573ac91a76954eeaf89cd309a48fd333d Mon Sep 17 00:00:00 2001
From: Kieran Bingham <kieran.bingham@ideasonboard.com>
Date: Wed, 4 Aug 2021 14:29:04 +0100
Subject: ipa: ipu3: Introduce a modular contrast algorithm

Implement a new modular framework for algorithms with a common context
structure that is passed to each algorithm through a common API.

The initial algorithm is chosen to configure the gamma contrast curve
which replicates the implementation from AWB for simplicity.

Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
---
 src/ipa/ipu3/algorithms/contrast.cpp | 46 ++++++++++++++++++++++++++++++++++++
 src/ipa/ipu3/algorithms/contrast.h   | 32 +++++++++++++++++++++++++
 src/ipa/ipu3/algorithms/meson.build  |  1 +
 src/ipa/ipu3/ipu3.cpp                |  5 ++++
 4 files changed, 84 insertions(+)
 create mode 100644 src/ipa/ipu3/algorithms/contrast.cpp
 create mode 100644 src/ipa/ipu3/algorithms/contrast.h

diff --git a/src/ipa/ipu3/algorithms/contrast.cpp b/src/ipa/ipu3/algorithms/contrast.cpp
new file mode 100644
index 00000000..890dc3ff
--- /dev/null
+++ b/src/ipa/ipu3/algorithms/contrast.cpp
@@ -0,0 +1,46 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2021, Ideas On Board
+ *
+ * constrast.cpp - IPU3 Contrast and Gamma control
+ */
+
+#include "contrast.h"
+
+#include <cmath>
+
+#include <libcamera/base/log.h>
+
+namespace libcamera {
+
+namespace ipa::ipu3::algorithms {
+
+LOG_DEFINE_CATEGORY(IPU3Contrast)
+
+Contrast::Contrast()
+	: gamma_(1.0)
+{
+}
+
+void Contrast::initialise(IPAContext &context)
+{
+	ipu3_uapi_params &params = context.params;
+
+	/* Limit the gamma effect for now */
+	gamma_ = 1.1;
+
+	/* Plot the gamma curve into the look up table */
+	for (uint32_t i = 0; i < 256; i++) {
+		double j = i / 255.0;
+		double gamma = std::pow(j, 1.0 / gamma_);
+
+		/* The maximum value 255 is represented on 13 bits in the IPU3 */
+		params.acc_param.gamma.gc_lut.lut[i] = gamma * 8191;
+	}
+
+	LOG(IPU3Contrast, Info) << "Processed Gamma Curve";
+}
+
+} /* namespace ipa::ipu3::algorithms */
+
+} /* namespace libcamera */
diff --git a/src/ipa/ipu3/algorithms/contrast.h b/src/ipa/ipu3/algorithms/contrast.h
new file mode 100644
index 00000000..cd1b0060
--- /dev/null
+++ b/src/ipa/ipu3/algorithms/contrast.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2021, Google
+ *
+ * constrast.h - IPU3 Contrast and Gamma control
+ */
+#ifndef __LIBCAMERA_IPU3_ALGORITHMS_CONTRAST_H__
+#define __LIBCAMERA_IPU3_ALGORITHMS_CONTRAST_H__
+
+#include "algorithm.h"
+
+namespace libcamera {
+
+namespace ipa::ipu3::algorithms {
+
+class Contrast : public Algorithm
+{
+public:
+	Contrast();
+	~Contrast() = default;
+
+	void initialise(IPAContext &context);
+
+private:
+	double gamma_;
+};
+
+} /* namespace ipa::ipu3::algorithms */
+
+} /* namespace libcamera */
+
+#endif /* __LIBCAMERA_IPU3_ALGORITHMS_CONTRAST_H__ */
diff --git a/src/ipa/ipu3/algorithms/meson.build b/src/ipa/ipu3/algorithms/meson.build
index 67148333..f71d1e61 100644
--- a/src/ipa/ipu3/algorithms/meson.build
+++ b/src/ipa/ipu3/algorithms/meson.build
@@ -1,4 +1,5 @@
 # SPDX-License-Identifier: CC0-1.0
 
 ipu3_ipa_algorithms = files([
+    'contrast.cpp',
 ])
diff --git a/src/ipa/ipu3/ipu3.cpp b/src/ipa/ipu3/ipu3.cpp
index 1d89c28b..0bfb7c49 100644
--- a/src/ipa/ipu3/ipu3.cpp
+++ b/src/ipa/ipu3/ipu3.cpp
@@ -29,6 +29,8 @@
 #include "ipu3_awb.h"
 #include "libipa/camera_sensor_helper.h"
 
+#include "algorithms/contrast.h"
+
 static constexpr uint32_t kMaxCellWidthPerSet = 160;
 static constexpr uint32_t kMaxCellHeightPerSet = 56;
 
@@ -103,6 +105,9 @@ int IPAIPU3::init(const IPASettings &settings)
 		return -ENODEV;
 	}
 
+	/* Construct our Algorithms */
+	algorithms_.emplace_back(algorithms::Contrast());
+
 	initialiseAlgorithms();
 
 	return 0;
-- 
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