ipa: rkisp1: Add support of Lens Shading Correction control

The Lens Shading Correction algorithm applies multipliers to all pixels
to compensate for the lens shading effect. The coefficients are
specified in a downscaled table in the YAML tuning file.

Signed-off-by: Florian Sylvestre <fsylvestre@baylibre.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

1 files changed, 178 insertions, 0 deletions

diff --git a/src/ipa/rkisp1/algorithms/lsc.cpp b/src/ipa/rkisp1/algorithms/lsc.cpp
new file mode 100644
index 00000000..05c8c0da
--- /dev/null
+++ b/src/ipa/rkisp1/algorithms/lsc.cpp
@@ -0,0 +1,178 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2021-2022, Ideas On Board
+ *
+ * lsc.cpp - RkISP1 Lens Shading Correction control
+ */
+
+#include "lsc.h"
+
+#include <cmath>
+#include <numeric>
+
+#include <libcamera/base/log.h>
+#include <libcamera/base/utils.h>
+
+#include "libcamera/internal/yaml_parser.h"
+
+#include "linux/rkisp1-config.h"
+
+/**
+ * \file lsc.h
+ */
+
+namespace libcamera {
+
+namespace ipa::rkisp1::algorithms {
+
+/**
+ * \class LensShadingCorrection
+ * \brief RkISP1 Lens Shading Correction control
+ *
+ * Due to the optical characteristics of the lens, the light intensity received
+ * by the sensor is not uniform.
+ *
+ * The Lens Shading Correction algorithm applies multipliers to all pixels
+ * to compensate for the lens shading effect. The coefficients are
+ * specified in a downscaled table in the YAML tuning file.
+ */
+
+LOG_DEFINE_CATEGORY(RkISP1Lsc)
+
+static std::vector<double> parseSizes(const YamlObject &tuningData,
+				      const char *prop)
+{
+	std::vector<double> sizes =
+		tuningData[prop].getList<double>().value_or(utils::defopt);
+	if (sizes.size() != RKISP1_CIF_ISP_LSC_SECTORS_TBL_SIZE) {
+		LOG(RkISP1Lsc, Error)
+			<< "Invalid '" << prop << "' values: expected "
+			<< RKISP1_CIF_ISP_LSC_SECTORS_TBL_SIZE
+			<< " elements, got " << sizes.size();
+		return {};
+	}
+
+	/*
+	 * The sum of all elements must be 0.5 to satisfy hardware constraints.
+	 * Validate it here, allowing a 1% tolerance as rounding errors may
+	 * prevent an exact match (further adjustments will be performed in
+	 * LensShadingCorrection::prepare()).
+	 */
+	float sum = std::accumulate(sizes.begin(), sizes.end(), 0.0f);
+	if (sum < 0.495 || sum > 0.505) {
+		LOG(RkISP1Lsc, Error)
+			<< "Invalid '" << prop << "' values: sum of the elements"
+			<< " should be 0.5, got " << sum;
+		return {};
+	}
+
+	return sizes;
+}
+
+static std::vector<uint16_t> parseTable(const YamlObject &tuningData,
+					const char *prop)
+{
+	static constexpr unsigned int kLscNumSamples =
+		RKISP1_CIF_ISP_LSC_SAMPLES_MAX * RKISP1_CIF_ISP_LSC_SAMPLES_MAX;
+
+	std::vector<uint16_t> table =
+		tuningData[prop].getList<uint16_t>().value_or(utils::defopt);
+	if (table.size() != kLscNumSamples) {
+		LOG(RkISP1Lsc, Error)
+			<< "Invalid '" << prop << "' values: expected "
+			<< kLscNumSamples
+			<< " elements, got " << table.size();
+		return {};
+	}
+
+	return table;
+}
+
+LensShadingCorrection::LensShadingCorrection()
+	: initialized_(false)
+{
+}
+
+/**
+ * \copydoc libcamera::ipa::Algorithm::init
+ */
+int LensShadingCorrection::init([[maybe_unused]] IPAContext &context,
+				const YamlObject &tuningData)
+{
+	xSize_ = parseSizes(tuningData, "x-size");
+	ySize_ = parseSizes(tuningData, "y-size");
+
+	if (xSize_.empty() || ySize_.empty())
+		return -EINVAL;
+
+	rData_ = parseTable(tuningData, "r");
+	grData_ = parseTable(tuningData, "gr");
+	gbData_ = parseTable(tuningData, "gb");
+	bData_ = parseTable(tuningData, "b");
+
+	if (rData_.empty() || grData_.empty() ||
+	    gbData_.empty() || bData_.empty())
+		return -EINVAL;
+
+	initialized_ = true;
+
+	return 0;
+}
+
+/**
+ * \copydoc libcamera::ipa::Algorithm::prepare
+ */
+void LensShadingCorrection::prepare(IPAContext &context,
+				    rkisp1_params_cfg *params)
+{
+	if (context.frameContext.frameCount > 0)
+		return;
+
+	if (!initialized_)
+		return;
+
+	struct rkisp1_cif_isp_lsc_config &config = params->others.lsc_config;
+	const Size &size = context.configuration.sensor.size;
+	Size totalSize{};
+
+	for (unsigned int i = 0; i < RKISP1_CIF_ISP_LSC_SECTORS_TBL_SIZE; ++i) {
+		config.x_size_tbl[i] = xSize_[i] * size.width;
+		config.y_size_tbl[i] = ySize_[i] * size.height;
+
+		/*
+		 * To prevent unexpected behavior of the ISP, the sum of x_size_tbl and
+		 * y_size_tbl items shall be equal to respectively size.width/2 and
+		 * size.height/2. Enforce it by computing the last tables value to avoid
+		 * rounding-induced errors.
+		 */
+		if (i == RKISP1_CIF_ISP_LSC_SECTORS_TBL_SIZE - 1) {
+			config.x_size_tbl[i] = size.width / 2 - totalSize.width;
+			config.y_size_tbl[i] = size.height / 2 - totalSize.height;
+		}
+
+		totalSize.width += config.x_size_tbl[i];
+		totalSize.height += config.y_size_tbl[i];
+
+		config.x_grad_tbl[i] = std::round(32768 / config.x_size_tbl[i]);
+		config.y_grad_tbl[i] = std::round(32768 / config.y_size_tbl[i]);
+	}
+
+	std::copy(rData_.begin(), rData_.end(),
+		  &params->others.lsc_config.r_data_tbl[0][0]);
+	std::copy(grData_.begin(), grData_.end(),
+		  &params->others.lsc_config.gr_data_tbl[0][0]);
+	std::copy(gbData_.begin(), gbData_.end(),
+		  &params->others.lsc_config.gb_data_tbl[0][0]);
+	std::copy(bData_.begin(), bData_.end(),
+		  &params->others.lsc_config.b_data_tbl[0][0]);
+
+	params->module_en_update |= RKISP1_CIF_ISP_MODULE_LSC;
+	params->module_ens |= RKISP1_CIF_ISP_MODULE_LSC;
+	params->module_cfg_update |= RKISP1_CIF_ISP_MODULE_LSC;
+}
+
+REGISTER_IPA_ALGORITHM(LensShadingCorrection, "LensShadingCorrection")
+
+} /* namespace ipa::rkisp1::algorithms */
+
+} /* namespace libcamera */