new file mode 100644
@@ -0,0 +1,102 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2025, Ideas On Board
+ *
+ * RkISP1 Compression curve
+ */
+#include "compress.h"
+
+#include <linux/videodev2.h>
+
+#include <libcamera/base/log.h>
+#include <libcamera/base/utils.h>
+
+#include "libcamera/internal/yaml_parser.h"
+
+#include "linux/rkisp1-config.h"
+
+/**
+ * \file compress.h
+ */
+
+namespace libcamera {
+
+namespace ipa::rkisp1::algorithms {
+
+/**
+ * \class Compress
+ * \brief RkISP1 Compress curve
+ *
+ * This algorithm implements support for the compressions curve in the compand
+ * block available in the i.MX8 M Plus
+ *
+ * In its current version it only supports a static gain. This is useful for
+ * the agc algorithm to compensate for exposure/gain quantization effects.
+ *
+ * This algorithm doesn't have any configuration options. It needs to be
+ * configured per frame by other algorithms.
+ *
+ * Other algorithms can check activeState.compress.supported to see if
+ * compression is available. If it is available they can configure it per frame
+ * using frameContext.compress.enable and frameContext.compress.gain.
+ */
+
+LOG_DEFINE_CATEGORY(RkISP1Compress)
+
+constexpr static int kRkISP1CompressInBits = 20;
+constexpr static int kRkISP1CompressOutBits = 12;
+
+/**
+ * \copydoc libcamera::ipa::Algorithm::configure
+ */
+int Compress::configure(IPAContext &context,
+ [[maybe_unused]] const IPACameraSensorInfo &configInfo)
+{
+ if (context.configuration.paramFormat != V4L2_META_FMT_RK_ISP1_EXT_PARAMS ||
+ !context.hw->compand) {
+ LOG(RkISP1Compress, Warning)
+ << "Compression is not supported by the hardware or kernel.";
+ return 0;
+ }
+
+ context.activeState.compress.supported = true;
+ return 0;
+}
+
+/**
+ * \copydoc libcamera::ipa::Algorithm::prepare
+ */
+void Compress::prepare([[maybe_unused]] IPAContext &context,
+ [[maybe_unused]] const uint32_t frame,
+ IPAFrameContext &frameContext,
+ RkISP1Params *params)
+{
+ auto comp = params->block<BlockType::CompandCompress>();
+ comp.setEnabled(frameContext.compress.enable);
+
+ if (!frameContext.compress.enable)
+ return;
+
+ int xmax = (1 << kRkISP1CompressInBits);
+ int ymax = (1 << kRkISP1CompressOutBits);
+ int inLogStep = std::log2(xmax / 64);
+
+ for (unsigned int i = 0; i < RKISP1_CIF_ISP_COMPAND_NUM_POINTS; i++) {
+ double x = (i + 1) * (1.0 / RKISP1_CIF_ISP_COMPAND_NUM_POINTS);
+ double y = x * frameContext.compress.gain;
+
+ comp->px[i] = inLogStep;
+ comp->x[i] = std::min<int>(x * xmax, xmax - 1);
+ comp->y[i] = std::min<int>(y * ymax, ymax - 1);
+ }
+
+ LOG(RkISP1Compress, Debug) << "Compression: " << kRkISP1CompressInBits
+ << " bits to " << kRkISP1CompressOutBits
+ << " bits gain: " << frameContext.compress.gain;
+}
+
+REGISTER_IPA_ALGORITHM(Compress, "Compress")
+
+} /* namespace ipa::rkisp1::algorithms */
+
+} /* namespace libcamera */
new file mode 100644
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2025, Ideas On Board
+ *
+ * RkISP1 Compression curve
+ */
+
+#pragma once
+
+#include "algorithm.h"
+
+namespace libcamera {
+
+namespace ipa::rkisp1::algorithms {
+
+class Compress : public Algorithm
+{
+public:
+ Compress() = default;
+ ~Compress() = default;
+
+ int configure(IPAContext &context,
+ const IPACameraSensorInfo &configInfo) override;
+ void prepare(IPAContext &context, const uint32_t frame,
+ IPAFrameContext &frameContext,
+ RkISP1Params *params) override;
+};
+
+} /* namespace ipa::rkisp1::algorithms */
+} /* namespace libcamera */
@@ -5,6 +5,7 @@ rkisp1_ipa_algorithms = files([
'awb.cpp',
'blc.cpp',
'ccm.cpp',
+ 'compress.cpp',
'cproc.cpp',
'dpcc.cpp',
'dpf.cpp',
@@ -106,6 +106,10 @@ struct IPAActiveState {
Matrix<float, 3, 3> automatic;
} ccm;
+ struct {
+ bool supported;
+ } compress;
+
struct {
int8_t brightness;
uint8_t contrast;
@@ -158,6 +162,11 @@ struct IPAFrameContext : public FrameContext {
bool update;
} cproc;
+ struct {
+ bool enable;
+ double gain;
+ } compress;
+
struct {
bool denoise;
bool update;
The i.MX8 M Plus has a compression curve inside the compand block. This curve is necessary to process HDR stitched data and is useful for other aspects like applying a digital gain to the incoming sensor data. Add a basic algorithm for the compression curve. This algorithm has a hardcoded input width of 20bit and output width of 12bit which matches the imx8mp pipeline. Only a static gain is supported in this version. Signed-off-by: Stefan Klug <stefan.klug@ideasonboard.com> --- Changes in v3: - Removed unused member - Fixed comment referencing copy-paste source - Ensure activeState.compress.supported stays false if unsupported --- src/ipa/rkisp1/algorithms/compress.cpp | 102 +++++++++++++++++++++++++ src/ipa/rkisp1/algorithms/compress.h | 30 ++++++++ src/ipa/rkisp1/algorithms/meson.build | 1 + src/ipa/rkisp1/ipa_context.h | 9 +++ 4 files changed, 142 insertions(+) create mode 100644 src/ipa/rkisp1/algorithms/compress.cpp create mode 100644 src/ipa/rkisp1/algorithms/compress.h