[RFC,v6,2/6] libcamera: software_isp: Add LSC data to DebayerParams
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Message ID 20260708141436.119165-3-mzamazal@redhat.com
State New
Headers show
Series
  • LSC for SoftISP simple pipeline
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Commit Message

Milan Zamazal July 8, 2026, 2:14 p.m. UTC 
From: Xander Pronk <xander.c.pronk@gmail.com>

Add a lookup table for grid-based lens shading correction to debayer
params.  The lookup table is in the format of an RGB texture to be
passed to debayering.

The parameter is filled in by Lsc algorithm implemented in a followup
patch.  If the algorithm is not enabled, the parameter content is
arbitrary and the parameter may not be used.  The parameter is currently
unused, its handling is implemented in a followup patch.

There is no special meaning about the selected grid size, it's
just one of the smaller common sizes.

Co-developed-by: Rick ten Wolde <rick_libcamera@wolde.info>
Signed-off-by: Rick ten Wolde <rick_libcamera@wolde.info>
Signed-off-by: Xander Pronk <xander.c.pronk@gmail.com>
Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
---
 .../internal/software_isp/debayer_params.h    |  9 +++++
 src/libcamera/software_isp/debayer.cpp        | 33 +++++++++++++++++++
 2 files changed, 42 insertions(+)

Patch
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diff --git a/include/libcamera/internal/software_isp/debayer_params.h b/include/libcamera/internal/software_isp/debayer_params.h
index 1074720d7..4eb6c7e8d 100644
--- a/include/libcamera/internal/software_isp/debayer_params.h
+++ b/include/libcamera/internal/software_isp/debayer_params.h
@@ -10,6 +10,7 @@ 
 
 #pragma once
 
+#include <array>
 #include <stdint.h>
 
 #include "libcamera/internal/matrix.h"
@@ -25,6 +26,14 @@  struct DebayerParams {
 	float gamma = 1.0;
 	float contrastExp = 1.0;
 	RGB<double> gains = RGB<double>({ 1.0, 1.0, 1.0 });
+
+	static constexpr unsigned int kLscGridSize = 16;
+	static constexpr unsigned int kLscValuesPerCell = 3;
+	using LscValueType = float;
+	using LscLookupTable =
+		std::array<LscValueType, kLscGridSize * kLscGridSize * kLscValuesPerCell>;
+	LscLookupTable lscLut{};
+	bool lscEnabled;
 };
 
 } /* namespace libcamera */
diff --git a/src/libcamera/software_isp/debayer.cpp b/src/libcamera/software_isp/debayer.cpp
index 56446f55d..5a0102a27 100644
--- a/src/libcamera/software_isp/debayer.cpp
+++ b/src/libcamera/software_isp/debayer.cpp
@@ -43,6 +43,39 @@  namespace libcamera {
  * \brief Contrast value to be used as an exponent
  */
 
+/**
+ * \var DebayerParams::kLscGridSize
+ * \brief Number of lens shading grid areas in one direction
+ */
+
+/**
+ * \var DebayerParams::kLscValuesPerCell
+ * \brief Number of pixel values per each of the lens shading grid areas
+ */
+
+/**
+ * \typedef DebayerParams::LscValueType
+ * \brief Type of LSC grid values
+ */
+
+/**
+ * \typedef DebayerParams::LscLookupTable
+ * \brief Lookup table for lens shading correction
+ *
+ * It's an array of values to be later used as a texture.
+ * The values are in row - column - RGB order.
+ */
+
+/**
+ * \var DebayerParams::lscLut
+ * \brief Lens shading lookup table
+ */
+
+/**
+ * \var DebayerParams::lscEnabled
+ * \brief Whether lens shading should be applied
+ */
+
 /**
  * \class Debayer
  * \brief Base debayering class