[v13,7/7] libcamera: software_isp: debayer_egl: Add LSC support
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Message ID 20260810201957.19623-8-mzamazal@redhat.com
State New
Headers show
Series
  • LSC for SoftISP simple pipeline
Related show

Commit Message

Milan Zamazal Aug. 10, 2026, 8:19 p.m. UTC 
From: Xander Pronk <xander.c.pronk@gmail.com>

Add support for passing the LSC table from debayerParams to the shaders.

We use 8-bit texture with the original UQ<2, 6> values to avoid trouble
with floats.  32-bit floats don't work in my environment and 16-bit
floats may not be supported in all OpenGL environments.

When LSC is disabled by the runtime control, we provide a constant 1.0
correction table, i.e. a no-op table.  This is preferred to having a
runtime flag, to not disturb GPU computation with runtime switches,
assuming that disabling LSC in runtime is not a common use case.

The LSC texture is created once and then updated.  The texture creation
cannot be done in `configure', because of a different thread.

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    |  2 ++
 src/libcamera/software_isp/debayer.cpp        |  5 +++
 src/libcamera/software_isp/debayer_egl.cpp    | 36 ++++++++++++++++++-
 src/libcamera/software_isp/debayer_egl.h      |  7 ++++
 4 files changed, 49 insertions(+), 1 deletion(-)

Patch
diff mbox series 

diff --git a/include/libcamera/internal/software_isp/debayer_params.h b/include/libcamera/internal/software_isp/debayer_params.h
index b7860c9dd..1e0b5b553 100644
--- a/include/libcamera/internal/software_isp/debayer_params.h
+++ b/include/libcamera/internal/software_isp/debayer_params.h
@@ -33,6 +33,8 @@  struct DebayerParams {
 	 **/
 	static constexpr unsigned int kLscGridSize = 17;
 	static constexpr unsigned int kLscValuesPerCell = 4;
+	static constexpr unsigned int kLscBytesPerCell =
+		kLscValuesPerCell * sizeof(uint8_t);
 	using LscLookupTable =
 		std::array<uint8_t, kLscGridSize * kLscGridSize * kLscValuesPerCell>;
 	static constexpr auto identityLscLut = [] {
diff --git a/src/libcamera/software_isp/debayer.cpp b/src/libcamera/software_isp/debayer.cpp
index 8295b8fc2..4f6659000 100644
--- a/src/libcamera/software_isp/debayer.cpp
+++ b/src/libcamera/software_isp/debayer.cpp
@@ -53,6 +53,11 @@  namespace libcamera {
  * \brief Number of pixel values per each of the lens shading grid areas
  */
 
+/**
+ * \var DebayerParams::kLscBytesPerCell
+ * \brief Number of bytes per each of the lens shading grid areas
+ */
+
 /**
  * \typedef DebayerParams::LscLookupTable
  * \brief Lookup table for lens shading correction
diff --git a/src/libcamera/software_isp/debayer_egl.cpp b/src/libcamera/software_isp/debayer_egl.cpp
index 5227d2bbd..941fdc914 100644
--- a/src/libcamera/software_isp/debayer_egl.cpp
+++ b/src/libcamera/software_isp/debayer_egl.cpp
@@ -115,6 +115,8 @@  int DebayerEGL::getShaderVariableLocations(void)
 	textureUniformBayerFirstRed_ = glGetUniformLocation(programId_, "tex_bayer_first_red");
 	textureUniformProjMatrix_ = glGetUniformLocation(programId_, "proj_matrix");
 
+	textureUniformLsc_ = glGetUniformLocation(programId_, "lsc_tex");
+
 	LOG(Debayer, Debug) << "vertexIn " << attributeVertex_ << " textureIn " << attributeTexture_
 			    << " tex_y " << textureUniformBayerDataIn_
 			    << " awb " << awbUniformDataIn_
@@ -126,7 +128,8 @@  int DebayerEGL::getShaderVariableLocations(void)
 			    << " tex_size " << textureUniformSize_
 			    << " stride_factor " << textureUniformStrideFactor_
 			    << " tex_bayer_first_red " << textureUniformBayerFirstRed_
-			    << " proj_matrix " << textureUniformProjMatrix_;
+			    << " proj_matrix " << textureUniformProjMatrix_
+			    << " tex_lsc " << textureUniformLsc_;
 	return 0;
 }
 
@@ -143,6 +146,9 @@  int DebayerEGL::initBayerShaders(PixelFormat inputFormat, PixelFormat outputForm
 	/* Specify GL_OES_EGL_image_external */
 	egl_.pushEnv(shaderEnv, "#extension GL_OES_EGL_image_external: enable");
 
+	if (lscEnabled_)
+		egl_.pushEnv(shaderEnv, "#define APPLY_LSC");
+
 	/*
 	 * Tell shaders how to re-order output taking account of how the pixels
 	 * are actually stored by EGL.
@@ -467,6 +473,31 @@  void DebayerEGL::setShaderVariableValues(eGLImage &eglImageIn, const DebayerPara
 	glUniformMatrix3fv(ccmUniformDataIn_, 1, GL_TRUE, params.combinedMatrix.data().data());
 	LOG(Debayer, Debug) << " ccmUniformDataIn_ " << ccmUniformDataIn_ << " data " << params.combinedMatrix;
 
+	if (lscEnabled_) {
+		bool create = !eglImageLscLookup_;
+		if (create) {
+			constexpr unsigned int gridSize = DebayerParams::kLscGridSize;
+			const unsigned int stride = gridSize * DebayerParams::kLscBytesPerCell;
+			eglImageLscLookup_ =
+				std::make_unique<eGLImage>(GL_RGBA,
+							   gridSize,
+							   gridSize,
+							   stride,
+							   GL_TEXTURE2,
+							   2);
+		}
+		glUniform1i(textureUniformLsc_, eglImageLscLookup_->texture_unit_uniform_id_);
+		if (params.lscLutVersion != lscLutVersion_) {
+			if (create)
+				egl_.createTexture2D(*eglImageLscLookup_, eglImageLscLookup_->format_, GL_UNSIGNED_BYTE,
+						     params.lscLut.data(), GL_LINEAR);
+			else
+				egl_.updateTexture2D(*eglImageLscLookup_, params.lscLut.data());
+
+			lscLutVersion_ = params.lscLutVersion;
+		}
+	}
+
 	/*
 	 * 0 = Red, 1 = Green, 2 = Blue
 	 */
@@ -687,6 +718,9 @@  void DebayerEGL::stop()
 	eglImageOutCache_.clear();
 	eglImageInCache_.clear();
 
+	eglImageLscLookup_.reset();
+	lscLutVersion_.reset();
+
 	if (programId_)
 		glDeleteProgram(programId_);
 }
diff --git a/src/libcamera/software_isp/debayer_egl.h b/src/libcamera/software_isp/debayer_egl.h
index a64dc925a..c2a08fb06 100644
--- a/src/libcamera/software_isp/debayer_egl.h
+++ b/src/libcamera/software_isp/debayer_egl.h
@@ -83,7 +83,11 @@  private:
 	unsigned int inputBufferCount_;
 	unsigned int outputBufferCount_;
 
+	/* LSC lookup table */
+	std::unique_ptr<eGLImage> eglImageLscLookup_;
 	bool lscEnabled_;
+	std::optional<uint64_t> lscLutVersion_;
+
 	/* Shader parameters */
 	float firstRed_x_;
 	float firstRed_y_;
@@ -100,6 +104,9 @@  private:
 	/* Per-frame AWB gains */
 	GLint awbUniformDataIn_;
 
+	/* Lens shading correction */
+	GLint textureUniformLsc_;
+
 	/* Represent per-frame CCM as a uniform vector of floats 3 x 3 */
 	GLint ccmUniformDataIn_;