[libcamera-devel] [PATCH v3 10/19] ipa: ipu3: tonemapping: Add the documentation for ToneMapping

[Jean-Michel Hautbois]

The Tone mapping algorithm is currently undocumented.

Provide an introduction and overview to the implementation as the class
definition and document how the algorithm operates in the process and
prepare methods.

Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois at ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>

---
v3:
- rename gamma control as tone mapping
---
 src/ipa/ipu3/algorithms/tone_mapping.cpp | 30 +++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/src/ipa/ipu3/algorithms/tone_mapping.cpp b/src/ipa/ipu3/algorithms/tone_mapping.cpp
index 8fa8c7e9..832e5670 100644
--- a/src/ipa/ipu3/algorithms/tone_mapping.cpp
+++ b/src/ipa/ipu3/algorithms/tone_mapping.cpp
@@ -10,10 +10,22 @@
 #include <cmath>
 #include <string.h>
 
+/**
+ * \file tone_mapping.h
+ */
+
 namespace libcamera {
 
 namespace ipa::ipu3::algorithms {
 
+/**
+ * \class ToneMapping
+ * \brief A class to handle tone mapping based on gamma
+ *
+ * This algorithm improves the image dynamic using a look-up table which is
+ * generated based on a gamma parameter.
+ */
+
 ToneMapping::ToneMapping()
 	: gamma_(1.0)
 {
@@ -35,6 +47,14 @@ int ToneMapping::configure(IPAContext &context,
 	return 0;
 }
 
+/**
+ * \brief Fill in the parameter structure, and enable gamma control
+ * \param context The shared IPA context
+ * \param params The IPU3 parameters
+ *
+ * Populate the IPU3 parameter structure with our tone mapping look up table and
+ * enable the gamma control module in the processing blocks.
+ */
 void ToneMapping::prepare([[maybe_unused]] IPAContext &context,
 			  ipu3_uapi_params *params)
 {
@@ -49,7 +69,15 @@ void ToneMapping::prepare([[maybe_unused]] IPAContext &context,
 	params->acc_param.gamma.gc_ctrl.enable = 1;
 }
 
-void ToneMapping::process([[maybe_unused]] IPAContext &context,
+/**
+ * \brief Calculate the tone mapping look up table
+ * \param context The shared IPA context
+ * \param stats The IPU3 statistics and ISP results
+ *
+ * The tone mapping look up table is generated as an inverse power curve from
+ * our gamma setting.
+ */
+void ToneMapping::process(IPAContext &context,
 			  [[maybe_unused]] const ipu3_uapi_stats_3a *stats)
 {
 	/*
-- 
2.32.0