[libcamera-devel] [PATCH 3/4] libipa: camera_sensor_helper: Add IMX290 helper
Laurent Pinchart
laurent.pinchart at ideasonboard.com
Mon Mar 28 14:03:35 CEST 2022
The IMX290 is a Sony sensor that expresses its gain in 0.3dB units. It
thus maps to the exponential gain model.
Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
src/ipa/libipa/camera_sensor_helper.cpp | 31 +++++++++++++++++++++++++
1 file changed, 31 insertions(+)
diff --git a/src/ipa/libipa/camera_sensor_helper.cpp b/src/ipa/libipa/camera_sensor_helper.cpp
index 7bb999e19102..136b9f6bc3c5 100644
--- a/src/ipa/libipa/camera_sensor_helper.cpp
+++ b/src/ipa/libipa/camera_sensor_helper.cpp
@@ -332,6 +332,26 @@ std::vector<CameraSensorHelperFactory *> &CameraSensorHelperFactory::factories()
#ifndef __DOXYGEN__
+/*
+ * Helper function to compute the m parameter of the exponential gain model
+ * when the gain code is expressed in dB.
+ */
+static constexpr double expGainDb(double step)
+{
+ constexpr double log2_10 = 3.321928094887362;
+
+ /*
+ * The gain code is expressed in step * dB (e.g. in 0.1 dB steps):
+ *
+ * G_code = G_dB/step = 20/step*log10(G_linear)
+ *
+ * Inverting the formula, we get
+ *
+ * G_linear = 10^(step/20*G_code) = 2^(log2(10)*step/20*G_code)
+ */
+ return log2_10 * step / 20;
+}
+
class CameraSensorHelperImx219 : public CameraSensorHelper
{
public:
@@ -354,6 +374,17 @@ public:
};
REGISTER_CAMERA_SENSOR_HELPER("imx258", CameraSensorHelperImx258)
+class CameraSensorHelperImx290 : public CameraSensorHelper
+{
+public:
+ CameraSensorHelperImx290()
+ {
+ gainType_ = AnalogueGainExponential;
+ gainConstants_.exp = { 1.0, expGainDb(0.3) };
+ }
+};
+REGISTER_CAMERA_SENSOR_HELPER("imx290", CameraSensorHelperImx290)
+
class CameraSensorHelperOv2740 : public CameraSensorHelper
{
public:
--
Regards,
Laurent Pinchart
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