[libcamera-devel] [PATCH v2 1/2] libcamera: camera: Add a mode sensitivity field

[David Plowman]

The modeSensitivity field is a number that describes how sensitive the
selected sensor mode is compared to other readout modes of the same
sensor. For example, a binned mode might have twice the sensitivity of
the full resolution mode, meaning you would get double the signal
level for the same exposure and gains.

Signed-off-by: David Plowman <david.plowman at raspberrypi.com>
---
 include/libcamera/camera.h |  2 ++
 src/libcamera/camera.cpp   | 16 +++++++++++++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/include/libcamera/camera.h b/include/libcamera/camera.h
index 601ee46e..3314c06b 100644
--- a/include/libcamera/camera.h
+++ b/include/libcamera/camera.h
@@ -66,6 +66,8 @@ public:
 
 	Transform transform;
 
+	float modeSensitivity;
+
 protected:
 	CameraConfiguration();
 
diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp
index 71809bcd..8d795dff 100644
--- a/src/libcamera/camera.cpp
+++ b/src/libcamera/camera.cpp
@@ -156,7 +156,7 @@ LOG_DECLARE_CATEGORY(Camera)
  * \brief Create an empty camera configuration
  */
 CameraConfiguration::CameraConfiguration()
-	: transform(Transform::Identity), config_({})
+	: transform(Transform::Identity), modeSensitivity(1.0), config_({})
 {
 }
 
@@ -327,6 +327,20 @@ std::size_t CameraConfiguration::size() const
  * may adjust this field at its discretion if the selection is not supported.
  */
 
+/**
+ * \var CameraConfiguration::modeSensitivity
+ * \brief The relative sensitivity of the chosen sensor mode
+ *
+ * Some sensors have readout modes with different sensitivities. For example,
+ * a binned camera mode might, with the same exposure and gains, produce
+ * twice the signal level of the full resolution readout. This would be
+ * signalled by the binned mode, when it is chosen, indicating a value here
+ * that is twice that of the full resolution mode.
+ *
+ * This value should only be read, and not set, by the user. It will be
+ * valid after the configure method has reteurned successfully.
+ */
+
 /**
  * \var CameraConfiguration::config_
  * \brief The vector of stream configurations
-- 
2.20.1