Reset CCM resets to the CCM in the default tuning file.

src/openflexure_microscope_server/things/camera/picamera.py

@@ -749,9 +749,6 @@ class StreamingPiCamera2(BaseCamera):
 
         It is a 9 value tuple used to specify the 3x3 matrix that the GPU pipeline uses
         to convert from the camera R,G,B vector to the standard R,G,B.
-
-        The value here is interpolated from the IMX219 defaults for the colour temperatures
-        above and below our LED temperature of 5000K.
         """
         return tuple(tf_utils.get_static_ccm(self.tuning)[0]["ccm"])
 
@@ -766,41 +763,14 @@ class StreamingPiCamera2(BaseCamera):
             with self._streaming_picamera(pause_stream=True):
                 self._initialise_picamera()
 
-    # TODO make reset CCM reset from default tuning.
     @lt.thing_action
     def reset_ccm(self) -> None:
-        """Overwrite the colour correction matrix in camera tuning with default values.
-
-        These values are from the Raspberry Pi Camera Algorithm and Tuning Guide, page
-        45.
-        """
-        # This is flattened 3x3 matrix. See `colour_correction_matrix`
-        if self._camera_board == "picamera_v2":
-            col_corr_matrix = [
-                2.222935,
-                -0.759672,
-                -0.463262,
-                -0.683489,
-                2.711882,
-                -1.028399,
-                -0.261375,
-                -0.668016,
-                1.929391,
-            ]
-        else:
-            # Note the only other option is the HQ
-            col_corr_matrix = [
-                2.164374,
-                -0.97259,
-                -0.191778,
-                -0.376957,
-                2.099377,
-                -0.722417,
-                -0.11787,
-                -0.489362,
-                1.607232,
-            ]
-        self.colour_correction_matrix = col_corr_matrix
+        """Overwrite the colour correction matrix in camera tuning with default values."""
+        self.tuning = tf_utils.copy_algo_from_other_tuning(
+            algo="rpi.ccm",
+            base_tuning_file=self.tuning,
+            copy_from=self.default_tuning,
+        )
 
     @lt.thing_action
     def set_static_green_equalisation(self, offset: int = 65535) -> None:
@@ -1018,8 +988,10 @@ class StreamingPiCamera2(BaseCamera):
         by the Raspberry Pi camera.
         """
         with self._streaming_picamera(pause_stream=True):
-            self.tuning = tf_utils.copy_tuning_with_alsc_section_from_other(
-                base_tuning_file=self.tuning, copy_alsc_from=self.default_tuning
+            self.tuning = tf_utils.copy_algo_from_other_tuning(
+                algo="rpi.alsc",
+                base_tuning_file=self.tuning,
+                copy_from=self.default_tuning,
             )
             self._initialise_picamera()
 

src/openflexure_microscope_server/things/camera/picamera_tuning_file_utils.py

@@ -30,8 +30,8 @@ def load_default_tuning(sensor_model: str) -> dict:
     tuning_path = os.path.join(THIS_DIR, "tuning_files", "vc4", fname)
 
     try:
-        with open(tuning_path, "r") as fp:
-            return json.load(fp)
+        with open(tuning_path, "r", encoding="utf-8") as file_obj:
+            return json.load(file_obj)
     except (json.decoder.JSONDecodeError, IOError) as e:
         raise TuningFileError(f"Could not load tuning from {tuning_path}.") from e
 
@@ -165,13 +165,14 @@ def ce_enable_is_static(tuning: dict) -> bool:
     return contrast["ce_enable"] == 0
 
 
-def copy_tuning_with_alsc_section_from_other(
-    *, base_tuning_file: dict, copy_alsc_from: dict
+def copy_algo_from_other_tuning(
+    algo: str, *, base_tuning_file: dict, copy_from: dict
 ) -> dict:
-    """Return a copy of tuning_file with the lens shading correction from another file.
+    """Return a copy of tuning_file with an algorithm copied from another file.
 
-    All parameters are keyword only for clarity.
+    Tuning dict arguments are keyword only for clarity.
 
+    :param algo: The algorithm to copy. Eg ``rpi.alsc`` for lens shading correction.
     :param base_tuning_file: The tuning file to copy.
     :param copy_alsc_from: The tuning file to take the alsc section from.
     :return: A deep copy of base_tuning_file with the alsc section copied in from the
@@ -179,10 +180,10 @@ def copy_tuning_with_alsc_section_from_other(
     """
     output_tuning = deepcopy(base_tuning_file)
     # Find the relevant sub-dict for each tuning file
-    from_i = _index_of_algorithm(copy_alsc_from["algorithms"], "rpi.alsc")
-    to_i = _index_of_algorithm(base_tuning_file["algorithms"], "rpi.alsc")
+    from_i = _index_of_algorithm(copy_from["algorithms"], algo)
+    to_i = _index_of_algorithm(base_tuning_file["algorithms"], algo)
     # Updating the dictionary in place.
-    output_tuning["algorithms"][to_i] = deepcopy(copy_alsc_from["algorithms"][from_i])
+    output_tuning["algorithms"][to_i] = deepcopy(copy_from["algorithms"][from_i])
     return output_tuning