Fixed description and linted

openflexure_microscope/api/default_extensions/picamera_autocalibrate/extension.py

@@ -2,8 +2,6 @@ import logging
 from contextlib import contextmanager
 
 import labthings.fields as fields
-import numpy as np
-import picamerax
 from flask import abort
 from labthings import find_component
 from labthings.extensions import BaseExtension
@@ -13,12 +11,10 @@ from openflexure_microscope.camera.base import BaseCamera
 from openflexure_microscope.microscope import Microscope
 
 from .recalibrate_utils import (
-    auto_expose_and_freeze_settings,
-    flat_lens_shading_table,
-    get_channel_percentiles,
-    recalibrate_camera,
     adjust_shutter_and_gain_from_raw,
     adjust_white_balance_from_raw,
+    flat_lens_shading_table,
+    get_channel_percentiles,
     lst_from_camera,
 )
 
@@ -82,11 +78,9 @@ class LSTExtension(BaseExtension):
             "/auto_white_balance_from_raw",
             endpoint="auto_white_balance_from_raw",
         )
-        
-                
 
 
-def find_microscope():
+def find_microscope() -> Microscope:
     """Locate the microscope and raise a sensible error if it's missing."""
     microscope = find_component("org.openflexure.microscope")
 
@@ -96,9 +90,7 @@ def find_microscope():
         )
 
     if not hasattr(microscope.camera, "picamera"):
-        abort(
-            503, "The PiCamera calibration plugin requires a Raspberry Pi camera."
-        )
+        abort(503, "The PiCamera calibration plugin requires a Raspberry Pi camera.")
 
     return microscope
 
@@ -106,10 +98,15 @@ def find_microscope():
 class RecalibrateView(ActionView):
     args = {
         "skip_auto_exposure": fields.Bool(
-            missing=False, 
-            description="Whether to "
+            missing=False,
+            description=(
+                "By default we perform an auto-exposure and AWB "
+                "step before updating the lens shading table.  Set "
+                "this argument to True to disable those steps."
+            ),
         )
     }
+
     def post(self, args):
         """Reset the camera's settings.
 
@@ -184,8 +181,7 @@ class AutoExposureFromRawView(ActionView):
     def post(self, args):
         camera = find_component("org.openflexure.microscope").camera.picamera
         adjust_shutter_and_gain_from_raw(
-            camera,
-            **args  # I'm relying on the schema to fill in missing values
+            camera, **args  # I'm relying on the schema to fill in missing values
         )
 
 
@@ -206,8 +202,7 @@ class AutoWhiteBalanceFromRawView(ActionView):
     def post(self, args):
         camera = find_component("org.openflexure.microscope").camera.picamera
         adjust_white_balance_from_raw(
-            camera,
-            **args  # I'm relying on the schema to fill in missing values
+            camera, **args  # I'm relying on the schema to fill in missing values
         )
 
 

openflexure_microscope/api/default_extensions/picamera_autocalibrate/recalibrate_utils.py

@@ -7,6 +7,12 @@ import numpy as np
 from picamerax import PiCamera
 from picamerax.array import PiBayerArray, PiRGBArray
 
+# I have used f strings throughout, for readability.
+# The performance implication of using them in logging statements
+# really doesn't matter here - also, loglevel is usually set to
+# INFO to report progress via the LabThings action API
+# pylint: disable=logging-fstring-interpolation
+
 
 def rgb_image(
     camera: PiCamera, resize: Optional[Tuple[int, int]] = None, **kwargs
@@ -66,6 +72,12 @@ def adjust_exposure_and_gain(
     iterations = 0
     while True:
         iterations += 1
+        if iterations > max_iterations:
+            logging.warning(
+                f"Auto exposure is stopping after {max_iterations} "
+                "but it has not converged."
+            )
+            break
 
         with PiBayerArray(camera) as a:
             camera.capture(a, format="jpeg", bayer=True)
@@ -86,7 +98,7 @@ def adjust_exposure_and_gain(
             f"{previous_shutter_speed} to {current_shutter_speed}"
         )
         if current_shutter_speed == previous_shutter_speed:
-            logging.info(f"Shutter speed has saturated, stopping.")
+            logging.info("Shutter speed has saturated, stopping.")
             break
 
     if max_brightness > target_white_level:
@@ -153,7 +165,6 @@ def adjust_shutter_and_gain_from_raw(
     # until either the brightness is high enough, or we can't increase the
     # shutter speed any more.
     iterations = 0
-    shutter_speed_maximised = False
     shutter_speed_increments = [10, 2, None]
     shutter_speed_increment = shutter_speed_increments.pop(0)
     while iterations < max_iterations:
@@ -202,14 +213,9 @@ def adjust_shutter_and_gain_from_raw(
         if current_shutter_speed == tested_shutter_speed:
             camera.analog_gain *= 2
             if camera.analog_gain == tested_analog_gain:
-                logging.info(f"Shutter speed and gain are both maxed out.  Giving up!")
+                logging.info("Shutter speed and gain are both maxed out.  Giving up!")
                 break
-            logging.info(
-                f"Shutter speed has maxed out at {current_shutter_speed}, doubled gain."
-            )
-
-    max_brightness = np.max(get_channel_percentiles(camera, percentile))
-    logging.info(f"Brightness {max_brightness} after {iterations} tries.")
+            logging.info("Shutter speed has maxed out, doubled gain to compensate.")
     return max_brightness
 
 
@@ -330,6 +336,7 @@ def lst_from_channels(channels: np.ndarray) -> np.ndarray:
     lens_shading_table: np.ndarray = gains.astype(np.uint8)
     return lens_shading_table[::-1, :, :].copy()
 
+
 def lst_from_camera(camera: PiCamera) -> np.ndarray:
     """Acquire a raw image and use it to calculate a lens shading table."""
     with PiBayerArray(camera) as a:
@@ -343,6 +350,7 @@ def lst_from_camera(camera: PiCamera) -> np.ndarray:
     channels = channels_from_bayer_array(raw_image)
     return lst_from_channels(channels)
 
+
 def recalibrate_camera(camera: PiCamera):
     """Reset the lens shading table and exposure settings.