Fix auto-exposure and AWB
The previous "auto calibrate" button for the camera relied on a combination of the built-in autoexposure/AWB and some JPEG-based tweaks to get the exposure settings right. This often led to confusing results, e.g. oscillating between green and pink images. I have rewritten the auto-exposure code to adjust gain and shutter speed based on the raw image. This seems to be very reliable, at the expense of being quite slow. That's a price I'm happy to pay. I have replaced both the camera's auto white balance and my JPEG-based AWB hack with a single-shot AWB method that looks at the raw image.
This commit is contained in:
Richard Bowman
parent
864e4c9c41
commit
5527c4eb7b
2 changed files with 320 additions and 50 deletions
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@ -1,6 +1,8 @@
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import logging
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from contextlib import contextmanager
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import labthings.fields as fields
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import numpy as np
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import picamerax
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from flask import abort
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from labthings import find_component
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@ -13,7 +15,11 @@ from openflexure_microscope.microscope import Microscope
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from .recalibrate_utils import (
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auto_expose_and_freeze_settings,
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flat_lens_shading_table,
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get_channel_percentiles,
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recalibrate_camera,
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adjust_shutter_and_gain_from_raw,
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adjust_white_balance_from_raw,
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lst_from_camera,
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)
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@ -61,48 +67,71 @@ class LSTExtension(BaseExtension):
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"/delete_lens_shading_table",
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endpoint="delete_lens_shading_table",
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)
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self.add_view(
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GetRawChannelPercentilesView,
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"/get_raw_channel_percentiles",
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endpoint="get_raw_channel_percentiles",
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)
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self.add_view(
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AutoExposureFromRawView,
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"/auto_exposure_from_raw",
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endpoint="auto_exposure_from_raw",
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)
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self.add_view(
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AutoWhiteBalanceFromRawView,
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"/auto_white_balance_from_raw",
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endpoint="auto_white_balance_from_raw",
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)
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def recalibrate(self, microscope: Microscope):
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def find_microscope():
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"""Locate the microscope and raise a sensible error if it's missing."""
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microscope = find_component("org.openflexure.microscope")
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if not microscope:
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abort(
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503, "No microscope connected. Unable to use camera calibration functions."
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)
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if not hasattr(microscope.camera, "picamera"):
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abort(
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503, "The PiCamera calibration plugin requires a Raspberry Pi camera."
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)
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return microscope
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class RecalibrateView(ActionView):
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args = {
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"skip_auto_exposure": fields.Bool(
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missing=False,
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description="Whether to "
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)
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}
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def post(self, args):
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"""Reset the camera's settings.
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This generates new gains, exposure time, and lens shading
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table such that the background is as uniform as possible
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with a gray level of 230. It takes a little while to run.
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"""
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with pause_stream(microscope.camera) as scamera:
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if hasattr(scamera, "picamera"):
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picamera_obj: picamerax.PiCamera = getattr(scamera, "picamera")
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auto_expose_and_freeze_settings(picamera_obj)
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recalibrate_camera(picamera_obj)
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microscope.save_settings()
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else:
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raise RuntimeError(
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"Recalibrate can only be used with a Raspberry Pi camera"
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)
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class RecalibrateView(ActionView):
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def post(self):
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microscope = find_component("org.openflexure.microscope")
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if not microscope:
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abort(503, "No microscope connected. Unable to recalibrate.")
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microscope = find_microscope()
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logging.info("Starting microscope recalibration...")
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return self.extension.recalibrate(microscope)
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picamera = microscope.camera.picamera
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if not args.get("skip_auto_exposure"):
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adjust_shutter_and_gain_from_raw(picamera)
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adjust_white_balance_from_raw(picamera)
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lst = lst_from_camera(picamera)
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with pause_stream(microscope.camera) as scamera:
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scamera.picamera.lens_shading_table = lst
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microscope.save_settings()
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class FlattenLSTView(ActionView):
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def post(self):
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microscope = find_component("org.openflexure.microscope")
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if not microscope:
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abort(
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503,
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"No microscope connected. Unable to flatten the lens shading table.",
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)
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microscope = find_microscope()
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with pause_stream(microscope.camera) as scamera:
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flat_lst = flat_lens_shading_table(scamera.camera)
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scamera.camera.lens_shading_table = flat_lst
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@ -111,14 +140,86 @@ class FlattenLSTView(ActionView):
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class DeleteLSTView(ActionView):
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def post(self):
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microscope = find_component("org.openflexure.microscope")
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if not microscope:
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abort(
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503,
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"No microscope connected. Unable to flatten the lens shading table.",
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)
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microscope = find_microscope()
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with pause_stream(microscope.camera) as scamera:
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scamera.camera.lens_shading_table = None
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microscope.save_settings()
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class AutoExposureFromRawView(ActionView):
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args = {
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"target_white_level": fields.Int(
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missing=700,
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example=700,
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description=(
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"The pixel value (10-bit format) that we aim for when adjusting shutter/gain."
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),
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),
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"max_iterations": fields.Int(
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missing=20,
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description=(
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"The number of adjustments to the camera's settings to make before giving up."
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),
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),
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"tolerance": fields.Float(
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missing=0.05,
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example=0.05,
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description=(
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"We stop adjusting when we get within this fraction of the target "
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"value. It is a number between 0 and 1, usually 0.01--0.1."
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),
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),
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"percentile": fields.Float(
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missing=99.9,
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example=99.9,
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description=(
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"A float between 0 and 100 setting the centile to use "
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"to measure the white point of the image. A value "
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"of 99.9 allows 0.1% of the pixels to be erroneously "
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"bright - this helps stability in low light."
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),
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),
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}
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def post(self, args):
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camera = find_component("org.openflexure.microscope").camera.picamera
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adjust_shutter_and_gain_from_raw(
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camera,
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**args # I'm relying on the schema to fill in missing values
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)
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class AutoWhiteBalanceFromRawView(ActionView):
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args = {
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"percentile": fields.Float(
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missing=99.9,
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example=99.9,
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description=(
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"A float between 0 and 100 setting the centile to use "
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"to measure the white point of the image. A value "
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"of 99.9 allows 0.1% of the pixels to be erroneously "
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"bright - this helps stability in low light."
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),
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)
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}
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def post(self, args):
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camera = find_component("org.openflexure.microscope").camera.picamera
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adjust_white_balance_from_raw(
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camera,
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**args # I'm relying on the schema to fill in missing values
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)
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class GetRawChannelPercentilesView(ActionView):
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args = {
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"percentile": fields.Float(
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example=99.9,
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description="A float between 0 and 100 setting the centile to calculate",
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)
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}
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schema = fields.List(fields.Integer)
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def post(self, args):
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camera = find_component("org.openflexure.microscope").camera.picamera
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return get_channel_percentiles(camera, args["percentile"])
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