# coding: utf-8
from time import time
from typing import Tuple, Optional
from numpy import ndarray
import logging
from .meta_camera import Camera
from .._global import OptionalModule
try:
import cv2
except (ModuleNotFoundError, ImportError):
cv2 = OptionalModule("opencv-python")
[docs]
class CameraOpencv(Camera):
"""A class for reading images from any camera able to interface with OpenCV.
The number of the video device to read images from can be specified.
This camera class is less performant than the
:class:`~crappy.camera.CameraGstreamer` one that relies on GStreamer, but the
installation of OpenCV is way easier than the one of GStreamer, especially on
Windows !
Warning:
There are two classes for CameraOpencv, one for Linux based on
`v4l-utils`, and another one for Linux (without `v4l-utils`) and other OS.
Depending on the installation of `v4l-utils` and the OS, the correct class
will be automatically imported. The version using `v4l-utils` allows tuning
more parameters than the basic version.
.. versionadded:: 1.5.9
.. versionchanged:: 2.0.0 renamed from *Camera_opencv* to *CameraOpencv*
"""
[docs]
def __init__(self) -> None:
"""Sets variables and adds the channels setting."""
super().__init__()
self._cap = None
self.add_choice_setting(name="channels",
choices=('1', '3'),
default='1')
[docs]
def open(self, device_num: Optional[int] = 0, **kwargs) -> None:
"""Opens the video stream and sets any user-specified settings.
Args:
device_num: The index of the device to open, as an :obj:`int`.
**kwargs: Any additional setting to set before opening the configuration
window.
"""
# Opening the videocapture device
self.log(logging.INFO, "Opening the image stream from the camera")
self._cap = cv2.VideoCapture(device_num)
min_bright, max_bright = self._get_min_max(cv2.CAP_PROP_BRIGHTNESS)
if min_bright != max_bright:
self.add_scale_setting(name='brightness',
lowest=min_bright,
highest=max_bright,
getter=self._get_brightness,
setter=self._set_brightness)
else:
self.log(logging.INFO, "Could not add Brightness as scale setting,"
"the detected min and max values are identical")
min_cont, max_cont = self._get_min_max(cv2.CAP_PROP_CONTRAST)
if min_cont != max_cont:
self.add_scale_setting(name='contrast',
lowest=min_cont,
highest=max_cont,
getter=self._get_contrast,
setter=self._set_contrast)
else:
self.log(logging.INFO, "Could not add Contrast as scale setting,"
"the detected min and max values are identical")
min_hue, max_hue = self._get_min_max(cv2.CAP_PROP_HUE)
if min_hue != max_hue:
self.add_scale_setting(name='hue',
lowest=min_hue,
highest=max_hue,
getter=self._get_hue,
setter=self._set_hue)
else:
self.log(logging.INFO, "Could not add HUE as scale setting,"
"the detected min and max values are identical")
min_sat, max_sat = self._get_min_max(cv2.CAP_PROP_SATURATION)
if min_sat != max_sat:
self.add_scale_setting(name='saturation',
lowest=min_sat,
highest=max_sat,
getter=self._get_saturation,
setter=self._set_saturation)
else:
self.log(logging.INFO, "Could not add Saturation as scale setting,"
"the detected min and max values are identical")
# Setting the kwargs if any
self.set_all(**kwargs)
[docs]
def get_image(self) -> Tuple[float, ndarray]:
"""Grabs a frame from the videocapture object and returns it along with a
timestamp."""
# Grabbing the frame and the timestamp
t = time()
ret, frame = self._cap.read()
# Checking the integrity of the frame
if not ret:
raise IOError("Error reading the camera")
# Returning the image in the right format, and its timestamp
if self.channels == '1':
return t, cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
else:
return t, frame
[docs]
def close(self) -> None:
"""Releases the videocapture object."""
if self._cap is not None:
self.log(logging.INFO, "Closing the image stream from the camera")
self._cap.release()
def _get_min_max(self, prop_id: int) -> Tuple[int, int]:
"""Gets the min and max values of a parameter."""
self._cap.set(prop_id, 99999)
max_ = int(self._cap.get(prop_id))
self._cap.set(prop_id, -99999)
min_ = int(self._cap.get(prop_id))
if min_ == max_:
self._cap.set(prop_id, 0)
min_ = int(self._cap.get(prop_id))
return min_, max_
def _get_brightness(self) -> int:
"""Gets the image brightness."""
return int(self._cap.get(cv2.CAP_PROP_BRIGHTNESS))
def _get_contrast(self) -> int:
"""Gets the image contrast."""
return int(self._cap.get(cv2.CAP_PROP_CONTRAST))
def _get_hue(self) -> int:
"""Gets the image hue."""
return int(self._cap.get(cv2.CAP_PROP_HUE))
def _get_saturation(self) -> int:
"""Gets the image saturation."""
return int(self._cap.get(cv2.CAP_PROP_SATURATION))
def _set_brightness(self, brightness: int) -> None:
"""Sets the image brightness."""
self._cap.set(cv2.CAP_PROP_BRIGHTNESS, brightness)
def _set_contrast(self, contrast: int) -> None:
"""Sets the image contrast."""
self._cap.set(cv2.CAP_PROP_CONTRAST, contrast)
def _set_hue(self, hue: int) -> None:
"""Sets the image hue."""
self._cap.set(cv2.CAP_PROP_HUE, hue)
def _set_saturation(self, saturation: int) -> None:
"""Sets the image saturation."""
self._cap.set(cv2.CAP_PROP_SATURATION, saturation)