OpenCV is now an optional dependency

Should contribute fixing Issue #99

Author: PierreRaybaut

cdl/algorithms/image.py

@@ -10,7 +10,6 @@
 
 from typing import Literal
 
-import cv2
 import numpy as np
 import scipy.ndimage as spi
 import scipy.spatial as spt
@@ -720,6 +719,14 @@ def find_blobs_opencv(
     Returns:
         Coordinates of blobs
     """
+
+    # Note:
+    # Importing OpenCV inside the function in order to eventually raise an ImportError
+    # when the function is called and OpenCV is not installed. This error will be
+    # handled by DataLab and the user will be informed that OpenCV is required to use
+    # this function.
+    import cv2  # pylint: disable=import-outside-toplevel
+
     params = cv2.SimpleBlobDetector_Params()
     if min_threshold is not None:
         params.minThreshold = min_threshold

cdl/tests/conftest.py

@@ -10,7 +10,6 @@
 
 import os
 
-import cv2
 import guidata
 import h5py
 import numpy
@@ -47,9 +46,14 @@ def pytest_report_header(config):  # pylint: disable=unused-argument
         f"PythonQwt {qwt.__version__}, "
         f"{qtpy.API_NAME} {qtbindings_version} [Qt version: {qtpy.QT_VERSION}]",
         f"NumPy {numpy.__version__}, SciPy {scipy.__version__}, "
-        f"h5py {h5py.__version__}, "
-        f"scikit-image {skimage.__version__}, OpenCV {cv2.__version__}",
+        f"h5py {h5py.__version__}, scikit-image {skimage.__version__}",
     ]
+    try:
+        import cv2  # pylint: disable=import-outside-toplevel
+
+        infolist.append(f", OpenCV {cv2.__version__}")
+    except ImportError:
+        pass
     for vname in ("CDL_DATA", "PYTHONPATH", "DEBUG"):
         value = os.environ.get(vname, "")
         if value:

pyproject.toml

@@ -44,7 +44,6 @@ dependencies = [
     "NumPy >= 1.21",
     "SciPy >= 1.7",
     "scikit-image >= 0.18",
-    "opencv-python-headless >= 4.5",
     "pandas >= 1.3",
     "PyWavelets >= 1.1",
     "psutil >= 5.5",
@@ -65,6 +64,7 @@ cdl-tests = "cdl.tests:run"
 
 [project.optional-dependencies]
 qt = ["PyQt5"]
+opencv = ["opencv-python-headless >= 4.5"]
 dev = ["ruff", "pylint", "Coverage", "pyinstaller>=6.0"]
 doc = [
     "PyQt5",