Refactor image reading in iread function to use cv.imdecode for better compatibility; add unit tests for iread functionality.

Author: petercorke

src/machinevisiontoolbox/base/imageio.py

@@ -830,7 +830,10 @@ def iread(filename, *args, **kwargs):
             images = []
             pathlist.sort()
             for p in pathlist:
-                image = cv.imread(p, -1)  # default read-in as BGR
+                image = cv.imdecode(
+                    np.fromfile(Path(p).as_posix(), dtype=np.uint8), cv.IMREAD_UNCHANGED
+                )
+                # image = cv.imread(p, -1)  # default read-in as BGR
                 images.append(convert(image, **kwargs))
             return images, pathlist
 
@@ -840,6 +843,9 @@ def iread(filename, *args, **kwargs):
 
             # read the image
             # TODO not sure the following will work on Windows
+            image = cv.imdecode(
+                np.fromfile(path.as_posix(), dtype=np.uint8), cv.IMREAD_UNCHANGED
+            )
             image = cv.imread(path.as_posix(), -1)  # default read-in as BGR
             if image is None:
                 # TODO check ValueError

tests/base/test_io.py

@@ -0,0 +1,76 @@
+#!/usr/bin/env python
+
+# test for Image input/output
+
+import numpy as np
+import os
+import numpy.testing as nt
+import unittest
+import contextlib
+import io
+
+# import machinevisiontoolbox as mvt
+from machinevisiontoolbox import Image, ImageCollection
+from machinevisiontoolbox.base import iread
+from pathlib import Path
+from collections.abc import Iterable
+
+
+class TestBaseImageIO(unittest.TestCase):
+
+    def test_iread(self):
+        # greyscale image
+        im = iread("wally.png")
+        self.assertIsInstance(im[0], np.ndarray)
+        self.assertIsInstance(im[1], str)
+        self.assertEqual(im[0].shape, (25, 21))
+
+        # color image
+        im = iread("monalisa.png")
+        self.assertIsInstance(im[0], np.ndarray)
+        self.assertIsInstance(im[1], str)
+        self.assertEqual(im[0].shape, (700, 677, 3))
+
+        # greyscale image sequence
+        im = iread("seq/im*.png")
+        self.assertIsInstance(im[0], list)
+        self.assertEqual(len(im[0]), 9)
+        self.assertIsInstance(im[0][0], np.ndarray)
+        self.assertEqual(im[0][0].shape, (512, 512), self.assertIsInstance(im[1], list))
+        self.assertEqual(len(im[1]), 9)
+        self.assertIsInstance(im[1][0], str)
+
+        # color image sequence
+        im = iread("campus/holdout/*.png")
+        self.assertIsInstance(im[0], list)
+        self.assertEqual(len(im[0]), 5)
+        self.assertIsInstance(im[0][0], np.ndarray)
+        self.assertEqual(im[0][0].shape, (426, 640, 3))
+        self.assertIsInstance(im[1], list)
+        self.assertEqual(len(im[1]), 5)
+        self.assertIsInstance(im[1][0], str)
+
+        # URL image
+        im = iread("https://petercorke.com/files/images/monalisa.png")
+        self.assertIsInstance(im[0], np.ndarray)
+        self.assertIsInstance(im[1], str)
+        self.assertEqual(im[0].shape, (700, 677, 3))
+
+    # TODO unit tests:
+    # test the various options to iread()
+    # test writing
+    # test_isimage - make sure Image rejects/fails with invalid input
+    # test_imtypes - test Image works on different Image types?
+    # test_getimage - make sure Image returns the same array but with valid
+    # typing?
+    # test_imwrite - test write/successfully save file?
+
+    def tearDown(self):
+        # Cleanup code if needed
+        pass
+
+
+# ------------------------------------------------------------------------ #
+if __name__ == "__main__":
+
+    unittest.main()

tests/test_image_io.py

@@ -18,19 +18,6 @@
 
 class TestImage(unittest.TestCase):
 
-    def test_iread(self):
-        # see ioTest.m
-        # test image:
-        im = iread("wally.png")
-        self.assertIsInstance(im[0], np.ndarray)
-        self.assertIsInstance(im[1], str)
-        self.assertEqual(im[0].shape, (25, 21))
-
-        im = iread("monalisa.png")
-        self.assertIsInstance(im[0], np.ndarray)
-        self.assertIsInstance(im[1], str)
-        self.assertEqual(im[0].shape, (700, 677, 3))
-
     def test_isimage(self):
 
         # create mini image (Bayer pattern)