BUG: Fix image_from_array to handle non-contiguous arrays

The issue was that GetImageViewFromArray always reversed the shape for
non-vector images, regardless of whether the array was C-contiguous or
F-contiguous. However, the C++ code reverses the shape again for F-contiguous
arrays, resulting in a double reversal.

The fix: Only reverse the shape in Python for C-contiguous arrays. For
F-contiguous arrays, pass the shape as-is to C++, which will handle the
reversal there.

Added comprehensive test cases for both image_from_array and
image_view_from_array with transposed arrays.

Co-authored-by: thewtex <25432+thewtex@users.noreply.github.com>

Author: 2 people

Modules/Bridge/NumPy/wrapping/PyBuffer.i.in

@@ -103,7 +103,10 @@
             else:
                 imgview = itkPyBuffer@PyBufferTypes@._get_image_view_from_contiguous_array(ndarr, ndarr.shape[-1:0:-1], ndarr.shape[0])
         else:
-            imgview = itkPyBuffer@PyBufferTypes@._get_image_view_from_contiguous_array(ndarr, ndarr.shape[::-1], 1)
+            if ndarr.flags['C_CONTIGUOUS']:
+                imgview = itkPyBuffer@PyBufferTypes@._get_image_view_from_contiguous_array(ndarr, ndarr.shape[::-1], 1)
+            else:
+                imgview = itkPyBuffer@PyBufferTypes@._get_image_view_from_contiguous_array(ndarr, ndarr.shape, 1)
 
         # Keep a reference
         imgview._SetBase(ndarr)

Wrapping/Generators/Python/Tests/extras.py

@@ -418,6 +418,24 @@ def custom_callback(name, progress):
 arr_fortran = arr.copy(order="F")
 image = itk.GetImageViewFromArray(arr_fortran)
 assert np.array_equal(arr_fortran.shape, image.shape)
+# Test that image_from_array handles array.T correctly (F-contiguous arrays)
+test_arr = np.empty((1, 2, 3))
+image_from_arr = itk.image_from_array(test_arr)
+image_from_transpose = itk.image_from_array(test_arr.T)
+image_from_transpose_copy = itk.image_from_array(test_arr.T.copy())
+assert np.array_equal(image_from_arr.shape, test_arr.shape), \
+    f"Expected shape {test_arr.shape}, got {image_from_arr.shape}"
+assert np.array_equal(image_from_transpose.shape, test_arr.T.shape), \
+    f"Expected shape {test_arr.T.shape}, got {image_from_transpose.shape}"
+assert np.array_equal(image_from_transpose_copy.shape, test_arr.T.shape), \
+    f"Expected shape {test_arr.T.shape}, got {image_from_transpose_copy.shape}"
+# Also verify with image_view_from_array for consistency
+image_view_from_arr = itk.image_view_from_array(test_arr)
+image_view_from_transpose = itk.image_view_from_array(test_arr.T)
+assert np.array_equal(image_view_from_arr.shape, test_arr.shape), \
+    f"Expected shape {test_arr.shape}, got {image_view_from_arr.shape}"
+assert np.array_equal(image_view_from_transpose.shape, test_arr.T.shape), \
+    f"Expected shape {test_arr.T.shape}, got {image_view_from_transpose.shape}"
 image = itk.image_from_array(arr, is_vector=True)
 assert image.GetImageDimension() == 2
 image = itk.GetImageViewFromArray(arr, is_vector=True)