Test Image._repr_png_

skimage/io/tests/test_image.py

@@ -1,7 +1,12 @@
-from skimage.io import Image
+from io import BytesIO
+
+import numpy as np
+from skimage import img_as_ubyte
+from skimage.io import Image, imread
 
 from numpy.testing import assert_equal, assert_array_equal
 
+
 def test_tags():
     f = Image([1, 2, 3], foo='bar', sigma='delta')
     g = Image([3, 2, 1], sun='moon')
@@ -11,7 +16,17 @@ def test_tags():
     assert_array_equal((g + 2).tags['sun'], 'moon')
     assert_equal(h.tags, {})
 
+
+def test_repr_png_roundtrip():
+    original_array = 255 * np.ones((3, 3), dtype=np.uint8)
+    image = Image(original_array)
+    array = imread(BytesIO(image._repr_png_()))
+    # Force output to ubyte range for plugin compatibility.
+    # For example, Matplotlib will return floats even if the image is uint8.
+    assert_array_equal(img_as_ubyte(array), original_array)
+    # Note that PIL breaks with `_repr_jpeg_`.
+
+
 if __name__ == "__main__":
     from numpy.testing import run_module_suite
     run_module_suite()
-