add tifffile backend support for image io (#868)

* add tifffile backend support for imageio

* add tifffile package for test requirements

* add tifffile package for test requirements

* small tiffile

mmcv/image/io.py

@@ -19,8 +19,13 @@
 except ImportError:
     Image = None
 
+try:
+    import tifffile
+except ImportError:
+    tifffile = None
+
 jpeg = None
-supported_backends = ['cv2', 'turbojpeg', 'pillow']
+supported_backends = ['cv2', 'turbojpeg', 'pillow', 'tifffile']
 
 imread_flags = {
     'color': IMREAD_COLOR,
@@ -36,8 +41,9 @@ def use_backend(backend):
 
     Args:
         backend (str): The image decoding backend type. Options are `cv2`,
-        `pillow`, `turbojpeg` (see https://github.com/lilohuang/PyTurboJPEG).
-        `turbojpeg` is faster but it only supports `.jpeg` file format.
+        `pillow`, `turbojpeg` (see https://github.com/lilohuang/PyTurboJPEG)
+        and `tifffile`. `turbojpeg` is faster but it only supports `.jpeg`
+        file format.
     """
     assert backend in supported_backends
     global imread_backend
@@ -51,6 +57,9 @@ def use_backend(backend):
     elif imread_backend == 'pillow':
         if Image is None:
             raise ImportError('`Pillow` is not installed')
+    elif imread_backend == 'tifffile':
+        if tifffile is None:
+            raise ImportError('`tifffile` is not installed')
 
 
 def _jpegflag(flag='color', channel_order='bgr'):
@@ -134,9 +143,9 @@ def imread(img_or_path, flag='color', channel_order='bgr', backend=None):
             Note that the `turbojpeg` backened does not support `unchanged`.
         channel_order (str): Order of channel, candidates are `bgr` and `rgb`.
         backend (str | None): The image decoding backend type. Options are
-            `cv2`, `pillow`, `turbojpeg`, `None`. If backend is None, the
-            global imread_backend specified by ``mmcv.use_backend()`` will be
-            used. Default: None.
+            `cv2`, `pillow`, `turbojpeg`, `tifffile`, `None`.
+            If backend is None, the global imread_backend specified by
+            ``mmcv.use_backend()`` will be used. Default: None.
 
     Returns:
         ndarray: Loaded image array.
@@ -166,6 +175,9 @@ def imread(img_or_path, flag='color', channel_order='bgr', backend=None):
             img = Image.open(img_or_path)
             img = _pillow2array(img, flag, channel_order)
             return img
+        elif backend == 'tifffile':
+            img = tifffile.imread(img_or_path)
+            return img
         else:
             flag = imread_flags[flag] if is_str(flag) else flag
             img = cv2.imread(img_or_path, flag)

requirements/test.txt

@@ -5,3 +5,4 @@ onnxoptimizer
 onnxruntime==1.4.0
 pytest
 PyTurboJPEG
+tiffile

tests/test_image/test_io.py

@@ -28,6 +28,7 @@ def setup_class(cls):
         cls.palette_img_path = osp.join(cls.data_dir, 'palette.gif')
         cls.exif_img_path = osp.join(cls.data_dir, 'color_exif.jpg')
         cls.img = cv2.imread(cls.img_path)
+        cls.tiff_path = osp.join(cls.data_dir, 'uint16-5channel.tif')
 
     def assert_img_equal(self, img, ref_img, ratio_thr=0.999):
         assert img.shape == ref_img.shape
@@ -173,6 +174,11 @@ def test_imread(self):
         with pytest.raises(ValueError):
             mmcv.imread(self.img_path, 'unsupported_backend')
 
+        # backend tifffile, multi channel tiff file(> 4 channels).
+        mmcv.use_backend('tifffile')
+        img_tifffile = mmcv.imread(self.tiff_path)
+        assert img_tifffile.shape == (200, 150, 5)
+
         mmcv.use_backend('cv2')
 
         # consistent exif behaviour