Add imresize API to docs

docs/api/python/image/image.md

@@ -17,6 +17,7 @@ images provided in
     :nosignatures:
 
     image.imdecode
+    image.imresize
     image.scale_down
     image.resize_short
     image.fixed_crop
@@ -164,6 +165,7 @@ and a list of augmenters specific for `Object detection` is provided
     :members:
 
 .. automethod:: mxnet.image.imdecode
+.. automethod:: mxnet.image.imresize
 .. automethod:: mxnet.image.scale_down
 .. automethod:: mxnet.image.resize_short
 .. automethod:: mxnet.image.fixed_crop

python/mxnet/image/image.py

@@ -38,7 +38,6 @@
 from ..base import numeric_types
 from .. import ndarray as nd
 from ..ndarray import _internal
-from ..ndarray._internal import _cvimresize as imresize
 from ..ndarray._internal import _cvcopyMakeBorder as copyMakeBorder
 from .. import io
 from .. import recordio
@@ -85,6 +84,46 @@ def imread(filename, *args, **kwargs):
     return _internal._cvimread(filename, *args, **kwargs)
 
 
+def imresize(src, w, h, interp):
+    r"""Resize image with OpenCV.
+
+    Note: `imread` uses OpenCV (not the CV2 Python library).
+    MXNet must have been built with USE_OPENCV=1 for `imdecode` to work.
+
+    Parameters
+    ----------
+    src : NDArray
+        source image
+    w : int, required
+        Width of resized image.
+    h : int, required
+        Height of resized image.
+    interp : int, optional, default='1'
+        Interpolation method (default=cv2.INTER_LINEAR).
+
+    out : NDArray, optional
+        The output NDArray to hold the result.
+
+    Returns
+    -------
+    out : NDArray or list of NDArrays
+        The output of this function.
+
+    Example
+    -------
+    >>> with open("flower.jpeg", 'rb') as fp:
+    ...     str_image = fp.read()
+    ...
+    >>> image = mx.img.imdecode(str_image)
+    >>> image
+    <NDArray 2321x3482x3 @cpu(0)>
+    >>> new_image = mx.img.resize(image, 240, 360)
+    >>> new_image
+    <NDArray 2321x3482x3 @cpu(0)>
+    """
+    return _internal._cvimresize(src, w, h, interp)
+
+
 def imdecode(buf, *args, **kwargs):
     """Decode an image to an NDArray.
 

tests/python/unittest/test_image.py

@@ -118,6 +118,22 @@ def test_resize_short(self):
                     mx_resized = mx.image.resize_short(mx_img, new_size, interp)
                     assert_almost_equal(mx_resized.asnumpy()[:, :, (2, 1, 0)], cv_resized, atol=3)
 
+    def test_imresize(self):
+        try:
+            import cv2
+        except ImportError:
+            return
+        for img in TestImage.IMAGES:
+            cv_img = cv2.imread(img)
+            mx_img = mx.nd.array(cv_img[:, :, (2, 1, 0)])
+            for _ in range(3):
+                new_h = np.random.randint(1, 1000)
+                new_w = np.random.randint(1, 1000)
+                for interp in range(0, 2):
+                    cv_resized = cv2.resize(cv_img, (new_w, new_h), interpolation=interp)
+                    mx_resized = mx.image.imresize(mx_img, new_w, new_h, interp)
+                    assert_almost_equal(mx_resized.asnumpy()[:, :, (2, 1, 0)], cv_resized, atol=3)
+
     def test_color_normalize(self):
         for _ in range(10):
             mean = np.random.rand(3) * 255