!9920 python eager add decode

From: @luoyang42
Reviewed-by: @liucunwei
Signed-off-by: @liucunwei

mindspore/dataset/vision/c_transforms.py

@@ -175,6 +175,22 @@ class Decode(cde.DecodeOp):
         self.rgb = rgb
         super().__init__(self.rgb)
 
+    def __call__(self, img):
+        """
+        Call method.
+
+        Args:
+            img (NumPy): Image to be decoded.
+
+        Returns:
+            img (NumPy), Decoded image.
+        """
+        if not isinstance(img, np.ndarray) or img.ndim != 1 or img.dtype.type is np.str_:
+            raise TypeError("Input should be a 1-D NumPy with integer type, got {}.".format(type(img)))
+        decode = cde.Execute(cde.DecodeOp(self.rgb))
+        img = decode(cde.Tensor(np.asarray(img)))
+        return img.as_array()
+
 
 class CutMixBatch(cde.CutMixBatchOp):
     """

tests/ut/python/dataset/test_eager_vision.py

@@ -13,10 +13,22 @@
 # limitations under the License.
 # ==============================================================================
 import cv2
+import numpy as np
 from PIL import Image
 import mindspore.dataset.vision.c_transforms as C
 from mindspore import log as logger
 
+
+def test_eager_decode():
+    img = np.fromfile("../data/dataset/apple.jpg", dtype=np.uint8)
+    logger.info("Image.type: {}, Image.shape: {}".format(type(img), img.shape))
+
+    img = C.Decode()(img)
+    logger.info("Image.type: {}, Image.shape: {}".format(type(img), img.shape))
+
+    assert img.shape == (2268, 4032, 3)
+
+
 def test_eager_resize():
     img = cv2.imread("../data/dataset/apple.jpg")
     logger.info("Image.type: {}, Image.shape: {}".format(type(img), img.shape))
@@ -78,6 +90,20 @@ def test_eager_pad():
     assert size_padded == (size[0] + 2 * pad, size[1] + 2 * pad, size[2])
 
 def test_eager_exceptions():
+    try:
+        img = "../data/dataset/apple.jpg"
+        img = C.Decode()(img)
+        assert False
+    except TypeError as e:
+        assert "Input should be a 1-D NumPy with integer type" in str(e)
+
+    try:
+        img = np.array(["a", "b", "c"])
+        img = C.Decode()(img)
+        assert False
+    except TypeError as e:
+        assert "Input should be a 1-D NumPy with integer type" in str(e)
+
     try:
         img = cv2.imread("../data/dataset/apple.jpg")
         img = C.Resize(size=(-32, 32))(img)
@@ -94,6 +120,7 @@ def test_eager_exceptions():
 
 
 if __name__ == '__main__':
+    test_eager_decode()
     test_eager_resize()
     test_eager_rescale()
     test_eager_normalize()