add `pil` backend for DecodeImage

ppcls/data/preprocess/ops/operators.py

@@ -18,6 +18,7 @@ from __future__ import print_function
 from __future__ import unicode_literals
 
 from functools import partial
+import io
 import six
 import math
 import random
@@ -93,11 +94,22 @@ class OperatorParamError(ValueError):
 class DecodeImage(object):
     """ decode image """
 
-    def __init__(self, to_rgb=True, to_np=False, channel_first=False):
+    def __init__(self,
+                 to_rgb=True,
+                 to_np=False,
+                 channel_first=False,
+                 backend="cv2"):
         self.to_rgb = to_rgb
         self.to_np = to_np  # to numpy
         self.channel_first = channel_first  # only enabled when to_np is True
 
+        if backend.lower() not in ["cv2", "pil"]:
+            logger.warning(
+                f"The backend of Resize only support \"cv2\" or \"PIL\". \"f{backend}\" is unavailable. Use \"cv2\" instead."
+            )
+            backend = "cv2"
+        self.backend = backend.lower()
+
     def __call__(self, img):
         if six.PY2:
             assert type(img) is str and len(
@@ -105,8 +117,15 @@ class DecodeImage(object):
         else:
             assert type(img) is bytes and len(
                 img) > 0, "invalid input 'img' in DecodeImage"
+
+        if self.backend == "pil":
+            data = io.BytesIO(img)
+            img = Image.open(data).convert("RGB")
+            img = np.asarray(img)[:, :, ::-1]  # to bgr
+        else:
             data = np.frombuffer(img, dtype='uint8')
             img = cv2.imdecode(data, 1)
+
         if self.to_rgb:
             assert img.shape[2] == 3, 'invalid shape of image[%s]' % (
                 img.shape)