fix python dependency for voc2012 dataset

python/paddle/v2/dataset/voc_seg.py

@@ -22,7 +22,7 @@ with segmentation has been increased from 7,062 to 9,993.
 import tarfile
 import io
 import numpy as np
-from common import download
+from paddle.v2.dataset.common import download
 from paddle.v2.image import *
 from PIL import Image
 
@@ -36,6 +36,8 @@ SET_FILE = 'VOCdevkit/VOC2012/ImageSets/Segmentation/{}.txt'
 DATA_FILE = 'VOCdevkit/VOC2012/JPEGImages/{}.jpg'
 LABEL_FILE = 'VOCdevkit/VOC2012/SegmentationClass/{}.png'
 
+CACHE_DIR = 'voc2012'
+
 
 def reader_creator(filename, sub_name):
 
@@ -66,18 +68,18 @@ def train():
     """
     Create a train dataset reader containing 2913 images in HWC order.
     """
-    return reader_creator(download(VOC_URL, 'voc_seg', VOC_MD5), 'trainval')
+    return reader_creator(download(VOC_URL, CACHE_DIR, VOC_MD5), 'trainval')
 
 
 def test():
     """
     Create a test dataset reader containing 1464 images in HWC order.
     """
-    return reader_creator(download(VOC_URL, 'voc_seg', VOC_MD5), 'train')
+    return reader_creator(download(VOC_URL, CACHE_DIR, VOC_MD5), 'train')
 
 
 def val():
     """
     Create a val dataset reader containing 1449 images in HWC order.
     """
-    return reader_creator(download(VOC_URL, 'voc_seg', VOC_MD5), 'val')
+    return reader_creator(download(VOC_URL, CACHE_DIR, VOC_MD5), 'val')

python/setup.py.in

@@ -19,7 +19,8 @@ setup_requires=["requests",
                 "recordio",
                 "matplotlib",
                 "rarfile",
-                "scipy>=0.19.0"]
+                "scipy>=0.19.0",
+                "Pillow"]
 
 if '${CMAKE_SYSTEM_PROCESSOR}' not in ['arm', 'armv7-a', 'aarch64']:
     setup_requires+=["opencv-python"]