python 处理pascal voc数据 读取xml文件

Pascal VOC数据的annotation是xml文件，要利用xml文件里的标注信息裁剪出数据~~

from __future__ import division
import os
from PIL import Image
import xml.dom.minidom
import numpy as np

ImgPath = 'C:/Users/liesmars/Desktop/VOC2012/JPEGImages/'
AnnoPath = 'C:/Users/liesmars/Desktop/VOC2012/Annotations/'
ProcessedPath = 'C:/Users/liesmars/Desktop/CropedVOC/'

if not os.path.exists(ProcessedPath):
os.makedirs(ProcessedPath)

imagelist = os.listdir(ImgPath)

for image in imagelist:
print 'a new image:', image
image_pre, ext = os.path.splitext(image)
imgfile = ImgPath + image
xmlfile = AnnoPath + image_pre + '.xml'

DomTree = xml.dom.minidom.parse(xmlfile)
annotation = DomTree.documentElement

filenamelist = annotation.getElementsByTagName('filename') #[<DOM Element: filename at 0x381f788>]
filename = filenamelist[0].childNodes[0].data
objectlist = annotation.getElementsByTagName('object')

i = 1
for objects in objectlist:
# print objects

namelist = objects.getElementsByTagName('name')
# print 'namelist:',namelist
objectname = namelist[0].childNodes[0].data
print objectname

bndbox = objects.getElementsByTagName('bndbox')
cropboxes = []
for box in bndbox:
try:
x1_list = box.getElementsByTagName('xmin')
x1 = int(x1_list[0].childNodes[0].data)
y1_list = box.getElementsByTagName('ymin')
y1 = int(y1_list[0].childNodes[0].data)
x2_list = box.getElementsByTagName('xmax')
x2 = int(x2_list[0].childNodes[0].data)
y2_list = box.getElementsByTagName('ymax')
y2 = int(y2_list[0].childNodes[0].data)
w = x2 - x1
h = y2 - y1

img = Image.open(imgfile)
width,height = img.size

obj = np.array([x1,y1,x2,y2])
shift = np.array([[0.8,0.8,1.2,1.2],[0.9,0.9,1.1,1.1],[1,1,1,1],[0.8,0.8,1,1],[1,1,1.2,1.2],\
[0.8,1,1,1.2],[1,0.8,1.2,1],[(x1+w*1/6)/x1,(y1+h*1/6)/y1,(x2+w*1/6)/x2,(y2+h*1/6)/y2],\
[(x1-w*1/6)/x1,(y1-h*1/6)/y1,(x2-w*1/6)/x2,(y2-h*1/6)/y2]])

XYmatrix = np.tile(obj,(9,1))
cropboxes = XYmatrix * shift

for cropbox in cropboxes:
# print 'cropbox:',cropbox
minX = max(0,cropbox[0])
minY = max(0,cropbox[1])
maxX = min(cropbox[2],width)
maxY = min(cropbox[3],height)

cropbox = (minX,minY,maxX,maxY)
cropedimg = img.crop(cropbox)
cropedimg.save(savepath + '/' + image_pre + '_' + str(i) + '.jpg')
i += 1

except Exception, e:
print e