Tensorflow 读取XML文件内容并对图片等比例缩放

Posted 2021-08-21 ʚVVcatɞ

根据XML文件中对图片标记的信息读取，并显示在图片中。

xml 文件内容：

<annotation>
	<folder>OXIIIT</folder>
	<filename>samoyed_100.jpg</filename>
	<source>
		<database>OXFORD-IIIT Pet Dataset</database>
		<annotation>OXIIIT</annotation>
		<image>flickr</image>
	</source>
	<size>
		<width>500</width>
		<height>334</height>
		<depth>3</depth>
	</size>
	<segmented>0</segmented>
	<object>
		<name>dog</name>
		<pose>Frontal</pose>
		<truncated>0</truncated>
		<occluded>0</occluded>
		<bndbox>
			<xmin>136</xmin>
			<ymin>1</ymin>
			<xmax>344</xmax>
			<ymax>304</ymax>
		</bndbox>
		<difficult>0</difficult>
	</object>
</annotation>

目标原图片：

实现代码：

import tensorflow as tf
import matplotlib.pyplot as plt
from lxml import etree
from matplotlib.patches import Rectangle  

img = tf.io.read_file(r'./images/samoyed_100.jpg')  #  读取图片
img = tf.image.decode_jpeg(img)  # 对图像进行解码
plt.imshow(img)
plt.show()

xml = open(r'./xmls/samoyed_100.xml').read()  # 读取 xml文件
sel = etree.html(xml)  # 对 xml 文件进行解析
width = sel.xpath('//size/width/text()')[0]
height = sel.xpath('//size/height/text()')[0]
xmin = sel.xpath('//bndbox/xmin/text()')[0]
ymin = sel.xpath('//bndbox/ymin/text()')[0]
xmax = sel.xpath('//bndbox/xmax/text()')[0]
ymax = sel.xpath('//bndbox/ymax/text()')[0]
width = int(width)
height = int(height)
xmin = int(xmin)
ymin = int(ymin)
xmax = int(xmax)
ymax = int(ymax)
plt.imshow(img.numpy())
rect = Rectangle((xmin, ymin), (xmax - xmin), (ymax - ymin), fill=False, color='red')  # fill=False 不需要填充
ax = plt.gca()  # 获取当前图像
ax.axes.add_patch(rect)  # 添加矩形框
plt.show()

得到

对图片进行比例缩放：

img = tf.image.resize(img, [224, 224])
img = img / 255   # 标准化
xmin = (xmin / width) * 224
ymin = (ymin / height) * 224
xmax = (xmax / width) * 224
ymax = (ymax / height) * 224

plt.imshow(img.numpy())
rect = Rectangle((xmin, ymin), (xmax - xmin), (ymax - ymin), fill=False, color='red')
ax = plt.gca()
ax.axes.add_patch(rect)
plt.show()

缩放后：