您可以尝试：

(?i)https?[^<>\s\'\"=]+(?:jpg|png|webp)\b|[^:<>\s\'\"=]+(?:jpg|png|webp)\b

Regex demo.

import re

s = '''img src=https://www.test.com/abc.jpg background:../example/test.png <div> images/test.webp image.pnghellobackground-image: url('../images/pics/mobile/img.JPG')'''
pat = re.compile(r'(?i)https?[^<>\s\'\"=]+(?:jpg|png|webp)\b|[^:<>\s\'\"=]+(?:jpg|png|webp)\b')

for m in pat.findall(s):
    print(m)

图纸：

https://www.test.com/abc.jpg
../example/test.png
images/test.webp
../images/pics/mobile/img.JPG

你觉得怎么样：

re.findall(r'(?=:[^\S])?(?:https?://)?[\./]*[\w/\.]+\.(?:jpg|png|gif|jpeg|webp)', inputString)

其中：

"img src=http://another.org/hola.gif https://www.test.com/abc.jpg background:../example/test.png <div> images/test.webp image.pnghello"

给出：

['http://another.org/hola.gif',
 'https://www.test.com/abc.jpg',
 '../example/test.png',
 'images/test.webp',
 'image.png']

这可能需要更多的测试样本：）