scrapy爬取图片报错(IOError: cannot identify image file )

Question

最近学习爬虫，使用selenium爬取网站的首页图片，测试获取到了图片的url，但是总是报以下错误，找不到原因，望大侠相助！

代码如下：
item.py

import scrapy

class JiandanItem(scrapy.Item):
    # define the fields for your item here like:
    # name = scrapy.Field()
    image_urls = scrapy.Field()#图片的链接
    images = scrapy.Field()

pipeline.py

import os
import urllib
import scrapy
from scrapy.exceptions import DropItem
from scrapy.pipelines.images import ImagesPipeline
from PIL import Image
from jiandan import settings

class JiandanPipeline(ImagesPipeline)

    def get_media_requests(self, item, info):
        for image_url in item['image_urls']:
            print(image_url)
            yield scrapy.Request(image_url)


    def item_completed(self, results, item, info):
        image_paths = [x['path'] for ok, x in results if ok]
        if not image_paths:
            raise DropItem("Item contains no images")
        return item

middlewares.py

import scrapy
from selenium import webdriver
from scrapy.http import HtmlResponse
import time

class PageMiddleware(object):
    def process_request(self, request, spider):
        if request.meta.has_key('PhantomJS'):
            return
        else:
            driver = webdriver.PhantomJS()
            driver.get(request.url)
            time.sleep(1)
            content = driver.page_source.encode("utf-8")
            # print(content)
            driver.quit()

            return HtmlResponse(request.url, encoding="utf-8",body=content, request=request)

jiandanSpider.py

import scrapy
from jiandan.items import JiandanItem

from scrapy.crawler import CrawlerProcess

class jiandanSpider(scrapy.Spider):
    name = 'jiandan'
    allowed_domains = ['http://www.172mn.com/']
    start_urls = ["http://www.172mn.com/"]

    def parse(self, response):
        item = JiandanItem()
        item['image_urls'] = response.xpath("//li//img/@src").extract()
        yield item

settings.py

BOT_NAME = 'jiandan'
SPIDER_MODULES = ['jiandan.spiders']
NEWSPIDER_MODULE = 'jiandan.spiders'
HTTPERROR_ALLOWED_CODES = [403]
ROBOTSTXT_OBEY = False
DEFAULT_REQUEST_HEADERS = {
    'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.10 Safari/537.36',
    'Accept' : 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8',
    'Accept-Language' : 'zh-CN,zh;q=0.9',
}
DOWNLOADER_MIDDLEWARES = {
   'jiandan.middlewares.PageMiddleware': 543,
}
ITEM_PIPELINES = {
    'jiandan.pipelines.JiandanPipeline': 1,
}
IMAGES_STORE = '/home/python/Desktop/'
DOWNLOAD_DELAY = 3
IMAGES_THUMBS = {
    'small': (50, 50),
    'big': (200, 200),
}

错误信息：

http://pic.iscoy.net/uploads/180309/1-1P30Z2345c00.jpg
2018-05-21 22:33:58 [selenium.webdriver.remote.remote_connection] DEBUG: POST http://127.0.0.1:34265/wd/hub/session {"desiredCapabilities": {"platform": "ANY", "browserName": "phantomjs", "version": "", "javascriptEnabled": true}}
2018-05-21 22:33:58 [selenium.webdriver.remote.remote_connection] DEBUG: Finished Request
2018-05-21 22:33:58 [selenium.webdriver.remote.remote_connection] DEBUG: POST http://127.0.0.1:34265/wd/hub/session/ff87b910-5d03-11e8-8234-c5368f3096da/url {"url": "http://pic.iscoy.net/uploads/180309/1-1P30Z2345c00.jpg", "sessionId": "ff87b910-5d03-11e8-8234-c5368f3096da"}
2018-05-21 22:34:00 [selenium.webdriver.remote.remote_connection] DEBUG: Finished Request
2018-05-21 22:34:01 [selenium.webdriver.remote.remote_connection] DEBUG: GET http://127.0.0.1:34265/wd/hub/session/ff87b910-5d03-11e8-8234-c5368f3096da/source {"sessionId": "ff87b910-5d03-11e8-8234-c5368f3096da"}
2018-05-21 22:34:01 [selenium.webdriver.remote.remote_connection] DEBUG: Finished Request
2018-05-21 22:34:01 [selenium.webdriver.remote.remote_connection] DEBUG: DELETE http://127.0.0.1:34265/wd/hub/session/ff87b910-5d03-11e8-8234-c5368f3096da {"sessionId": "ff87b910-5d03-11e8-8234-c5368f3096da"}
2018-05-21 22:34:01 [selenium.webdriver.remote.remote_connection] DEBUG: Finished Request
2018-05-21 22:34:01 [scrapy] DEBUG: Crawled (200) <GET http://pic.iscoy.net/uploads/180309/1-1P30Z2345c00.jpg> (referer: None)
2018-05-21 22:34:01 [scrapy] DEBUG: File (downloaded): Downloaded file from <GET http://pic.iscoy.net/uploads/180309/1-1P30Z2345c00.jpg> referred in <None>
2018-05-21 22:34:01 [scrapy] ERROR: File (unknown-error): Error processing file from <GET http://pic.iscoy.net/uploads/180309/1-1P30Z2345c00.jpg> referred in <None>
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/scrapy/pipelines/files.py", line 355, in media_downloaded
    checksum = self.file_downloaded(response, request, info)
  File "/usr/local/lib/python2.7/dist-packages/scrapy/pipelines/images.py", line 95, in file_downloaded
    return self.image_downloaded(response, request, info)
  File "/usr/local/lib/python2.7/dist-packages/scrapy/pipelines/images.py", line 99, in image_downloaded
    for path, image, buf in self.get_images(response, request, info):
  File "/usr/local/lib/python2.7/dist-packages/scrapy/pipelines/images.py", line 112, in get_images
    orig_image = Image.open(BytesIO(response.body))
  File "/usr/local/lib/python2.7/dist-packages/PIL/Image.py", line 2590, in open
    % (filename if filename else fp))
IOError: cannot identify image file <cStringIO.StringI object at 0x7f7c38d2fcf0>