Python PIL 保存的黑色图像

Question

i'm trying to get screenshot of phone element in site. I save the screenshot of entire page, get element coordinates and crop screenshot in phone element place. But after cropping i got black image. I don't understand why, and how i can fixe it.

My code:

# coding: utf-8
from selenium import webdriver
from selenium.webdriver.common.keys import Keys
from selenium.webdriver.chrome.options import Options
from selenium.webdriver.common.action_chains import ActionChains
from selenium.webdriver.common.proxy import *
import time
from PIL import Image

driver = webdriver.Chrome(executable_path='chromedriver')
driver.get('https://www.avito.ru/moskva/audio_i_video/televizor_samsung_i_tumba_iz_stekla_k_nemu_838296913')
button = driver.find_element_by_xpath('//*[@id="i_contact"]/div[3]/div/span[1]/span')
button.click()
time.sleep(4)
element = driver.find_element_by_xpath('//*[@id="i_contact"]/div[3]/div/span[1]')
location = element.location
size = element.size
driver.save_screenshot('screenshot.png')
driver.quit()

im = Image.open('screenshot.png')

left = location['x']
top = location['y']
right = location['x'] + size['width']
bottom = location['y'] + size['height']


im = im.crop((left, top, right, bottom))
im.save('screenshot.png')

Screenshot after Selenium save:

Screenshot after cropping:

Answer 1

I would check the value of 'location'. If your crop co-ordinates were outside of the image, then you would see black. So for example -

im = im.crop((-300, -300, -200, -200))

would give a black image.

Answer 2

The reason may be the image was saved as a normalized version, which means the value of each pixel is in [0,1]. Try multiply each pixel by 255 and view again.