OpenCV open image with URL

Question

I keep getting an error when running the code below

import cv2
import urllib3 as urllib
import requests
import numpy as np

url = "https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2Fwallup.net%2Fwp-content%2Fuploads%2F2016%2F03%2F10%2F343179-landscape-nature.jpg"

r = requests.get(url)

imgar = np.array(bytearray(r.text,'utf-8'),dtype=np.uint8)
img = cv2.imdecode(imgar,-1)
cv2.imshow('img',img)
cv2.waitKey()

Error:

cv2.imshow('img',img)
cv2.error: OpenCV(4.5.1) C:\Users\appveyor\AppData\Local\Temp\1\pip-req-build-kh7iq4w7\opencv\modules\highgui\src\window.cpp:376: error: (-215:Assertion failed) size.width>0 && size.height>0 in function 'cv::imshow'

This error keeps happening no matter what I change the photo to and I'm unsure why, thanks

cv2.VideoCapture should work. Or download the file to a temp folder and open with imread — Micka
– Micka, Commented Jan 15, 2021 at 21:08

Ori David · Accepted Answer · 2024-03-08 12:56:27Z

3

urllib.request.urlopen() is the proper way to download media when working with opencv-python.

import cv2
import urllib.request
import numpy as np
url = "https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2Fwallup.net%2Fwp-content%2Fuploads%2F2016%2F03%2F10%2F343179-landscape-nature.jpg"
url_response = urllib.request.urlopen(url)
img = cv2.imdecode(np.array(bytearray(url_response.read()), dtype=np.uint8), -1)

edited Mar 8, 2024 at 12:56

answered Jan 15, 2021 at 20:40

Ori David

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1 Comment

Rafael Goulart Over a year ago

This is the only method that worked for me and properly preserved the original image colors.

benan.akca · Accepted Answer · 2021-01-15 21:07:04Z

2

You can try this:

import urllib.request
url_response = urllib.request.urlopen(url)
img_array = np.array(bytearray(url_response.read()), dtype=np.uint8)
img = cv2.imdecode(img_array, -1)
cv2.imshow('URL Image', img)
cv2.waitKey()

An alternative way:

import cv2
import urllib3 as urllib
import requests
import numpy as np
import io
import PIL
url = "https://s3-us-west-2.amazonaws.com/uw-s3-cdn/wp-content/uploads/sites/6/2017/11/04133712/waterfall-750x500.jpg"
r = requests.get(url)

response = requests.get(url)
image_bytes = io.BytesIO(response.content)
img = PIL.Image.open(image_bytes)
img.show()

answered Jan 15, 2021 at 21:07

benan.akca

1114 bronze badges

1 Comment

Seitzy Over a year ago

I got the second method to work, thanks :)

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