I'm trying to receive images on my python program, I've searched a lot on the internet but most of them are just tutorials about sending images. I found a few about receiving but none of them worked for me. All the other ones with receiving did it using a GET request first, which is not what I want. I'm sending a cURL POST request with a file in it (later on it will be sent from a real server, not a cURL) I want the server to keep listening until I upload/POST an image, then I want to receive the image and display it using PIL.

Here is the code I found online but doesn't work, I really have no clue how to receive images.

import socket
import struct
from PIL import Image

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind(('127.0.0.1', 12801))
s.listen(1000)

print('Waiting for data...')

client, addr = s.accept()
print('got connected from', addr)

buf = b''            # this caused an error, I added a b so it would be read as bytes and not string
while len(buf)<4:
    buf += client.recv(4-len(buf))
size = struct.unpack('!i', buf)
print("receiving %s bytes" % size)

with open('tst.jpg', 'wb') as img:
    while True:
        data = client.recv(1024)
        if not data:
            break
        img.write(data)
print('received image')

Here is the output when I send a 101.345 bytes JPG file

Waiting for data...
got connected from ('127.0.0.1', 51861)
receiving 1347375956 bytes

1347375956 bytes... that's clearly bugged and not working properly. It's also stuck at that part just waiting.

Just to show you how I got the sending part working and how easy that was (it's not sending to a python program/server, but to an ESP webserver)..:

url = ' http://192.168.x.xx/fupload'
files = {'media': open('converted_image.bmp', 'rb')}
req.post(url, files=files)

I hope anyone can help me out.

Hi Flaskers,

I'm having difficulty receiving image on the Flask backend:

@auth_blueprint.route('/auth/check_image', methods=['POST'])
@cross_origin()
def check_image():
    try:
        image_given = request.files['photo']  # <-- image won't make it to Flask
        img = Image.open(image_given.stream)
        return jsonify({'status': 'OK', 'message': f'{img.width} {img.height}'})

Kivy front-end:

img = {'file': ('photo': open(f'{self.image_path}/example.jpg', 'rb'))}
try:
    response = requests.post('http://www.example.com/auth/check_image', files=img)
    print(str(response.content, 'utf-8'))

Error output:

<title>500 Internal Server Error</title>
03-02 17:06:26.295 15175 15678 I python  : <h1>Internal Server Error</h1>
03-02 17:06:26.295 15175 15678 I python  : <p>The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application.</p>

Error output from the backend:

"content":"400 Bad Request: The browser (or proxy) sent a request that this server could not understand.","status":"fail"

I've found this block of code that allegedly works:

from flask import Flask, request, jsonify

app = Flask(__name__)

@app.route("/im_size", methods=["POST"])
def process_image():
    file = request.files['image']
    # Read the image via file.stream
    img = Image.open(file.stream)

    return jsonify({'msg': 'success', 'size': [img.width, img.height]})


if __name__ == "__main__":
    app.run(debug=True)

url = 'http://127.0.0.1:5000/im_size'
my_img = {'image': open('test.jpg', 'rb')}
r = requests.post(url, files=my_img)

# convert server response into JSON format.
print(r.json())

I found the code here https://jdhao.github.io/2020/04/12/build_webapi_with_flask_s2/, strangely I'm getting status code 400 using it.

Thank you for any insight.