Python Flask server code receiving a XHR send POST request image and save it under the BLOB prefix

Python Flask server code receiving a XHR send POST request image and want to save it. This is the following code as I send the picture thru the web portal:

document.getElementById('file-image').src = URL.createObjectURL(file);

in which will generate the corresponding blob image link as following:

blob:http://127.0.0.1:8080/f4bbec18-31b4-4d5b-b265-409142397ac5

And my header of the request would be like following,

                xhr.open('POST', document.getElementById('file-upload-form').action, true);
                xhr.setRequestHeader('X-File-Name', file.name);
                xhr.setRequestHeader('X-File-Size', file.size);
                xhr.setRequestHeader('file-url', document.getElementById('file-image').src);
                xhr.setRequestHeader("Access-Control-Allow-Origin", "*");
                xhr.setRequestHeader("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
                xhr.setRequestHeader('Content-Type', 'multipart/form-data');
                xhr.send(file);

Now, inside my python flask server, I want to process that "POST" request and save the image into folder:

@app.route('/cv',methods=['POST'])
def getpic():
    print(request.headers.get('file-url'))

Now I want to ask, how can I save the blob linked image and process it.

I am sure that I can see the image as I paste the link to browser as following

Thanks,

Toby.