How to upload image to start node using API?

Building Flows
1

Referencing the docs at:

I want to send an image from a client to the Workflow.

I see the snippet but it is for a STRING to be sent as data but not sure how to send using an image png as a binary object.

import requests
import json

url = "https://app.scade.pro/api/v1/scade/flow/75929/execute"

payload = json.dumps({
  "start_node_id": "start",
  "end_node_id": "end",
  "result_node_id": "end",
  "node_settings": {
    "start": {
      "data": {
        "img": {STRING}
      }
    }
  }
})
headers = {
  'Authorization': 'Basic {ACCESS_TOKEN}',
  'Content-Type': 'application/json'
}

response = requests.request("POST", url, headers=headers, data=payload)

print(response.text)

I’m using Python Requests so I have tried to send using files but that doesn’t seem to be read by the server.

UPDATE: What does work is referencing a URL of the image then getting an imgflip URL as a return such as:

 "result": {
        "data": null,
        "img2": "https://i.imgflip.com/4zcvfa.jpg",
        "inputs": null,
        "success": {
            "data": null,
            "img2": "https://i.imgflip.com/4zcvfa.jpg",
            "inputs": null
        }
    },

img2 is my return variable.