Your can use Django REST framework and python Requests library to Programmatically saving image to Django ImageField
Here is a Example:
import requests
def upload_image():
# PATH TO DJANGO REST API
url = "http://127.0.0.1:8080/api/gallery/"
# MODEL FIELDS DATA
data = {'first_name': "Rajiv", 'last_name': "Sharma"}
# UPLOAD FILES THROUGH REST API
photo = open('/path/to/photo'), 'rb')
resume = open('/path/to/resume'), 'rb')
files = {'photo': photo, 'resume': resume}
request = requests.post(url, data=data, files=files)
print(request.status_code, request.reason)