Hi, I would like to send a photo taken from an app I developed with AppInventor to a Linux (Ubuntu) server I have, and use the photo to run a python script I have on the Linux server to send the photo back to the app, is this possible? I would like to try connecting to the Linux server first, but I am having trouble finding a way to do this. 
Are you able to send an image file to your server via curl or postman or using a form in a browser?
Install (if you don't have it) an FTP Server on your Linux.