Best way to store image on web api

I have an android project which is link to a dedicated web api on flask and which is deployed on a raspberry pi. They are no front web page for this web application. Link to this api i have a database. The Api receive json request from android app, ask to the database, and send response also in json.

my problematic is, i have to upload images on the server from android on and send it back when android send a resquest for have access to them. my question is: How can i store images efficiently?

Until now, i save it on a ftp server and when the android app send a request, i download it on the web serveur from the ftp and send a link to download it. Of course a ftp server is not really the best way for do this job.

what is the good way to store images? should i store them directly in the db?

thank you in advance