I'm using http public cache all over an images website to allow clients and anyone between the clients and my server (eg: cloudflare, isp, etc) to cache HTML, assets (js/css/icons), and images (the main content of the website). But I don't want nginx to cache these images, because it will take too much space. I'm not sure whether it's happening, I don't know how to check.
So how do I check, and if it's happening, how do I stop it, without also stopping client and proxies cache?
Note: I'm using nginx as web server with fastcgi, and not as a proxy