How to request a picture through authorization?

Question

Node.js

Good afternoon, I can not find an article or methods. Where such a method for obtaining pictures would be described.
The client accesses the server via POST and passes authorization, after which he is given the image for which he made the request.
Let's say this JSON format in the POST request
{
"user":"name",
"password":"222222222",
"ico":"flooded_background"
}

Can someone share the method, of course I would like the client to receive a generated request for an image upon request . Well, or at the request that is described above, he immediately opened the picture. Maybe I don’t imagine the implementation correctly, so I want to hear advice or solutions on this matter.