What is the best way to transfer binary content (In my case image) to the client from server in java ee?

I want to do similar to many sites, which upon interaction from user, displays image, which is downloaded from Server.

1. Is it possible from REST API? I got answer that it can be used by using multipart-form type.But doesn't this become POST, and by POST, isn't it be used to add something in SERVER?

2. I also got suggestion by encoding to base64, which likely increases size by 33%.Should I opt this?

3. Using SOAP, which I have no idea about.

4. Websockets?

5. Or should i just link it to source of image, but secure the folder of image in a secure way? but how?