POST with image

[famousuniverse]

How do you send a POST with an image and some text. Sending a POST is straight forward:

POST {{host}}/nameOfEndpoint
Content-Type: application/json
{
"id": 3,
"key": "blue",
"image": ""
}

But How do I test an image, can someone please point to a tutorial of a definitively working version. Thank you!