Create a image on your account with the specified parameters. Don't forget to specify POST as the request method as GET will call the list action rather than create.
https://streamio.com/api/v1/images.format
POST
201
Simplest case scenario is to just post with the file parameter set to a image file on your hard drive.
curl -u username:password \ -F file=@path/to/image.jpg \ https://streamio.com/api/v1/images.json