simg service json spec

service.json

{
  "uri": "demo/345ad0f7.jpg",
  "size": [3200, 2400],
  "delegates": [{
    "uri": "demo/image-xsmall.jpg",
    "size": [320, 240]
  }, {
    "uri": "demo/image-small.jpg",
    "size": [640, 480]
  }, {
    "uri": "demo/image-large.jpg",
    "size": [1600, 1080]
  }]
}