{
  "$schema": "https://developer.microsoft.com/json-schemas/sp/v2/column-formatting.schema.json",
  "elmType": "img",
  "attributes": {
    "src": "@thumbnail.medium"
  },
  "style": {
    "display": "block",
    "margin": "0 auto",
    "max-height": "42px"
  }
}