Card has an image:

[
  {
    "cardId": "CS2_188",
    "dbfId": 242,
    "name": "Abusive Sergeant",
    "cardSet": "Classic",
    "type": "Minion",
    "faction": "Alliance",
    "rarity": "Common",
    "cost": 1,
    "attack": 1,
    "health": 1,
    "text": "<b>Battlecry:</b> Give a minion +2_Attack this turn.",
    "flavor": "ADD ME TO YOUR DECK, MAGGOT!",
    "artist": "Luca Zontini",
    "collectible": true,
    "playerClass": "Neutral",
    "img": "https://d15f34w2p8l1cc.cloudfront.net/hearthstone/8cc6f521dac86c945f12424cf0a4c4b78d73157d4797e3169c3cc8dbe2fbb9d1.png",
    "imgGold": "https://d15f34w2p8l1cc.cloudfront.net/hearthstone/2866f600b26992ef766b00d90a97c372f99cd7bb9c04d7a0391c798ddfeb75fd.png",
    "locale": "enUS",
    "mechanics": [
      {
        "name": "Battlecry"
      }
    ]
  }
]

Card has <b>no</b> image:

[
  {
    "cardId": "HERO_11",
    "dbfId": 78065,
    "name": "The Lich King",
    "cardSet": "Hero Skins",
    "type": "Hero",
    "rarity": "Free",
    "health": 30,
    "artist": "Alex Horley Orlandelli",
    "collectible": true,
    "playerClass": "Death Knight",
    "locale": "enUS"
  }
]