{
  "pimage": [
    {
      "limage": "http://images.bestbuy.com/BestBuy_US/images/products/7306/7306011_sb.jpg",
      "timage": "http://images.bestbuy.com/BestBuy_US/images/products/7306/7306011_s.gif",
      "mimage": "http://images.bestbuy.com/BestBuy_US/images/products/7306/7306011fp.gif",
      "lfimage": "http://img.bbystatic.com/BestBuy_US/images/products/7306/7306011_sa.jpg"
    }
  ]
}

{
  "pimage": [
    {
      "limage": "http://images.bestbuy.com/BestBuy_US/images/products/7306/7306011_sb.jpg"
    },
    {
      "limage": "http://images.bestbuy.com/BestBuy_US/images/products/7306/7306011_s.gif"
    },
    {
      "limage": "http://images.bestbuy.com/BestBuy_US/images/products/7306/7306011_s.gif"
    },
    {
      "limage": "http://images.bestbuy.com/BestBuy_US/images/products/7306/7306011_s.gif"
    }
  ]
}

var myObj = {
  "pimage": [
    {
      "limage": "http://images.bestbuy.com/BestBuy_US/images/products/7306/7306011_sb.jpg",
      "timage": "http://images.bestbuy.com/BestBuy_US/images/products/7306/7306011_s.gif",
      "mimage": "http://images.bestbuy.com/BestBuy_US/images/products/7306/7306011fp.gif",
      "lfimage": "http://img.bbystatic.com/BestBuy_US/images/products/7306/7306011_sa.jpg"
    }
  ]
}
var myFunc = function(obj) {
  var keys = Object.keys(obj.pimage[0]);
  var newObj = {"pimage":[]};
  keys.forEach(function(k) {
    var newImg = {};
    newImg['limage'] = k;
    newObj.pimage.push(newImg);
  });
return newObj;
}

console.log(myFunc(myObj));