如何从PHP中获取MySQLi获取数组中的单个值？

I want to fetch a single value of $row_img['image_name'] from an array $row_img. $images[] stores all the values. I want to print $images[1].

//The Code

while($row_img = mysqli_fetch_array($result_img)){ 
$images[] = $row_img['image_name']; 

} 
 print($images[1]);

Here are the array values:

$images[0] => 1431731493bg-2 - Copy.jpg
$images[1] => testing.jpg
$images[2] => housing.jpg

The error which is shown:

Notice: Undefined variable: images in C:\wamp\wwwightenter\property.php on line 96
Call Stack
#   Time    Memory  Function    Location
1   0.0020  304616  {main}( )   ..\property.php:0