Display uploaded images on button click

On click of button preview i need the uploaded images to be shown ,the scripts it's working fine for changing event but not for the click one.

HTML

 <form action="test.php" enctype="multipart/form-data" id="mainform" method="post" name="mainform">
Imagine 1:<br>
 <input type="file" name="img1" id="img1"><br>
     <br><br>     
Imagine 2 :<br>
 <input type="file" name="img2" id="img2"><br>
     <br>
 Imagine 3 :<br>
 <input type="file" name="img3" id="img3"><br> 
     <br>
 Imagine 4 :<br>
 <input type="file" name="img4" id="img4"><br>    
     <br>
 Imagine 5 :<br>
 <input type="file" name="img5" id="img5"><br>   
     <br>
 Imagine 6 :<br>
 <input type="file" name="img6" id="img6"><br>   
     <br>
 Imagine 7 :<br>
 <input type="file" name="img7" id="img7"><br>    
     <br>
 Imagine 8 :<br>
 <input type="file" name="img8" id="img8"><br>    
     <br>
 Imagine 9 :<br>
 <input type="file" name="img9" id="img9"><br>   
     <br>
 Imagine 10 :<br>
 <input type="file" name="img10" id="img10"><br>    
     <br>
 Imagine 11 :<br>
 <input type="file" name="img11" id="img11"><br> 
     <br>
 Imagine 12 :<br>
 <input type="file" name="img12" id="img12"><br>    
     <br>
 Imagine 13 :<br>
 <input type="file" name="img13" id="img13"><br>    
     <br>
 Imagine 14 :<br>
 <input type="file" name="img14" id="img14"><br>     
     <br>
 Imagine 15 :<br>
 <input type="file" name="img15" id="img15"><br>    
     <br />
     Preview:
     <br />
     <input type="checkbox" id="previz" />Preview
</form>
<div id="#previzdiv">
<img src="" id="preview-img1">
<img src="" id="preview-img2">
<img src="" id="preview-img3">
<img src="" id="preview-img9">
<img src="" id="preview-img5">
</div>

Jquery:

$("#center2 #forme #previz").change(function(){
if(this.checked){
for(i=1;i<15;i++){
j = $("form#mainform #img"+i);
console.log(j);
readURL(j);
}
}

});
function readURL(input) {
        if (input.files && input.files[0]) {
            var reader = new FileReader();

            reader.onload = function (e) {
                imgId = '#preview-'+$(input).attr('id');
                $(imgId).attr('src', e.target.result);
            }

            reader.readAsDataURL(input.files[0]);
        }
      }


      $("form#mainform input[type='file']").change(function(){
        readURL(this);
        console.log(this);
      });

The console log from "j" should look like <input type="file" name="img1" id="img1"> yet it different from what change event is console logging.Is the approach correct? JSFIDDLE:http://ift.tt/1JrktCS