uploading image in codeigniter via ajax

Question

Currently I am uploading image in codeigniter via ajax. In this all my input fields are taken, but input file was not getting. I am getting error undefine "image name" how to do image upload via ajax. I have attached my code below,

HTML:

<form method="post"  enctype="multipart/form-data" action="" id="newsFeedForm">
<input type="file" name="newsimages<?php echo $i; ?>[]" id="newsimages<?php echo $i; ?>" data-feed="feed<?php echo $i; ?>" multiple>
<input type="button" id="newsSubmit" value="Update" class="btn btn-primary btn-sm pull-right mt10 col-lg-2 col-sm-2 col-xs-2 mt10" name="newsSubmit" onclick="updateFeedDatabase(<?php echo $i.','.$fed->news_id; ?>);">
</form>

ajax:
function updateFeedDatabase(id, nid){
   var myData = $('#your_form').serialize(); 
    //alert(formData);

    $.ajax({
        type:"POST",
        contentType:attr( "enctype", "multipart/form-data" ),
        url:"<?=base_url();?>nhome/updateFeed/"+id+"/"+nid,
        data: myData,
        cache: false,
        processData: false,
        success: function (data) {
           alert(data);
        },
        error: function(data){
        //error function
    }

    });
}

Model:

public function updatefeedDb($id,$nid){
    $message = $this->input->post('newsMessage'.$id);
    $status = $this->input->post('newsstatus'.$id);
    echo $_FILES['newsimages'.$id]['name'];

    if (empty($_FILES['newsimages'.$id]['name'])) {
        echo "I am not empty";
    }else{
        echo "I am empty";
    }   

}

In this above code, I am getting undefined "newsimages1". How to get image in to ajax page, Can you please help in this task.