Image cannot resize using PHP

I'm trying to resize an image that I copy from Flickr. But it seems I'm getting the original size itself. Here is my code:

$img = Input::get('FlickrUrl');
$filename = gmdate('Ymdhis', time());
copy($img, $_SERVER["DOCUMENT_ROOT"].'/upload/'.$filename.'.jpeg');
$newImg = '/upload/'.$filename.'.jpeg';
list($CurWidth, $CurHeight) = getimagesize($_SERVER["DOCUMENT_ROOT"].$newImg);

$width = $CurWidth;
$height = $CurHeight;
$image_ratio = $CurWidth / $CurHeight;

//resize image according to container
$container_width = 300;
$container_height = 475;

if($CurWidth > $container_width)
{
    $CurWidth = $container_width;
    $CurHeight = $CurWidth / $image_ratio;
}
if($CurHeight > $container_height)
{
    $CurHeight = $container_height;
    $CurWidth = $CurHeight * $image_ratio;
}

if($CurWidth < $container_width)
{
    $CurWidth = $container_width;
    $CurHeight = $CurWidth / $image_ratio;
}
if($CurHeight < $container_height){
    $CurHeight = $container_height;
    $CurWidth = $CurHeight * $image_ratio;
}

$img_orginal = $_SERVER["DOCUMENT_ROOT"].'/upload/'.$filename.'.jpeg';
$img_org = ImageCreateFromJPEG($img_orginal);
$NewCanves  = imagecreatetruecolor($CurWidth, $CurHeight);
imagecopyresized($NewCanves, $img_org, 0, 0, 0, 0, $CurWidth, $CurHeight, $width, $height);
$finalImg = '/upload/'.$filename.'.jpeg';


return Response::json(["success"=>"true", "images"=>$finalImg, "width"=>$CurWidth, "height"=>$CurHeight]);

First I copy the Image from the URL, saves it in my server and then trying to resize it. Can't understand whats wrong with this code.

The problem here is you don't save your file. After:

imagecopyresized($NewCanves, $img_org, 0, 0, 0, 0, $CurWidth, $CurHeight, $width, $height);
$finalImg = '/upload/'.$filename.'.jpeg'

you should add:

imagejpeg($NewCanves, $finalImg);

to save it in filesystem