fagianonzolo

codice:
<?php
$src_im = "img.jpg";

$dst_im = "400.jpg";

$src_im = imagecreatefromjpeg($src_im); // <================ 
list( $src_w , $src_h , $src_type , $src_attr ) = getimagesize( $src_im );

$dst_w = 400;

$dst_h = ceil( $dst_w / ( $src_w / $src_h ) ) ;

imagecopyresampled( $dst_im , $src_im , 0, 0, 0, 0, $dst_w, $dst_h , $src_w, $src_h );
?>