se hai le librerie gd installate lo puoi fare facilmente, questo è un'esampio di codice che serve a rimpicciolire le immagini mantenendo le prorporzioni:
Codice PHP:
<?
$destinazione_img_rimpicciolita = "...";
$maxx = 80;
$maxy = 80;
$source_image_URL = "...";
list($width, $height, $type) = getimagesize($source_image_URL);
switch($type){
case 1:
$source_image = imagecreatefromgif($source_image_URL);
break;
case 2:
$source_image = imagecreatefromjpeg($source_image_URL);
break;
case 3:
$source_image = imagecreatefrompng($source_image_URL);
break;
}
$percent1 = $width / $maxx;
$percent2 = $height / $maxy;
$percent = max($percent1,$percent2);
$new_eight = round($height /$percent);
$new_width = round($width /$percent);
$dest_image = ImageCreateTrueColor($new_width, $new_eight);
imagecopyresampled ($dest_image, $source_image, 0, 0, 0, 0, $new_width, $new_eight, $width, $height);
header("Content-type: image/jpeg");
imagejpeg($dest_image, $destinazione_img_rimpicciolita);
imagedestroy($dest_image);
imagedestroy($source_image);
?>