header("Content-type: image/jpeg"); 
$file = "111.jpg"; 
$percent = 1.5; //圖片壓縮比 
list($width, $height) = getimagesize($file); //獲取原圖尺寸 
//縮放尺寸 
$newwidth = $width * $percent; 
$newheight = $height * $percent; 
$src_im = imagecreatefromjpeg($file); 
$dst_im = imagecreatetruecolor($newwidth, $newheight); 
imagecopyresized($dst_im, $src_im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height); 
imagejpeg($dst_im); //輸出壓縮后的圖片 
imagedestroy($dst_im); 
imagedestroy($src_im);