function thumbnail($file, $save_filename, $max_width, $max_height){
 $src_img = ImageCreateFromJPEG($file); //JPG파일로부터 이미지를 읽어옵니다
 $img_info = getImageSize($file);//원본이미지의 정보를 얻어옵니다
 $img_width = $img_info[0];
 $img_height = $img_info[1];
 if(($img_width/$max_width) == ($img_height/$max_height)){
  $dst_width=$max_width;
  $dst_height=$max_height;
 }elseif(($img_width/$max_width) < ($img_height/$max_height)){
  $dst_width=$max_height*($img_width/$img_height);
  $dst_height=$max_height;
 }else{
  $dst_width=$max_width;
  $dst_height=$max_width*($img_height/$img_width);
 }
 $dst_img = imagecreatetruecolor($dst_width, $dst_height); //타겟이미지를 생성합니다
 ImageCopyResized($dst_img, $src_img, 0, 0, 0, 0, $dst_width, $dst_height, $img_width, $img_height);
 ImageInterlace($dst_img);
 ImageJPEG($dst_img,  $save_filename); //실제로 이미지파일을 생성합니다
 ImageDestroy($dst_img);
 ImageDestroy($src_img);
}

//사용 예문
if($_FILES['Filedata']['name']){
  $uploadDir1="../b_img/temp/"; //원본
  $uploadDir2="../b_img/$reg_date/"; //썸네일
  $uploadFile1="$uploadDir1".iconv("utf-8","euc-kr",$_FILES['Filedata']['name']); //원본경로
  $uploadFile2="$uploadDir2".iconv("utf-8","euc-kr",$_FILES['Filedata']['name']);  //썸네일경로
  //$uploadFile = "$uploadDir". basename($_FILES['Filedata']['name']);
  move_uploaded_file($_FILES['Filedata']['tmp_name'],$uploadFile1);
  chmod($uploadFile1,0707);
  chmod($uploadFile2,0707); 
  thumbnail($uploadFile1,$uploadFile2,"180","135");  
 }