/* 一覧表示の画像のリサイズ */
function image_resize( img , width_size , height_size ) {
  var now_width  = img.width;
  var now_height = img.height;

  var rate =  (width_size / height_size)  * height_size * (now_height / now_width );

  if(height_size < rate ){
    img.height = height_size;
    img.style.position = "relative";

/*    var tmp_width = now_width * height_size / now_height ;
    var move_px = ( width_size - tmp_width ) /2;

    img.style.left = move_px + "px";
*/
  }else{
    img.width = width_size;
    img.style.position = "relative";

    var tmp_height = now_height * width_size / now_width ;
    var move_px = ( height_size - tmp_height ) /2;

    img.style.top = move_px + "px";

  }
}