mime type

hello is this code OK??? "fotos" is an array of uploaded files (images).. i want to process them in case they are images...if not, don't process.. is myme type case sensitive?? some of our customers, have problems uploading images... thanks in advance..

     $tipo = $HTTP_POST_FILES["fotos"]["type"][$a];
     $tipo = ( strstr($tipo, '; name') ) ? str_replace(strstr($tipo, '; name'), '', $tipo) : $tipo;   //some opera patch¿¿¿

     if (
              ($tipo == "image/png") ||
              ($tipo == "image/jpeg") ||
              ($tipo == "image/jpg") ||
              ($tipo == "image/bmp") ||
              ($tipo == "image/gif")ç
       )
      {
           //process.
       }

else

       {
           //do nothing
       }