กำหนดขนาดรูปภาพแต่รุปภาพไม่ยอมปรับตามขนาดที่กำหนดทำยังไงดีครับ

    <?php
  function ttruncat($text,$numb) {
  if (strlen($text) > $numb) {
    $text = substr($text, 0, $numb);
  //  $text = substr($text,0,strrpos($text," "));
    $etc = " ...";
    $text = $text.$etc;
    }
  return $text;
  }

  ?>
<div id='news'>

</div>
      <!-- Page Content -->
      <div class="container " >
        <!-- Marketing Icons Section -->
        <div class="row">
          <div class="main_featured m-top-100">
            <div class="col-lg-12">
              <div class="head_title text-center">
                <h2>News&Events</h2>
                <div class="separator_auto"></div>
                <br>
              </div>
            </div>
          </div>
          <?php // <?php echo $result["img"]
          while($result=mysqli_fetch_array($query,MYSQLI_ASSOC))
          {
                $txtMessage = $result["txtMessage"];
          ?>
            <div class="col-md-4 thaifont"  style="color:#000000;">
              <div class="portfolio-item">
                <img class="img-responsive" src="login/images/<?php echo $result["img"]?>"    width="750" height="450" >
                <h3   style="color:#000000;"><?php echo $result["title"] ?></h3>
              </div>

              <p >
                <?php echo ttruncat($txtMessage,600)?> </p>
                    <?php
                      if ( $result["a_id"] == "1") {
                    ?>
                <a href="readmore1.php" class="btn btn-info "  style="color:#fff;">ReadMore</a>

                <?php

                    } elseif ($result["a_id"] == "2") {
                      ?>
                  <a href="readmore2.php" class="btn btn-info"  style="color:#fff;">ReadMore</a>

                  <?php

                    }
                    elseif ($result["a_id"] == "3") {
                      ?>
                    <a href="readmore3.php" class="btn btn-info"  style="color:#fff;">ReadMore</a>

                    <?php

                    }
                      ?>
            </div>
            <?php
        }
        ?>

        <?php
        mysqli_close($conn);
        ?>
        </div>
        <!-- /.row -->
      </div>