Hi rechie16,
You can change just width and height of the div where you are placing the image tag like below.
$("#dvPreview img").attr('width', '250px'); // change width.
$("#dvPreview img").attr('height', '250px'); // change height.
Refer Below Sample Code.
HTML
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
</head>
<body>
<form id="form1" runat="server">
<input id="fileupload" type="file" />
<hr />
<b>Live Preview</b>
<br />
<br />
<div id="dvPreview">
</div>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<script language="javascript" type="text/javascript">
$(function () {
$("#fileupload").change(function () {
$("#dvPreview").html("");
var regex = /^([a-zA-Z0-9\s_\\.\-:])+(.jpg|.jpeg|.gif|.png|.bmp)$/;
if (regex.test($(this).val().toLowerCase())) {
if ($.browser.msie && parseFloat(jQuery.browser.version) <= 9.0) {
$("#dvPreview").show();
$("#dvPreview")[0].filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = $(this).val();
}
else {
if (typeof (FileReader) != "undefined") {
$("#dvPreview").show();
$("#dvPreview").append("<img />");
var reader = new FileReader();
reader.onload = function (e) {
$("#dvPreview img").attr("src", e.target.result);
$("#dvPreview img").attr('width', '250px'); // change width.
$("#dvPreview img").attr('height', '250px'); // change height.
}
reader.readAsDataURL($(this)[0].files[0]);
} else {
alert("This browser does not support FileReader.");
}
}
} else {
alert("Please upload a valid image file.");
}
});
});
</script>
<style type="text/css">
#dvPreview
{
filter: progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=image);
min-height: 400px;
min-width: 400px;
display: none;
}
</style>
</form>
</body>
</html>
Demo
