This way:
HTML:
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
<script type="text/javascript">
function PrintPanel() {
var panel = document.getElementById("<%=pnlContents.ClientID %>");
var printWindow = window.open('', '', 'height=400,width=800');
printWindow.document.write('<html><head><title>DIV Contents</title>');
printWindow.document.write('</head><body >');
printWindow.document.write(panel.innerHTML);
printWindow.document.write('</body></html>');
printWindow.document.close();
setTimeout(function () {
printWindow.print();
}, 500);
return false;
}
</script>
</head>
<body>
<form id="form1" runat="server">
<div id="pnlContents" runat="server" style="display: none;">
<img src="../images/Abc.jpg" />
</div>
<br />
<asp:Button ID="btnPrint" runat="server" Text="Print" OnClientClick="return PrintPanel();" />
</form>
</body>
</html>
Thank You.