How To Upload Only Image File In Asp.net c#

Upload Only Image File In Asp.net

First Of All 
We Need Three controls

1 FileUpload

2 RequiredFieldValidator

3 RegularExpressionValidator



<asp:FileUpload ID="image" class="lbl" runat="server" Width="160px" />

                        
<asp:RequiredFieldValidator
 ID="RequiredFieldValidator10"
 runat="server" 
ControlToValidate="image"
 ValidationGroup="register"
 ErrorMessage="*">
</asp:RequiredFieldValidator>
                         
<asp:RegularExpressionValidator
 ID="RegularExpressionValidator2"
 ForeColor="red" 
ControlToValidate="image"
 runat="server"
 ErrorMessage="Select valid Image "
 ValidationExpression="([a-zA-Z0-9\s_\\.\-:])+(.png|.jpg|.gif)$">
</asp:RegularExpressionValidator>