Hello Everyone,
Here is simple sample how to apply Brightness/Contrast without Roundtrip using
remote scripting approach.
Here is screenshot:

And here is code:
Code:<%@ Page language="VB" AutoEventWireup="false" %>
<%@ Register TagPrefix="cc1" Namespace="Aurigma.GraphicsMill.WebControls" Assembly="Aurigma.GraphicsMill.WebControls" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" >
<html>
<head>
<title>WebForm1</title>
<script runat="server" language="VB">
Private imagePath As String = "TestImages/2.jpg"
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
If Not Page.IsPostBack Then
BitmapViewer1.Bitmap.Load(Server.MapPath(imagePath))
End If
End Sub
<RemoteScriptingMethod> _
Public Sub BrightnessContrast(brightness As Single, contrast As Single)
'Reload image as image could be already changed
BitmapViewer1.Bitmap.Load(Server.MapPath(imagePath))
BitmapViewer1.Bitmap.ColorAdjustment.BrightnessContrast(brightness, contrast)
End Sub
</script>
<script>
function brightnessContrast_change(){
//Brightness value
var b=document.getElementById("brightness");
var bValue=b.options[b.selectedIndex].value/100;
//Contrast value
var c=document.getElementById("contrast");
var cValue=c.options[c.selectedIndex].value/100;
var bitmapViewer1=document.getElementById("<%=BitmapViewer1.ClientID%>");
bitmapViewer1.invokeRemoteMethod("BrightnessContrast", new Array(bValue, cValue))
}
</script>
</head>
<body MS_POSITIONING="GridLayout">
<form id="Form1" method="post" runat="server">
Brightness:
<select id="brightness" onchange="brightnessContrast_change();">
<option value="100">+100</option>
<option value="75">+75</option>
<option value="50">+50</option>
<option value="25">+25</option>
<option value="0" selected>0</option>
<option value="-25">-25</option>
<option value="-50">-50</option>
<option value="-75">-75</option>
<option value="-100">-100</option>
</select>
Contrast:
<select id="contrast" onchange="brightnessContrast_change();">
<option value="100">+100</option>
<option value="75">+75</option>
<option value="50">+50</option>
<option value="25">+25</option>
<option value="0" selected>0</option>
<option value="-25">-25</option>
<option value="-50">-50</option>
<option value="-75">-75</option>
<option value="-100">-100</option>
</select>
<cc1:BitmapViewer id="BitmapViewer1" runat="server" Width="400px" Height="300px">
</cc1:BitmapViewer>
</form>
</body>
</html>
To speed up process it makes sense to set
BitmapStateEnabled=
false, as well as apply effects on small preview during editing.
Fedor attached the following image(s):

Best regards,
Fedor Skvortsov