How To: Do image comparison in Coded UI Test

http://blogs.msdn.com/b/gautamg/archive/2010/04/08/how-to-do-image-comparison-in-coded-ui-test.aspx

[TestMethod]
[DeploymentItem("Master.png")]
[DeploymentItem("ToleranceMap.png")]
[DeploymentItem("SampleApp.exe")]
public void CompareImagesTest()
{
    // Launch the application.
    using (ApplicationUnderTest app = ApplicationUnderTest.Launch(
                Path.Combine(Directory.GetCurrentDirectory(),
                "SampleApp.exe")))
    {
        // Select the check box, so that the background will change.
        WpfCheckBox checkBox = new WpfCheckBox(app);
        checkBox.Checked = true;

        // Get the actual, master and toleracne snapshots.
        Snapshot toleranceMap =
                Snapshot.FromFile("ToleranceMap.png");
        Snapshot master = Snapshot.FromFile("Master.png");
        Snapshot actual = Snapshot.FromWindow(app.WindowHandle,
                WindowSnapshotMode.ExcludeWindowBorder);

        // Get the difference of two images.
        Snapshot difference = actual.CompareTo(master);

        // Save the file to for manual viewing.
        master.ToFile(@"Master-expected.png", ImageFormat.Png);
        actual.ToFile(@"Master-actual.png", ImageFormat.Png);
        difference.ToFile(@"Master-difference.png",
                            ImageFormat.Png);

        // Use SnapshotToleranceMapVerifier to verify the comparison.
        SnapshotVerifier verifier =
                new SnapshotToleranceMapVerifier(toleranceMap);
        Assert.AreEqual(VerificationResult.Pass,
                verifier.Verify(difference));