WPF

<Window 
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
  <Window.BitmapEffect>
    <BlurBitmapEffect x:Name="blurTarget" KernelType="Gaussian" Radius="0"/>
  </Window.BitmapEffect>
  <Window.Triggers>
    <EventTrigger RoutedEvent="Window.Loaded">
      <BeginStoryboard>
        <Storyboard>
          <DoubleAnimation
            Duration="0: 0:10"
            From="0.0"
            Storyboard.TargetName="blurTarget"
            Storyboard.TargetProperty="Radius"
            To="40.0"/>
        </Storyboard>
      </BeginStoryboard>
    </EventTrigger>
  </Window.Triggers>
  <Grid>
    <Button Content="This Is my button" />
  </Grid>
</Window>

Storyboard storyBlur = this.FindResource("blurMainWindow") as Storyboard;
storyBlur.Begin();

<BlurEffect x:Name="blurTarget" Radius="12" KernelType="Gaussian" />
<Storyboard x:Key="AnimateUnblur">
    <DoubleAnimation From="12" To="0" Duration="0:0:1"
                        Storyboard.TargetName="blurTarget"
                        Storyboard.TargetProperty="Radius" />
</Storyboard>

BlurEffect blur = (BlurEffect)FindResource("blurTarget");
this.Effect     = blur;

Mark Salsbery wrote:

The UriKind should be Absolute as well.

paradisonoir wrote:

> string location = @"C:\myPhoto.png";

> Uri uri= new Uri(location,> UriKind.Relative);