这里怎么把VALUE的值设置成图片路径

 <VisualState x:Name="Disabled">
                                            <Storyboard>
                                                <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="ContentContainer">
                                                    <DiscreteObjectKeyFrame KeyTime="0" Value="Black"/>
                                                </ObjectAnimationUsingKeyFrames>
                                                <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="BorderBrush" Storyboard.TargetName="ButtonBackground">
                                                    <DiscreteObjectKeyFrame KeyTime="0" Value="Black"/>
                                                </ObjectAnimationUsingKeyFrames>
                                                <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="ButtonBackground">
                                                    <DiscreteObjectKeyFrame KeyTime="0" Value="/Assets/getcode.png" />//这里如何把VALUE的值设置成图片路径
                                                </ObjectAnimationUsingKeyFrames>
                                            </Storyboard>
                                        </VisualState>