Here's a nice way to bind to mouse events to a RoutedCommand. My RoutedCommand is defined in a ViewModel (in the Model-View-ViewModel pattern):

<Image Name="Image" Grid.Row="0"
           Source="{Binding DataModel.Thumbnail, Converter={StaticResource
                        ImageConverter}}">
    <Image.InputBindings>
        <MouseBinding MouseAction="LeftDoubleClick"
                            Command="vm:ThumbnailViewModel.PreviewCommand"/>
    </Image.InputBindings>
</Image>