Display an image stored locally

Hello,
I am trying to display an image stored locally under a PCL library and using Xamarin.Forms with in MyPage.xaml:

< Image x:Name="MyImage" / >

And code:

InitializeComponent();
MyImage.Source = ImageSource.FromUri(new Uri("file:///C:/Users/Administrateur/Pictures/img1.jpg"));

But without success (nothing is display).
Can someone know what is wrong? Thanks.