Convert 'Xamarin.Form.Image' type 'byte[]'

Hi All

i am suppose to get an Image from url and convert it into byte[]. The following is what I achieved

var webImage = new Image { Aspect = Aspect.AspectFit };
webImage.Source = ImageSource.FromUri(new Uri("http://xamarin.com/content/images/pages/forms/example-app.png"));

but now I am unable to convert Image type to byte[]

Is this the correct way to approach. Any kind of help would be apprciated.