Image from Xamarin.Forms.Image

Hi everyone my problem is that I need to get the image (data or byte[]) from a Xamarin.Forms.Image actually my Image.Source can be setted by Stream(Here I implemented the example that xamarin provides to open the gallery) or by an Uri and then I need to send this data by Http Request Multipartdata(I have an implementation of this but with the image converted to byte[])
I have my Xamarin.Forms.Image in my ViewModel.
Thanks.