I was inspired by this post https://goo.gl/iAtDo3 and I've migrated it to .Net Standard using Xamarin Forms 3.3 with MVVMLightStd and Cognitive Service Computer Vision
Dallas411/XFormsMvvmLightCVision
A Xamarin Forms DotNet Std solution using MvvmLight to develops a Cognitive Service Cumputer Vision sample
C#