TakePicker.txt

//ui
    <Button
        android:id="@+id/MyButton"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="Pick Image" />
    <ImageView
        android:src="@android:drawable/ic_menu_gallery"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:id="@+id/imageView1" />

//code

   public static readonly int PickImageId = 1000;
        private ImageView _imageView;
        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);

            // Set our view from the "main" layout resource
            SetContentView(Resource.Layout.Main);

            _imageView = FindViewById<ImageView>(Resource.Id.imageView1);
            Button button = FindViewById<Button>(Resource.Id.MyButton);
            button.Click += ButtonOnClick;
        }
        private void ButtonOnClick(object sender, EventArgs eventArgs)
        {
            Intent = new Intent();
            Intent.SetType("image/*");
            Intent.SetAction(Intent.ActionGetContent);
            StartActivityForResult(Intent.CreateChooser(Intent, "Select Picture"), PickImageId);
        }
        protected override void OnActivityResult(int requestCode, Result resultCode, Intent data)
        {
            if ((requestCode == PickImageId) && (resultCode == Result.Ok) && (data != null))
            {
              
                _imageView.SetImageURI(data.Data);
            }
        }