private async void callAzureFunction2CommandExecute()
        {
            Windows.Storage.Pickers.FileOpenPicker picker = new Windows.Storage.Pickers.FileOpenPicker();
            picker.CommitButtonText = "OK";
            picker.FileTypeFilter.Add(".jpg");
            picker.FileTypeFilter.Add(".jpeg");
            picker.FileTypeFilter.Add(".png");
            picker.SuggestedStartLocation = Windows.Storage.Pickers.PickerLocationId.PicturesLibrary;
            var file = await picker.PickSingleFileAsync();

            if (file != null)
            {
                this.Wait      = true;
                this.ImageFile = file.Path;
                var buffer = await FileIO.ReadBufferAsync(file);

                byte[] bytes = buffer.ToArray();

                string code     = "f3RuUGE2BM8UjjA0XJ8g6br/eDP9L3NsG1n3MR8ZYfbipRiHQ0XiJg==";
                string url      = "https://visualstudiotips.azurewebsites.net/api/GetImageColors?code=" + code;
                var    response = await client.PostAsync(url, new ByteArrayContent(bytes));

                if (response.IsSuccessStatusCode)
                {
                    var json = await response.Content.ReadAsAsync <string>();

                    imageColors = JsonConvert.DeserializeObject <ImageColors>(json);
                    base.RaisePropertyChanged(nameof(RedPercentage));
                    base.RaisePropertyChanged(nameof(GreenPercentage));
                    base.RaisePropertyChanged(nameof(BluePercentage));
                }

                this.Wait = false;
            }
        }
        /// <summary>
        /// process update image to grayscale request
        /// </summary>
        private string updateGrayscale(string imageFile)
        {
            ImageColors updateImageColor = new ImageColors();

            return(updateImageColor.UpdateImagetoGrayscale(imageFile));
        }