{
        FileOpenPicker openPicker = new FileOpenPicker(); //Открываю изображение
        openPicker.ViewMode = PickerViewMode.Thumbnail;
        openPicker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;
        openPicker.FileTypeFilter.Add(".jpg");
        openPicker.FileTypeFilter.Add(".jpeg");
        openPicker.FileTypeFilter.Add(".png");
        StorageFile file = await openPicker.PickSingleFileAsync();
        if (file != null)
        {
            if (file != null)
            {
                using (IRandomAccessStream fileStream = await file.OpenAsync(Windows.Storage.FileAccessMode.Read))
                {

                    //преобразую поток в байтовый массив
                    byte[] fileBytes;
                    using (var Stream = await file.OpenStreamForReadAsync())
                    {
                        var binaryReader = new BinaryReader(Stream);
                        fileBytes = binaryReader.ReadBytes((int)Stream.Length);
                    }

                    using (var client = new HttpClient())
                    {

                        var apiUri = new Uri("Некий.Хостинг.php");

                        var imageBinaryContent = new ByteArrayContent(fileBytes);

                        var multipartContent = new MultipartFormDataContent();
                        multipartContent.Add(imageBinaryContent, "image" );

                        var result = await client.PostAsync(apiUri, multipartContent);
                        Name.Text = result.Content.ReadAsStringAsync().Result;
                    }
                }
            }
        }
        else
        {
            Name.Text = "Operation cancelled.";
        }
    }