如何让 XAML 中的图像显示为实际大小？

我有一个27 x 27我在 WPF 中显示的像素图像，但它显示larger比大小window.

如何让它显示实际尺寸？

替代文本 http://www.deviantsart.com/upload/m20dk6.png http://www.deviantsart.com/upload/m20dk6.png

XAML:

<Window x:Class="TestImage23434.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1" Height="300" Width="300">
    <StackPanel x:Name="MainStackPanel"/>
</Window>

背后代码：

using System.Windows;
using System.Windows.Controls;
using System.Windows.Media.Imaging;
using System;

namespace TestImage23434
{
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();

            TextBlock tb = new TextBlock();
            tb.Text = "above image ";
            MainStackPanel.Children.Add(tb);

            Image img = new Image();
            img.Source = new BitmapImage(new Uri(@"C:\test\circle.png"));
            img.HorizontalAlignment = HorizontalAlignment.Left;
            img.VerticalAlignment = VerticalAlignment.Top;
            MainStackPanel.HorizontalAlignment = HorizontalAlignment.Left;
            MainStackPanel.VerticalAlignment = VerticalAlignment.Top;
            MainStackPanel.Children.Add(img);

            TextBlock tb2 = new TextBlock();
            tb2.Text = "below image";
            MainStackPanel.Children.Add(tb2);
        }
    }
}

img.Stretch = Stretch.None

默认情况下，拉伸性能 http://msdn.microsoft.com/en-us/library/system.windows.media.stretch.aspx值为Uniform，它会调整图像大小以填充所有可用空间。