WPF C＃图像亮度

Question

我将Image加载到BitmapImage。

XAML

<Image Margin="12,12,16,71" Name="imgPhoto">

Code behind

OpenFileDialog op = new OpenFileDialog();
op.Title = "Select a picture";
op.Filter = "All supported graphics|*.jpg;*.jpeg;*.png|" +
                "JPEG (*.jpg;*.jpeg)|*.jpg;*.jpeg|" +
                "Portable Network Graphic (*.png)|*.png";

if (op.ShowDialog() == true)
{
    imgPhoto.Source = new BitmapImage(new Uri(op.FileName));
}

如何更改此Image的亮度？