如何从pixeldata和调色板构建indexed8位图

我正在尝试使用指定的调色板创建3x1位图。为了测试,我使用了三种颜色:红色、绿色和蓝色。当我运行代码时,我得到的都是红色(这是第一种颜色)。

这是我的密码

public void CreateTestImg()
{
    // List to store colors for palette
    List<Color> Colors = new List<Color>();
    // Adds Red to the list
    Colors.Add(Media.Color.FromArgb(255, 255, 0, 0));
    // Adds Green to the list
    Colors.Add(Media.Color.FromArgb(255, 0, 255, 0));
    // Adds Blue to the list
    Colors.Add(Media.Color.FromArgb(255, 0, 0, 255));
    // Create a new palette with the list of colors as input
    BitmapPalette PLT = new BitmapPalette(Colors);
    // Make a Bitmap with the specified width, height, dpix, dpiy, pixelformat, palette, PixelData, stride.
    BitmapSource wb = BitmapSource.Create(3, 1, 96, 96, PixelFormats.Indexed8, PLT, {0, 1, 2}, 3);
    // Freezes the object
    wb.Freeze();
    // Creates a new brush from the Bitmap so I can draw with it later
    ImageBrush newBMB = new ImageBrush(wb);
    // Freezes the brush
    newBMB.Freeze();
    // Adds brush to dictionary for later referencing
    ImageBatch.Add("WHATEVER", newBMB);
}