﹤Grid x:Name="LayoutRoot"﹥

  ﹤Image x:Name="MyBitmap"

  Width="200"

  Height="200" /﹥

  ﹤/Grid﹥

private void BuildBitmap()
{
const int imageWidth = 200;
const int imageHeight = 200;

WriteableBitmap b =
new WriteableBitmap(imageWidth, imageHeight,
PixelFormats.Bgr32);

b.Lock();

for (int x = 0; x ﹤ imageWidth; x++)
{
for (int y = 0; y ﹤ imageHeight; y++)
{
// generate a color in Pbgra32 format
byte[] components = new byte[4];
components[0] = (byte)(x % 255); // blue
components[1] = (byte)(y % 255); // green
components[2] = (byte)(x * y % 255); // red
components[3] = 0; // unused

// you could certainly do your own masking here
int pixelValue = BitConverter.ToInt32(components, 0);

// set the pixel value
b[y * imageWidth + x] = pixelValue;
}
}

b.Invalidate();
b.Unlock();

MyBitmap.Source = b;

}