New Post: vignette effect

At this moment it is not possible. With changeset 26420 I resolved this issue but you have to wait for the next release (prob. next week) before you can use it.

I am not sure if this gives you the same result but it should be something like this:

using (MagickImageCollection images = new MagickImageCollection())
{
  MagickReadSettings settings = new MagickReadSettings();
  settings.Width = 960;
  settings.Height = 960;
  
  MagickImage radialGradient = new MagickImage("radial-gradient:none-black", settings);
  radialGradient.Crop(640, 640, Gravity.Center);
  images.Add(radialGradient);
  
  MagickImage input = new MagickImage("input.jpg");
  input.Compose = CompositeOperator.Multiply;
  images.Add(input);
  
  images.RePage();
  
  using (MagickImage output = images.Merge(LayerMethod.Flatten))
  {
    output.Write("output.jpg");
  }
}