convert this image into black and white but getting some issue

[AshaRxKhan]

Hello
I am trying to convert this image magick command into c# code.
D:/input.png +dither -colors 256 -normalize -flatten -monochrome +compress D:/output.png
input file

expected output

QuantizeSettings settings = new QuantizeSettings();

        settings.DitherMethod = DitherMethod.No;
         settings.Colors = 256;
        
         MagickImageCollection magickImageCollection = new MagickImageCollection();
         MagickReadSettings magickReadSettings = new MagickReadSettings();
        //magickReadSettings.UseMonochrome = false;
         MagickImage image = new MagickImage(intput, magickReadSettings);
         
         image.Quantize(settings);

         image.Normalize();
         image.Write(output);
         magickImageCollection.Read((output));
         image = (MagickImage)magickImageCollection.Flatten();
        image.ColorType = ColorType.Bilevel;
       image.Settings.Compression=CompressionMethod.NoCompression;
     
         image.Write(output");

    }
    **output after c# conversion**

[dlemstra]

Sorry for the late response but are you using the same version of ImageMagick as Magick.NET?