How add border to a RGB image - Add black border to RGB image

using Aurigma.GraphicsMill;
using Aurigma.GraphicsMill.Codecs;
using Aurigma.GraphicsMill.Transforms;

class Program
{
	static void Main(string[] args)
	{
		var borderColor = RgbColor.Blue;
		int borderWidth = 20;

		using (var reader = ImageReader.Create("../../../test.png"))
		using (var generator = new ImageGenerator(reader.Width + borderWidth * 2,  
			reader.Height + borderWidth * 2, reader.PixelFormat, borderColor))
		using (var blender = new Blender())
		using (var writer = ImageWriter.Create("../../../out.png"))
		{
			blender.TopImage = reader;
			blender.X = borderWidth;
			blender.Y = borderWidth;

			(generator + blender + writer).Run();
		}
	}
}

private void button1_Click(object sender, EventArgs e)
        {
            var borderColor = RgbColor.Black;
            int borderWidth = 20;
            
            using (var reader = new TiffReader("E:/TEST/INTIFF/001.tif")) // big image at 400dpi
            using (var generator = new ImageGenerator(reader.Width + borderWidth * 2, reader.Height + borderWidth * 2, reader.PixelFormat, borderColor))
            using (var blender = new Blender())
            using (var writer = new TiffWriter("E:/TEST/INTIFF/out.tif"))
            
            {
                var exif = reader.Exif;
                writer.Exif = exif;
                blender.TopImage = reader;
                blender.X = borderWidth;
                blender.Y = borderWidth;
                Pipeline.Run(generator + blender + writer);
                //(generator + blender + writer).Run();
            }
        }