Ancho y alto BMP, BinaryReader Aprende programación con ejercicios C# Sharp

using System;
using System.IO;
public class BmpHeightWidth
{
    public static void Main()
    {
        BinaryReader myFile;
        byte b1, b2;
        int width, height;

        myFile = new BinaryReader(
            File.Open("example.bmp", FileMode.Open));
        b1 = myFile.ReadByte();
        b2 = myFile.ReadByte();

        if ((b1 == 0x42) && (b2 == 0x4D))
        {
            Console.WriteLine("It seems to be a BMP file");
            myFile.BaseStream.Seek(18, SeekOrigin.Begin);
            width = myFile.ReadInt32();
            height = myFile.ReadInt32();
            Console.WriteLine("Width: {0} pixels", width);
            Console.WriteLine("Height: {0} pixels", height);
        }
        else
            Console.WriteLine("It DOES NOT seem to be a BMP file");

        myFile.Close();
    }
}