ImageProcessing

using System;
using System.Drawing;
using System.IO;
using System.Net.Mime;

namespace imageProcess
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Hello World!");
            var filePath = @"D:\code\imageProcess\picture.JPG";

            var bitmap = GetBitmap(filePath);


            var newBitmap = new Bitmap(bitmap.Width/2, bitmap.Height / 2);

            var indexI = 0;
            var indexJ = 0;

            for (int i = 0; i < newBitmap.Width; i++)
            {
                indexJ = 0;
                for (int j = 0; j < newBitmap.Height; j++)
                {
                    var pixel00 = bitmap.GetPixel(indexI, indexJ);
                    var pixel01 = bitmap.GetPixel(indexI, indexJ + 1);
                    var pixel10 = bitmap.GetPixel(indexI + 1, indexJ);
                    var pixel11 = bitmap.GetPixel(indexI + 1, indexJ + 1);

                    var A = (pixel00.A + pixel01.A + pixel10.A + pixel11.A) / 4;
                    var R = (pixel00.R + pixel01.R + pixel10.R + pixel11.R) / 4;
                    var G = (pixel00.G + pixel01.G + pixel10.G + pixel11.G) / 4;
                    var B = (pixel00.B + pixel01.B + pixel10.B + pixel11.B) / 4;

                    //newBitmap.SetPixel(i, j, Color.FromArgb(A,R,G,B));

                    if (((R + G + B) / 3) > 127)
                        newBitmap.SetPixel(i, j, Color.FromArgb(A, 255, 0, 0));
                    else
                        newBitmap.SetPixel(i, j, Color.FromArgb(A, 0, 0, 0));
                    indexJ += 2;
                }
                indexI += 2;
            }

            newBitmap.Save("new.bmp");
        }

        static System.Drawing.Bitmap GetBitmap(string filePath)
        {
            Bitmap bitmap;
            
            using(Stream stream = File.Open(filePath, System.IO.FileMode.Open))
            {
                Image image = Image.FromStream(stream);
                bitmap = new Bitmap(image);
            }

            return bitmap;
        }
    }
}