using System;
using System.Drawing;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        Timer t1 = new Timer();
        Bitmap bmp = new Bitmap(@"D:\img.png");
        Bitmap outputImage;

        public Form1()
        {
            InitializeComponent();

            pictureBox1.Image = bmp;

            t1.Tick += new EventHandler(t1_Tick);
            t1.Interval = 100;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            outputImage = new Bitmap(bmp);
            x = 0;
            y = 0;

            t1.Start();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            pictureBox2.Image = toGreyscale(bmp);
        }

        private Bitmap toGreyscale(Bitmap source)
        {
            Bitmap outputImage = new Bitmap(source);

            for (int y = 0; y < source.Height; y++)
            {
                for (int x = 0; x < source.Width; x++)
                {
                    int r, g, b;

                    r = source.GetPixel(x, y).R;
                    g = source.GetPixel(x, y).G;
                    b = source.GetPixel(x, y).B;

                    int greyscale = (r + g + b) / 3;

                    Color greyscalecolor = new Color();
                    greyscalecolor = Color.FromArgb(greyscale, greyscale, greyscale);

                    outputImage.SetPixel(x, y, greyscalecolor);
                }
            }
            return outputImage;
        }

        int x, y;
        int r, g, b;
        int greyscale;
        Color greyscalecolor = new Color();

        void t1_Tick(object sender, EventArgs e)
        {
            if (x < bmp.Width)
            {
                r = bmp.GetPixel(x, y).R;
                g = bmp.GetPixel(x, y).G;
                b = bmp.GetPixel(x, y).B;

                greyscale = (r + g + b) / 3;

                greyscalecolor = Color.FromArgb(greyscale, greyscale, greyscale);

                outputImage.SetPixel(x, y, greyscalecolor);
                pictureBox2.Image = outputImage;
                pictureBox2.Refresh();

                x++;

                if (x >= bmp.Width)
                {
                    y++;
                    x = 0;
                }
            }
        }
    }
}