图像的灰度和黑白处理算法

偶尔找一个图像转化的算法，试了试不错。

效果图：

 (原图)

(处理处理)

(黑白处理)

代码：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;


namespace ConsoleApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }


        Color GrayT(Color c)
        {
            int rgb = Convert.ToInt32((double)(0.3 * c.R + 0.59 * c.G + 0.11 * c.B));
            return Color.FromArgb(rgb, rgb, rgb);
 
        }

        void Binarizate(Bitmap map)
        {
            int tv = ComputeThresholdValue(map);
            int x = map.Width;
            int y = map.Height;
            for (int i = 0; i < x; i++)
            {
                for(int j=0; j < y;j++)
                {
                    if (map.GetPixel(i, j).R >= tv)
                    {

                        map.SetPixel(i, j, Color.FromArgb(0xff, 0xff, 0xff));
                    }
                    else
                    {
                        map.SetPixel(i, j, Color.FromArgb(0, 0, 0)); 
                    }
                }
            }
        }

        int ComputeThresholdValue(Bitmap map)
        {
            int i;
            int k;
            double csum;
            int thresholdValue = 1;
            int[] iHist = new int[0x100];
            for (i = 0; i < 0x100; i++)
            {
                iHist[i] = 0;
            }

            int gmin = 0xff;
            int gmax = 0;

            for (i = 1; i < map.Width - 1; i++)
            {
                for (int j = 1; j < map.Height - 1; j++)
                {
                    int cn = map.GetPixel(i, j).R;
                    iHist[cn]++;
                    if (cn > gmax)
                        gmax = cn;
                    if (cn < gmin)
                        gmin = cn;
                }
            }

            double sum = csum = 0.0;
            int n = 0;
            for (k = 0; k < 0xff; k++)
            {
                sum += k * iHist[k];
                n += iHist[k];
            }

            if (n == 0) 
            {
                return 60;
            }

            double fmax = -1.0;
            int n1 = 0;
            for (k = 0; k < 0xff; k++)
            {
                n1 += iHist[k];
                if (n1 != 0)
                {
                    int n2 = n - n1;
                    if (n2 == 0)
                    {
                        return thresholdValue;
                    }

                    csum += k * iHist[k];
                    double m1 = csum / ((double)n1);
                    double m2 = (sum - csum) / ((double)n2);
                    double sb = ((n1 * n2) * (m1 - m2)) * (m1 - m2);
                    if (sb > fmax)
                    {
                        fmax = sb;
                        thresholdValue = k;
                    }

                }

            }
            return thresholdValue;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string path = @"C:\Documents and Settings\v-jimsom\My Documents\Visual Studio 2008\Projects\ConsoleApplication1\ConsoleApplication1\";
            string mapPath = path + @"Image\untitled.bmp";
            string grayPath = path + @"Image\untitled1.bmp";
            string bitPath = path + @"Image\untitled2.bmp";
            Image map = Bitmap.FromFile(mapPath);
            Bitmap bitmap = new Bitmap(map);

            //Gray the bitmap

            for (int i = 0; i < bitmap.Width; i++)
            {
                for (int j = 0; j < bitmap.Height; j++)
                {
                    Color cc = bitmap.GetPixel(i, j);
                    bitmap.SetPixel(i, j, GrayT(cc));
                }
            }

            if (File.Exists(grayPath))
            {
                File.Delete(grayPath);
            }
            bitmap.Save(grayPath);

            this.pictureBox1.Image = Bitmap.FromFile(grayPath);

            //binarizata the bitmap

            Binarizate(bitmap);
            if (File.Exists(bitPath))
            {
                File.Delete(bitPath);
            }
            bitmap.Save(bitPath);

            this.pictureBox1.Image = Bitmap.FromFile(bitPath);
            
        }
    }
}