c#实现图片二值化例子（黑白效果）

C#将图片2值化示例代码，原图及二值化后的图片如下：

原图：

二值化后的图像：

实现代码：

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93

using System; using System.Drawing; namespace BMP2Grey {   class Program   {     static void ToGrey(Bitmap img1)     {       for (int i = 0; i < img1.Width; i++)       {         for (int j = 0; j < img1.Height; j++)         {           Color pixelColor = img1.GetPixel(i, j);           //计算灰度值           int grey = (int)(0.299 * pixelColor.R + 0.587 * pixelColor.G + 0.114 * pixelColor.B);           Color newColor = Color.FromArgb(grey, grey, grey);           img1.SetPixel(i, j, newColor);         }       }     }     static void Thresholding(Bitmap img1)     {       int[] histogram = new int[256];       int minGrayValue=255, maxGrayValue=0;       //求取直方图       for (int i = 0; i < img1.Width; i++)       {         for (int j = 0; j < img1.Height; j++)         {           Color pixelColor = img1.GetPixel(i, j);           histogram[pixelColor.R]++;           if (pixelColor.R > maxGrayValue) maxGrayValue = pixelColor.R;           if (pixelColor.R < minGrayValue) minGrayValue = pixelColor.R;         }       }       //迭代计算阀值       int threshold = -1;       int newThreshold = (minGrayValue + maxGrayValue) / 2;       for(int iterationTimes = 0; threshold != newThreshold && iterationTimes < 100; iterationTimes++)       {         threshold = newThreshold;         int lP1 =0;         int lP2 =0;         int lS1 = 0;         int lS2 = 0;         //求两个区域的灰度的平均值         for (int i = minGrayValue;i < threshold;i++)         {           lP1 += histogram[i] * i;           lS1 += histogram[i];         }         int mean1GrayValue = (lP1 / lS1);         for (int i = threshold+1;i < maxGrayValue;i++)         {           lP2 += histogram[i] * i;           lS2 += histogram[i];         }         int mean2GrayValue = (lP2 / lS2);         newThreshold = (mean1GrayValue + mean2GrayValue) / 2;       }       //计算二值化       for (int i = 0; i < img1.Width; i++)       {         for (int j = 0; j < img1.Height; j++)         {           Color pixelColor = img1.GetPixel(i, j);           if (pixelColor.R > threshold) img1.SetPixel(i, j, Color.FromArgb(255, 255, 255));           else img1.SetPixel(i, j, Color.FromArgb(0, 0, 0));         }       }     }     static void Main(string[] args)     {       try       {         //打开位图文件         Bitmap img1 = new Bitmap("test.jpg", true);         //灰度化         ToGrey(img1);         //二值化         Thresholding(img1);         //写回位图文件         img1.Save("output.jpg");         Console.WriteLine("Converted.");       }       catch (ArgumentException)       {         Console.WriteLine("Invalid usage!");         Console.WriteLine("Usage: bmp2grey source object");       }     }   } }