四   指针法 C/C++的习惯,不是C#的特点 public static Bitmap  RGB2Gray(Bitmap srcBitmap)         {             int wide = srcBitmap.Width;             int height = srcBitmap.Height ;             Rectangle rect = new Rectangle(0, 0, wide, height);             BitmapData srcBmData = srcBitmap.LockBits(rect,                       ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);             Bitmap dstBitmap = CreateGrayscaleImage(wide, height);             BitmapData dstBmData = dstBitmap.LockBits(rect,                       ImageLockMode.ReadWrite, PixelFormat.Format8bppIndexed);                 System.IntPtr srcScan = srcBmData.Scan0;             System.IntPtr dstScan = dstBmData.Scan0;             Unsafe  //启动不安全代码             {                 byte* srcP = (byte*)(void*) srcScan;                 byte* dstP = (byte*)(void*) dstScan;                 int srcOffset = srcBmData.Stride - wide  * 3;                 int dstOffset = dstBmData.Stride  - wide ;                 byte red, green, blue;                 for (int y = 0; y < height; y++)                 {                     for (int x = 0; x <wide ; x++, srcP += 3, dstP++)                     {                         blue = srcP [0];                         green = srcP [1];                         red = srcP [2];                         * dstP = (byte)(.299 * red + .587 * green + .114 * blue);                                             }                     srcP += srcOffset;                     dstP += dstOffset;                 }             }             srcBitmap.UnlockBits(srcBmData);             dstBitmap.UnlockBits(dstBmData );             return dstBitmap;           }//# 五.   矩阵法 并不是什么新方法,只是将图像数据分做R,G,B三个矩阵(二维数组)存储,类似MATLAB的习惯.        public static bool GetRGB(Bitmap Source, out int[,] R, out int[,] G, out int[,] B)         {             try             {                 int iWidth = Source.Width;                 int iHeight = Source.Height;                   Rectangle rect = new Rectangle(0, 0, iWidth, iHeight);                 System.Drawing.Imaging.BitmapData bmpData = Source.LockBits(rect, System.Drawing.Imaging.ImageLockMode.ReadWrite, Source.PixelFormat);                 IntPtr iPtr = bmpData.Scan0;                   int iBytes = iWidth * iHeight * 3;                 byte[] PixelValues = new byte[iBytes];                 System.Runtime.InteropServices.Marshal.Copy(iPtr, PixelValues, 0, iBytes);                 Source.UnlockBits(bmpData);                   // 注意这个地方图像的两维方向与数组两维的方向是转置的关系                   R = new int[iHeight, iWidth];                 G = new int[iHeight, iWidth];                 B = new int[iHeight, iWidth];                   int iPoint = 0;                   for (int i = 0; i < iHeight; i++)                 {                     for (int j = 0; j < iWidth; j++)                     {                         // 注意，Windows 中三基色的排列顺序是 BGR 而不是 RGB！                         B[i, j] = Convert.ToInt32(PixelValues[iPoint++]);                         G[i, j] = Convert.ToInt32(PixelValues[iPoint++]);                         R[i, j] = Convert.ToInt32(PixelValues[iPoint++]);                     }                 }                   return true;             }             catch (Exception)             {                 R = null;                 G = null;                 B = null;                   return false;             }         }//#         public static Bitmap FromRGB(int[,] R, int[,] G, int[,] B)         {             int iWidth = G.GetLength(1);             int iHeight = G.GetLength(0);             Bitmap Result = new Bitmap(iWidth, iHeight, System.Drawing.Imaging.PixelFormat.Format24bppRgb);               Rectangle rect = new Rectangle(0, 0, iWidth, iHeight);             System.Drawing.Imaging.BitmapData bmpData = Result.LockBits(rect, System.Drawing.Imaging.ImageLockMode.ReadWrite, System.Drawing.Imaging.PixelFormat.Format24bppRgb);             IntPtr iPtr = bmpData.Scan0;             int iStride = bmpData.Stride;               int iBytes = iWidth * iHeight * 3;             byte[] PixelValues = new byte[iBytes];               int iPoint = 0;               for (int i = 0; i < iHeight; i++)                 for (int j = 0; j < iWidth; j++)                 {                     int iG = G[i, j];                     int iB = B[i, j];                     int iR = R[i, j];                     PixelValues[iPoint] = Convert.ToByte(iB);                     PixelValues[iPoint + 1] = Convert.ToByte(iG);                     PixelValues[iPoint + 2] = Convert.ToByte(iR);                     iPoint += 3;                 }               System.Runtime.InteropServices.Marshal.Copy(PixelValues, 0, iPtr, iBytes);               Result.UnlockBits(bmpData);               return Result;         }//#         public static bool  GetGray(Bitmap srcBitmap, out byte [,] gray)         {               Bitmap tempBitmap;             if (srcBitmap.PixelFormat != PixelFormat.Format8bppIndexed)                 tempBitmap = ImageProcess.Image.Gray(srcBitmap);             else                 tempBitmap = srcBitmap;             int wide = tempBitmap.Width;             int height = tempBitmap.Height;             gray = new byte [height, wide];             BitmapData gbmData = tempBitmap.LockBits(new Rectangle(0, 0, wide, height),                   ImageLockMode.ReadWrite, PixelFormat.Format8bppIndexed);             System.IntPtr ScanG = gbmData.Scan0;             int gOffset = gbmData.Stride - wide;             unsafe             {                 byte* g = (byte*)(void*)ScanG;                 // for each pixel                 for (int y = 0; y < height; y++)                 {                     // for each pixel                     for (int x = 0; x < wide; x++, g++)                     {                         gray[y ,x ] =*g;                     }                     g += gOffset;                 }             }               tempBitmap.UnlockBits(gbmData);               return true ;           }//#         public static Bitmap FromGray(byte [,] Gray)         {             int iWidth = Gray.GetLength(1);             int iHeight = Gray.GetLength(0);             Bitmap dstBitmap = ImageProcess.Image.CreateGrayscaleImage(iWidth, iHeight);             BitmapData gbmData = dstBitmap.LockBits(new Rectangle(0, 0, iWidth, iHeight),                       ImageLockMode.ReadWrite, PixelFormat.Format8bppIndexed);             System.IntPtr ScanG = gbmData.Scan0;             int gOffset = gbmData.Stride - iWidth;             unsafe             {                 byte* g = (byte*)(void*)ScanG;                   // 注意这个地方图像的两维方向与数组两维的方向是转置的关系                   for (int i = 0; i < iHeight; i++)                 {                     for (int j = 0; j < iWidth; j++)                     {                           *g=(byte )Gray[i, j] ;                         g++;                     }                     g += gOffset;                 }             }               dstBitmap.UnlockBits(gbmData);               return dstBitmap;         } //# /*********************************补充******************************************/          /// <summary>          /// Create and initialize grayscale image          /// </summary>          public static Bitmap CreateGrayscaleImage( int width, int height )          {               // create new image               Bitmap bmp = new Bitmap( width, height, PixelFormat.Format8bppIndexed );               // set palette to grayscale               SetGrayscalePalette( bmp );               // return new image               return bmp;          }//#            /// <summary>          /// Set pallete of the image to grayscale          /// </summary>          public static void SetGrayscalePalette( Bitmap srcImg )          {               // check pixel format               if ( srcImg.PixelFormat != PixelFormat.Format8bppIndexed )                    throw new ArgumentException( );                 // get palette               ColorPalette cp = srcImg.Palette;               // init palette               for ( int i = 0; i < 256; i++ )               {                    cp.Entries[i] = Color.FromArgb( i, i, i );               }               // set palette back               srcImg.Palette = cp;          }//# /*********************************END********************************************/

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