C# 指针操作图像 细化处理

        /// <summary>
        /// 图形细化
        /// </summary>
        /// <param name="srcImg"></param>
        /// <returns></returns>
        public unsafe Bitmap ToThinner(Bitmap srcImg)
        {
            int iw = srcImg.Width;
            int ih = srcImg.Height;
            bool bModified;     //二值图像修改标志            
            bool bCondition1;   //细化条件1标志            
            bool bCondition2;   //细化条件2标志            
            bool bCondition3;   //细化条件3标志            
            bool bCondition4;   //细化条件4标志
            int nCount;
            //5X5像素块            
            byte[,] neighbour = new byte[5, 5];
            //新建临时存储图像            
            Bitmap NImg = new Bitmap(iw, ih, srcImg.PixelFormat);
            bModified = true;
            //细化修改标志, 用作循环条件
            BitmapData dstData = srcImg.LockBits(new Rectangle(0, 0, iw, ih), ImageLockMode.ReadWrite, srcImg.PixelFormat);
            byte* data = (byte*)(dstData.Scan0);
            //将图像转换为0,1二值得图像; 
            int step = dstData.Stride;
            for (int i = 0; i < dstData.Height; i++)
            {
                for (int j = 0; j < dstData.Width * 3; j += 3)
                {
                    if (data[i * step + j] > 128)
                        //如果是白线条，只要将0改成1，将1改成0
                        data[i * step + j]
                            = data[i * step + j + 1]
                            = data[i * step + j + 2]
                            = 0;
                    else
                        data[i * step + j]
                            = data[i * step + j + 1]
                            = data[i * step + j + 2]
                            = 1;
                }
            }

            BitmapData dstData1 = NImg.LockBits(new Rectangle(0, 0, iw, ih), ImageLockMode.ReadWrite, NImg.PixelFormat);
            byte* data1 = (byte*)(dstData1.Scan0);
            int step1 = dstData1.Stride;
            //细化循环开始           
            while (bModified)
            {
                bModified = false;
                //初始化临时二值图像NImg                
                for (int i = 0; i < dstData1.Height; i++)
                {
                    for (int j = 0; j < dstData1.Width * 3; j++)
                    {
                        data1[i * step1 + j] = 0;
                    }
                }
                for (int i = 2; i < ih - 2; i++)
                {
                    for (int j = 6; j < iw * 3 - 6; j += 3)
                    {
                        bCondition1 = false;
                        bCondition2 = false;
                        bCondition3 = false;
                        bCondition4 = false;
                        if (data[i * step + j] == 0)
                            //若图像的当前点为白色，则跳过                           
                            continue;
                        for (int k = 0; k < 5; k++)
                        {
                            //取以当前点为中心的5X5块                           
                            for (int l = 0; l < 5; l++)
                            {
                                //1代表黑色, 0代表白色                             
                                //neighbour[k, l] = bw[i + k - 2, j + l - 2];         
                                //neighbour[k, l] = data[(i + k - 2) * step + (j + l - 2)];
                                neighbour[k, l] = data[(i + k - 2) * step + (j + l * 3 - 6)];
                            }
                        }
                        //(1)判断条件2<=n(p)<=6          
                        nCount = neighbour[1, 1] + neighbour[1, 2] + neighbour[1, 3] + neighbour[2, 1] + neighbour[2, 3] + neighbour[3, 1] + neighbour[3, 2] + neighbour[3, 3];
                        if (nCount >= 2 && nCount <= 6)
                            bCondition1 = true;
                        else
                        {
                            data1[i * step1 + j] = 1;
                            continue;
                            //跳过, 加快速度                       
                        }
                        //(2)判断s(p)=1                      
                        nCount = 0;
                        if (neighbour[2, 3] == 0 && neighbour[1, 3] == 1)
                            nCount++;
                        if (neighbour[1, 3] == 0 && neighbour[1, 2] == 1)
                            nCount++;
                        if (neighbour[1, 2] == 0 && neighbour[1, 1] == 1)
                            nCount++;
                        if (neighbour[1, 1] == 0 && neighbour[2, 1] == 1)
                            nCount++;
                        if (neighbour[2, 1] == 0 && neighbour[3, 1] == 1)
                            nCount++;
                        if (neighbour[3, 1] == 0 && neighbour[3, 2] == 1)
                            nCount++;
                        if (neighbour[3, 2] == 0 && neighbour[3, 3] == 1)
                            nCount++;
                        if (neighbour[3, 3] == 0 && neighbour[2, 3] == 1)
                            nCount++;
                        if (nCount == 1)
                            bCondition2 = true;
                        else
                        {
                            data1[i * step1 + j] = 1;
                            continue;
                        }
                        //(3)判断p0*p2*p4=0 or s(p2)!=1   
                        if (neighbour[2, 3] * neighbour[1, 2] * neighbour[2, 1] == 0)
                            bCondition3 = true;
                        else
                        {
                            nCount = 0;
                            if (neighbour[0, 2] == 0 && neighbour[0, 1] == 1)
                                nCount++;
                            if (neighbour[0, 1] == 0 && neighbour[1, 1] == 1)
                                nCount++;
                            if (neighbour[1, 1] == 0 && neighbour[2, 1] == 1)
                                nCount++;
                            if (neighbour[2, 1] == 0 && neighbour[2, 2] == 1)
                                nCount++;
                            if (neighbour[2, 2] == 0 && neighbour[2, 3] == 1)
                                nCount++;
                            if (neighbour[2, 3] == 0 && neighbour[1, 3] == 1)
                                nCount++;
                            if (neighbour[1, 3] == 0 && neighbour[0, 3] == 1)
                                nCount++;
                            if (neighbour[0, 3] == 0 && neighbour[0, 2] == 1)
                                nCount++;
                            if (nCount != 1)
                                //s(p2)!=1                              
                                bCondition3 = true;
                            else
                            {
                                data1[i * step1 + j] = 1;
                                continue;
                            }
                        }
                        //(4)判断p2*p4*p6=0 or s(p4)!=1    
                        if (neighbour[1, 2] * neighbour[2, 1] * neighbour[3, 2] == 0)
                            bCondition4 = true;
                        else
                        {
                            nCount = 0;
                            if (neighbour[1, 1] == 0 && neighbour[1, 0] == 1)
                                nCount++;
                            if (neighbour[1, 0] == 0 && neighbour[2, 0] == 1)
                                nCount++;
                            if (neighbour[2, 0] == 0 && neighbour[3, 0] == 1)
                                nCount++;
                            if (neighbour[3, 0] == 0 && neighbour[3, 1] == 1)
                                nCount++;
                            if (neighbour[3, 1] == 0 && neighbour[3, 2] == 1)
                                nCount++;
                            if (neighbour[3, 2] == 0 && neighbour[2, 2] == 1)
                                nCount++;
                            if (neighbour[2, 2] == 0 && neighbour[1, 2] == 1)
                                nCount++;
                            if (neighbour[1, 2] == 0 && neighbour[1, 1] == 1)
                                nCount++;
                            if (nCount != 1)//s(p4)!=1       
                                bCondition4 = true;
                        }
                        if (bCondition1 && bCondition2 && bCondition3 && bCondition4)
                        {
                            data1[i * step1 + j] = 0;
                            bModified = true;
                        }
                        else
                        {
                            data1[i * step1 + j] = 1;
                        }
                    }
                }
                // 将细化了的临时图像bw_tem[w,h]copy到bw[w,h],完成一次细化   
                for (int i = 2; i < ih - 2; i++)
                    for (int j = 2; j < iw * 3 - 2; j++)
                        data[i * step + j] = data1[i * step1 + j];
            }
            for (int i = 2; i < ih - 2; i++)
            {
                for (int j = 6; j < iw * 3 - 6; j += 3)
                {
                    if (data[i * step + j] == 1)

                        data[i * step + j]
                            = data[i * step + j + 1]
                            = data[i * step + j + 2]
                            = 0;

                    else

                        data[i * step + j]
                            = data[i * step + j + 1]
                            = data[i * step + j + 2]
                            = 255;

                }
            }
            srcImg.UnlockBits(dstData);
            NImg.UnlockBits(dstData1);
            return (srcImg);
        }