验证码识别技术研究（1）

            string imgpName = @"005";
            Image image = Image.FromFile(@"G:\" + imgpName + @".jpg");
            Image img = (Image)image.Clone();
            Bitmap bmp = new Bitmap((Image)image.Clone());
            int gray = 0;
            Graphics g = Graphics.FromImage(image);
            int sum = 0;
            int[] zf = new int[256];//灰度数组

            #region 灰度平均值
            for (int x = 0; x < bmp.Width; x++)
            {
                for (int y = 0; y < bmp.Height; y++)
                {
                    //灰度算法
                    gray = (bmp.GetPixel(x, y).R * 299 + bmp.GetPixel(x, y).G * 587 + bmp.GetPixel(x, y).B * 114 + 500) / 1000;
                    zf[gray]++;
                    sum += gray;
                }
            }
            int avg = sum / (bmp.Width * bmp.Height);
            #endregion

            #region 以获得的灰度平均值为阀值，对图像进行二值化处理
            for (int x = 0; x < bmp.Width; x++)
            {
                for (int y = 0; y < bmp.Height; y++)
                {
                    gray = (bmp.GetPixel(x, y).R * 299 + bmp.GetPixel(x, y).G * 587 + bmp.GetPixel(x, y).B * 114 + 500) / 1000;
                    zf[gray]++;
                    sum += gray;
                    Color color = new Color();
                    if (gray > avg)
                    {
                        color = Color.FromArgb(255, 255, 255);
                    }
                    else
                    {
                        color = Color.FromArgb(0, 0, 0);
                    }
                    g.DrawLine(new Pen(color, 1), x, y, x + 1, y + 1);
                }
            }
            #endregion

            #region 直方图绘制
            Graphics gg = Graphics.FromImage(img);
            //string k = ((int)(bmp.Height * 0.5) / zf.Max()).ToString();
            for (int i = 0; i < zf.Length; i++)
            {
                Pen p = new Pen(Color.Red, 1);
                gg.DrawLine(p, i, 0, i, zf[i]);
            }
            #endregion

            img.Save(@"G:\" + imgpName + @"直方图.jpg");
            gg.Dispose();
            image.Save(@"G:\" + imgpName + @"二值化图.jpg");
            image.Dispose();
            g.Dispose();
            MessageBox.Show("OK!\nGray_AVG:" + avg);//灰度平均值

 灰度算法公式：

G = (R * 299 + G * 587 + B * 114 + 500) / 1000