ASP.NET登录验证码解决方案

柔光的暖阳◎ 2021-11-27 02:36 283阅读 0赞

### 文章目录 ###

*   *  \#验证码效果图
     *  \#代码
     *   *  0、html代码
         *  1、Handler中调用验证码生成类
         *  2、验证码图片绘制生成类
         *  3、高斯模糊算法类
     *  \#参考
     *  \#注意

--------------------

在web项目中，为了防止登录被暴力破解，需要在登录的时候加入验证码验证，思路是：  
1）登录页面打开，向 服务端请求生成验证码图片，并将验证码字符串存入session；  
2）登录时将客户端输入的验证码字符串传到服务端，与session中的验证码进行比较，如果验证码正确，再进行登录验证；

--------------------

## \#验证码效果图 ##

![在这里插入图片描述][2019072316011554.png]![在这里插入图片描述][20190723213211325.png]

## \#代码 ##

### 0、html代码 ###

### 1、Handler中调用验证码生成类 ###

public void ProcessRequest (HttpContext context) 
    { 
    	context.Response.ContentType = "image/jpeg";
    	
        Resource.Utility.DrawCaptchaHelper objDrawValidationCode = new Resource.Utility.DrawCaptchaHelper();
        objDrawValidationCode.CaptchaLength = 4;//验证码字符个数
        objDrawValidationCode.IsPixel = true;//随机噪点
    
        objDrawValidationCode.RandomStringCount = 2; //干扰字符个数
        objDrawValidationCode.RandomStringFontSize = 30;//干扰字符字体大小
    
        objDrawValidationCode.FontMinSize = 35;//验证码字体的大小的最小值
        objDrawValidationCode.FontMaxSize = 40;  //验证码字体的大小的最大值
    
        //objDrawValidationCode.GaussianDeviation = 3; //默认0，不使用高斯模糊算法处理图像。
        //objDrawValidationCode.BrightnessValue = 5; //明暗度，默认0，是使用明暗度算法处理图像
    
        objDrawValidationCode.LineCount = 1;  //默认3条。
        objDrawValidationCode.BezierCount = 2;//默认3条。
        
        //边框样式
        //objDrawValidationCode.Border = DrawCaptchaHelper.BorderStyle.RoundRectangle;
    
        using (MemoryStream ms = new MemoryStream())
        { 
            objDrawValidationCode.CreateImage(ms);
            context.Session["ValidateCode"] = objDrawValidationCode.CaptchaStr;//将验证码字符串存入session，用于登录验证
            //return File(ms.GetBuffer(), "image/jpeg");
            context.Response.BinaryWrite(ms.GetBuffer());
        }
    }

### 2、验证码图片绘制生成类 ###

#region 验证码生成类
        /// <summary>
        /// 验证码生成类
        /// </summary>
        public class DrawCaptchaHelper
        { 
            #region 定义和初始化配置字段
            //用户存取验证码字符串
            private string captchaStr = String.Empty;
            /// <summary>
            /// 获取系统生成的随机验证码
            /// </summary>
            public String CaptchaStr
            { 
                get {  return captchaStr; }
            }
            private Int32 captchaLength = 4;
            /// <summary>
            /// 获取和设置验证码字符串的长度
            /// </summary>
            public Int32 CaptchaLength
            { 
                get {  return captchaLength; }
                set {  captchaLength = value; }
            }
            Graphics dc = null;
            private int bgWidth = 130;
            /// <summary>
            /// 验证码的宽度，默认为130
            /// </summary>
            public Int32 Width
            { 
                get {  return bgWidth; }
                set {  bgWidth = value; }
            }
    
            private int bgHeight = 40;
            /// <summary>
            /// 验证码的高度，默认为40
            /// </summary>
            public Int32 Height
            { 
                get {  return bgHeight; }
                set {  bgHeight = value; }
            }
    
            private int fontMinSize = 15;
            /// <summary>
            /// 验证码字体的最小值，默认为15,建议不小于15像素
            /// </summary>
            public Int32 FontMinSize
            { 
                get {  return fontMinSize; }
                set {  fontMinSize = value; }
            }
            private Int32 fontMaxSize = 20;
            /// <summary>
            /// 验证码字体的最大值，默认为20
            /// </summary>
            public Int32 FontMaxSize
            { 
                get {  return fontMaxSize; }
                set {  fontMaxSize = value; }
            }
            private Color[] fontColor = {  };
            /// <summary>
            /// 验证码字体的颜色，默认为系统自动生成字体颜色
            /// </summary>
            public Color[] FontColor
            { 
                get {  return fontColor; }
                set {  fontColor = value; }
            }
            private Color backColor = Color.FromArgb(243, 255, 255);
            /// <summary>
            /// 验证码的背景色，默认为Color.FromArgb(243, 251, 254)
            /// </summary>
            public Color BackgroundColor
            { 
                get {  return backColor; }
                set {  backColor = value; }
            }
            private Int32 bezierCount = 3;
            /// <summary>
            /// 贝塞尔曲线的条数,默认为3条
            /// </summary>
            public Int32 BezierCount
            { 
                get {  return bezierCount; }
                set {  bezierCount = value; }
            }
            private Int32 lineCount = 3;
            /// <summary>
            /// 直线条数，默认为3条
            /// </summary>
            public Int32 LineCount
            { 
                get {  return lineCount; }
                set {  lineCount = value; }
            }
            Random random;
    
            //定义验证码字符及出现频次 ,避免出现 0 o j i l 1 x; 
            private String charCollection = "2,3,4,5,6,7,8,9,a,s,d,f,g,h,z,c,v,b,n,m,k,q,w,e,r,t,y,u,p,A,S,D,F,G,H,Z,C,V,B,N,M,K,Q,W,E,R,T,Y,U,P"; 
            /// <summary>
            /// 随机字符串列表，请使用英文状态下的逗号分隔。
            /// </summary>
            public String CharCollection
            { 
                get {  return charCollection; }
                set {  charCollection = value; }
            }
            private Int32 intCount = 4;
            /// <summary>
            /// 验证码字符串个数，默认为4个字符
            /// </summary>
            public Int32 IntCount
            { 
                get {  return intCount; }
                set {  intCount = value; }
            }
            private Boolean isPixel = true;
            /// <summary>
            /// 是否添加噪点，默认添加，噪点颜色为系统随机生成。
            /// </summary>
            public Boolean IsPixel
            { 
                get {  return isPixel; }
                set {  isPixel = value; }
            }
            /// <summary>
            /// 随机背景字符串的个数
            /// </summary>
            public Int32 RandomStringCount {  get; set; }
            private Int32 randomStringFontSize = 10;
            /// <summary>
            /// 随机背景字符串的大小
            /// </summary>
            public Int32 RandomStringFontSize
            { 
                get {  return randomStringFontSize; }
                set {  randomStringFontSize = value; }
            }
            /// <summary>
            /// 边框样式
            /// </summary>
            public enum BorderStyle
            { 
                /// <summary>
                /// 无边框
                /// </summary>
                None,
                /// <summary>
                /// 矩形边框
                /// </summary>
                Rectangle,
                /// <summary>
                /// 圆角边框
                /// </summary>
                RoundRectangle
            }
            /// <summary>
            /// 设置或获取边框样式
            /// </summary>
            public BorderStyle Border {  get; set; }
    
            private Int32 rotationAngle = 40;
            /// <summary>
            /// 验证码字符串随机转动的角度的最大值
            /// </summary>
            public Int32 RotationAngle
            { 
                get {  return rotationAngle; }
                set {  rotationAngle = value; }
            }
    
            private Point[] strPoint = null;
    
            private Double gaussianDeviation = 0;
            /// <summary>
            /// 对验证码图片进行高斯模糊的阀值，如果设置为0，则不对图片进行高斯模糊，该设置可能会对图片处理的性能有较大影响
            /// </summary>
            public Double GaussianDeviation
            { 
                get {  return gaussianDeviation; }
                set {  gaussianDeviation = value; }
            }
            private Int32 brightnessValue = 0;
            /// <summary>
            /// 对图片进行暗度和亮度的调整，如果该值为0，则不调整。该设置会对图片处理性能有较大影响
            /// </summary>
            public Int32 BrightnessValue
            { 
                get {  return brightnessValue; }
                set {  brightnessValue = value; }
            }
            #endregion
    
            #region wq 新增 边框补(默认1像素)
            int padding = 2;
            public int Padding
            { 
                get {  return padding; }
                set {  padding = value; }
            }
            #endregion
    
            /// <summary>
            /// 构造函数，用于初始化常用变量
            /// </summary>
            public DrawCaptchaHelper()
            { 
                random = new Random(Guid.NewGuid().GetHashCode());
                strPoint = new Point[captchaLength + 1];
                if (gaussianDeviation < 0) gaussianDeviation = 0;
            }
    
            /// <summary>
            /// 生成验证码
            /// </summary>
            /// <param name="target">用于存储图片的一般字节序列</param>
            public MemoryStream CreateImage(MemoryStream target)
            { 
                //新增 wq ,否则后面报错
                if (strPoint.Length != captchaLength)
                { 
                    strPoint = new Point[captchaLength + 1];//wq 新增，原因是：构造函数默认初始化5个元素，假如new后，又改了validationCodeCount的数值，则该数字需要重新初始化
                }
    
                //新增 wq ，否则图片的画布太小
                if (fontMaxSize >= (bgHeight / 5) * 4)
                { 
                    //throw new ArgumentException("字体最大值参数FontMaxSize与验证码高度相近，这会导致描绘验证码字符串时出错，请重新设置参数！");
                    AdjustBitmapSize();
                }
    
                Bitmap bit = new Bitmap(bgWidth + 1, bgHeight + 1);
                //写字符串
                dc = Graphics.FromImage(bit);
                dc.SmoothingMode = SmoothingMode.HighQuality;
                dc.TextRenderingHint = TextRenderingHint.ClearTypeGridFit; ;
                dc.InterpolationMode = InterpolationMode.HighQualityBilinear;
                dc.CompositingQuality = CompositingQuality.HighQuality;
    
                dc.Clear(Color.White);
                //画验证码背景，例如，增加早点，添加曲线和直线等
                dc.DrawImageUnscaled(DrawBackground(), 0, 0);
    
                //绘制验证码
                Bitmap validatecodeImg = DrawRandomString();
                //对随机码图像上的文字进行波形扭曲（扭曲文字方式1）
                validatecodeImg = TwistImage(validatecodeImg, true, 3, 4);
                dc.DrawImageUnscaled(validatecodeImg, 0, 0);
    
                //水波纹效果 文字进行波形扭曲 （扭曲文字方式2）
                //bit = AdjustRippleEffect(bit, 5);
    
                //对图片进行高斯模糊
                if (gaussianDeviation > 0)
                { 
                    GaussianHelper gau = new GaussianHelper();
                    bit = gau.FilterProcessImage(gaussianDeviation, bit);
                }
                //进行暗度和亮度处理
                if (brightnessValue != 0)
                { 
                    //对图片进行调暗处理
                    bit = AdjustBrightness(bit, brightnessValue);
                }
                bit.Save(target, ImageFormat.Gif);
                //brush.Dispose();
                bit.Dispose();
                dc.Dispose();
                return target;
            }
    
            #region 画验证码背景，例如，增加早点，添加曲线和直线等
            /// <summary>
            /// 画验证码背景，例如，增加早点，添加曲线和直线等
            /// </summary>
            /// <returns></returns>
            private Bitmap DrawBackground()
            { 
                Bitmap bit = new Bitmap(bgWidth + 1, bgHeight + 1);
                Graphics g = Graphics.FromImage(bit);
                g.SmoothingMode = SmoothingMode.HighQuality;
    
                g.Clear(Color.White);
                Rectangle rectangle = new Rectangle(0, 0, bgWidth, bgHeight);
                Brush brush = new SolidBrush(backColor);
                g.FillRectangle(brush, rectangle);
    
                //画噪点
                if (isPixel)
                { 
                    g.DrawImageUnscaled(DrawRandomPixel(30), 0, 0);
                }
                //画干扰字符
                g.DrawImageUnscaled(DrawRandBgString(), 0, 0);
    
    
                //画曲线
                g.DrawImageUnscaled(DrawRandomBezier(bezierCount), 0, 0);
                //画直线
                g.DrawImageUnscaled(DrawRandomLine(lineCount), 0, 0);
                //画字符连接线
                //dc.DrawImageUnscaled(DrawStringline(), 0, 0);
                if (Border == BorderStyle.Rectangle)
                { 
                    //绘制边框
                    g.DrawRectangle(new Pen(Color.FromArgb(90, 87, 46)), 0, 0, bgWidth, bgHeight);
                }
                else if (Border == BorderStyle.RoundRectangle)
                { 
                    //画圆角
                    DrawRoundRectangle(g, rectangle, Color.FromArgb(90, 87, 46), 1, 3);
                }
                else
                { 
                    //没有边框
                }
    
                return bit;
    
            }
            #endregion
    
            #region 画正弦曲线
            private Bitmap DrawTwist(Bitmap bmp, Int32 tWidth, Int32 tHeight, float angle, Color color)
            { 
                //为了方便查看效果，在这里我定义了一个常量。
                //它在定义数组的长度和for循环中都要用到。
                int size = bgWidth;
    
                double[] x = new double[size];
                Bitmap b = new Bitmap(bmp.Width, bmp.Height);
                b.MakeTransparent();
                Graphics graphics = Graphics.FromImage(b);
                Pen pen = new Pen(color);
    
                //画正弦曲线的横轴间距参数。建议所用的值应该是 正数且是2的倍数。
                //在这里采用2。
                int val = 2;
    
                float temp = 0.0f;
    
                //把画布下移100。为什么要这样做，只要你把这一句给注释掉，运行一下代码，
                //你就会明白是为什么？
                graphics.TranslateTransform(0, 100);
                graphics.SmoothingMode = SmoothingMode.HighQuality;
                graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;
                for (int i = 0; i < size; i++)
                { 
                    //改变tWidth，实现正弦曲线宽度的变化。
                    //改tHeight，实现正弦曲线高度的变化。
                    x[i] = Math.Sin(2 * Math.PI * i / tWidth) * tHeight;
    
                    graphics.DrawLine(pen, i * val, temp, i * val + val / 2, (float)x[i]);
                    temp = (float)x[i];
                }
                graphics.RotateTransform(60, MatrixOrder.Prepend);
    
                //旋转图片
                // b = KiRotate(b, angle, Color.Transparent);
                return b;
            }
            #endregion
    
            #region 正弦曲线Wave扭曲图片
            /// <summary>
            /// 正弦曲线Wave扭曲图片
            /// </summary>
            /// <param name="srcBmp">图片路径</param>
            /// <param name="bXDir">如果扭曲则选择为True</param>
            /// <param name="dMultValue">波形的幅度倍数，越大扭曲的程度越高，一般为3</param>
            /// <param name="dPhase">波形的起始相位，取值区间[0-2*PI)</param>
            /// <returns></returns>
            public Bitmap TwistImage(Bitmap srcBmp, bool bXDir, double dMultValue, double dPhase)
            { 
                System.Drawing.Bitmap destBmp = new Bitmap(srcBmp.Width, srcBmp.Height);
                double PI2 = 6.283185307179586476925286766559;
                // 将位图背景填充为白色
                System.Drawing.Graphics graph = System.Drawing.Graphics.FromImage(destBmp);
                graph.FillRectangle(new SolidBrush(System.Drawing.Color.White), 0, 0, destBmp.Width, destBmp.Height);
                graph.Dispose();
    
                double dBaseAxisLen = bXDir ? (double)destBmp.Height : (double)destBmp.Width;
    
                for (int i = 0; i < destBmp.Width; i++)
                { 
                    for (int j = 0; j < destBmp.Height; j++)
                    { 
                        double dx = 0;
                        dx = bXDir ? (PI2 * (double)j) / dBaseAxisLen : (PI2 * (double)i) / dBaseAxisLen;
                        dx += dPhase;
                        double dy = Math.Sin(dx);
    
                        // 取得当前点的颜色
                        int nOldX = 0, nOldY = 0;
                        nOldX = bXDir ? i + (int)(dy * dMultValue) : i;
                        nOldY = bXDir ? j : j + (int)(dy * dMultValue);
    
                        System.Drawing.Color color = srcBmp.GetPixel(i, j);
                        if (nOldX >= 0 && nOldX < destBmp.Width
                         && nOldY >= 0 && nOldY < destBmp.Height)
                        { 
                            destBmp.SetPixel(nOldX, nOldY, color);
                        }
                    }
                }
                return destBmp;
            }
            #endregion
    
            #region 图片任意角度旋转
            /// <summary>
            /// 图片任意角度旋转
            /// </summary>
            /// <param name="bmp">原始图Bitmap</param>
            /// <param name="angle">旋转角度</param>
            /// <param name="bkColor">背景色</param>
            /// <returns>输出Bitmap</returns>
            public static Bitmap KiRotate(Bitmap bmp, float angle, Color bkColor)
            { 
                int w = bmp.Width;
                int h = bmp.Height;
    
                PixelFormat pf;
    
                if (bkColor == Color.Transparent)
                { 
                    pf = PixelFormat.Format32bppArgb;
                }
                else
                { 
                    pf = bmp.PixelFormat;
                }
    
                Bitmap tmp = new Bitmap(w, h, pf);
                Graphics g = Graphics.FromImage(tmp);
                g.Clear(bkColor);
                g.DrawImageUnscaled(bmp, 1, 1);
                g.Dispose();
    
                GraphicsPath path = new GraphicsPath();
                path.AddRectangle(new RectangleF(0f, 0f, w, h));
                Matrix mtrx = new Matrix();
                mtrx.Rotate(angle);
                RectangleF rct = path.GetBounds(mtrx);
    
                Bitmap dst = new Bitmap((int)rct.Width, (int)rct.Height, pf);
                g = Graphics.FromImage(dst);
                g.Clear(bkColor);
                g.TranslateTransform(-rct.X, -rct.Y);
                g.RotateTransform(angle);
                g.InterpolationMode = InterpolationMode.HighQualityBilinear;
                g.DrawImageUnscaled(tmp, 0, 0);
                g.Dispose();
                tmp.Dispose();
    
                return dst;
            }
            #endregion
    
            #region 随机生成贝塞尔曲线
            /// <summary>
            /// 随机生成贝塞尔曲线
            /// </summary>
            /// <param name="bmp">一个图片的实例</param>
            /// <param name="lineNum">线条数量</param>
            /// <returns></returns>
            public Bitmap DrawRandomBezier(Int32 lineNum)
            { 
                Bitmap b = new Bitmap(bgWidth, bgHeight);
                b.MakeTransparent();
                Graphics g = Graphics.FromImage(b);
                g.Clear(Color.Transparent);
                g.SmoothingMode = SmoothingMode.HighQuality;
                g.PixelOffsetMode = PixelOffsetMode.HighQuality;
    
                GraphicsPath gPath1 = new GraphicsPath();
                Int32 lineRandNum = random.Next(lineNum);
    
                for (int i = 0; i < (lineNum - lineRandNum); i++)
                { 
                    Pen p = new Pen(GetRandomDeepColor(), 3f);  //wq,增加贝塞尔曲线的线宽参数
                    Point[] point = { 
                                        new Point(random.Next(1, (b.Width / 10)), random.Next(1, (b.Height))),
                                        new Point(random.Next((b.Width / 10) * 2, (b.Width / 10) * 4), random.Next(1, (b.Height))),
                                        new Point(random.Next((b.Width / 10) * 4, (b.Width / 10) * 6), random.Next(1, (b.Height))),
                                        new Point(random.Next((b.Width / 10) * 8, b.Width), random.Next(1, (b.Height)))
                                    };
    
                    gPath1.AddBeziers(point);
                    g.DrawPath(p, gPath1);
                    p.Dispose();
                }
    
                for (int i = 0; i < lineRandNum; i++)
                { 
                    Pen p = new Pen(GetRandomDeepColor());
                    Point[] point = { 
                                new Point(random.Next(1, b.Width), random.Next(1, b.Height)),
                                new Point(random.Next((b.Width / 10) * 2, b.Width), random.Next(1, b.Height)),
                                new Point(random.Next((b.Width / 10) * 4, b.Width), random.Next(1, b.Height)),
                                new Point(random.Next(1, b.Width), random.Next(1, b.Height))
                                    };
                    gPath1.AddBeziers(point);
                    g.DrawPath(p, gPath1);
                    p.Dispose();
                }
                return b;
            }
            #endregion
    
            #region 画直线
            /// <summary>
            /// 画直线
            /// </summary>
            /// <param name="bmp">一个bmp实例</param>
            /// <param name="lineNum">线条个数</param>
            /// <returns></returns>
            public Bitmap DrawRandomLine(Int32 lineNum)
            { 
                if (lineNum < 0) throw new ArgumentNullException("参数bmp为空！");
                Bitmap b = new Bitmap(bgWidth, bgHeight);
                b.MakeTransparent();
                Graphics g = Graphics.FromImage(b);
                g.Clear(Color.Transparent);
                g.PixelOffsetMode = PixelOffsetMode.HighQuality;
                g.SmoothingMode = SmoothingMode.HighQuality;
                for (int i = 0; i < lineNum; i++)
                { 
                    Pen p = new Pen(GetRandomDeepColor());
                    Point pt1 = new Point(random.Next(1, (b.Width / 5) * 2), random.Next(b.Height));
                    Point pt2 = new Point(random.Next((b.Width / 5) * 3, b.Width), random.Next(b.Height));
                    g.DrawLine(p, pt1, pt2);
                    p.Dispose();
                }
    
                return b;
            }
            #endregion
    
            #region 画随机噪点
            /// <summary>
            /// 画随机噪点
            /// </summary>
            /// <param name="pixNum">噪点的百分比</param>
            /// <returns></returns>
            public Bitmap DrawRandomPixel(Int32 pixNum)
            { 
                Bitmap b = new Bitmap(bgWidth, bgHeight);
                b.MakeTransparent();
                Graphics graph = Graphics.FromImage(b);
                graph.SmoothingMode = SmoothingMode.HighQuality;
                graph.InterpolationMode = InterpolationMode.HighQualityBilinear;
    
                //画噪点
                for (int i = 0; i < (bgHeight * bgWidth) / pixNum; i++)
                { 
                    int x = random.Next(b.Width);
                    int y = random.Next(b.Height);
                    b.SetPixel(x, y, GetRandomDeepColor());
                    //下移坐标重新画点
                    if ((x + 1) < b.Width && (y + 1) < b.Height)
                    { 
                        //画图片的前景噪音点
                        graph.DrawRectangle(new Pen(Color.Silver), random.Next(b.Width), random.Next(b.Height), 1, 1);
                    }
    
                }
    
                return b;
            }
            #endregion
    
            #region 画随机字符串中间连线
            /// <summary>
            /// 画随机字符串中间连线
            /// </summary>
            /// <returns></returns>
            private Bitmap DrawStringline()
            { 
                Bitmap b = new Bitmap(bgWidth, bgHeight);
                b.MakeTransparent();
                Graphics g = Graphics.FromImage(b);
                g.SmoothingMode = SmoothingMode.AntiAlias;
    
                Point[] p = new Point[captchaLength];
                for (int i = 0; i < captchaLength; i++)
                { 
                    p[i] = strPoint[i];
                    //throw new Exception(strPoint.Length.ToString());
                }
                // g.DrawBezier(new Pen(GetRandomDeepColor()), strPoint);
                //g.DrawClosedCurve(new Pen(GetRandomDeepColor()), strPoint);
                g.DrawCurve(new Pen(GetRandomDeepColor(), 1), strPoint);
    
                return b;
            }
            #endregion
    
            #region 写入验证码的字符串
            /// <summary>
            /// 写入验证码的字符串
            /// </summary>
            private Bitmap DrawRandomString()
            { 
                if (fontMaxSize >= (bgHeight / 5) * 4)
                { 
                    //throw new ArgumentException("字体最大值参数FontMaxSize与验证码高度相近，这会导致描绘验证码字符串时出错，请重新设置参数！");
                    AdjustBitmapSize();
                }
    
    
                Bitmap b = new Bitmap(bgWidth, bgHeight);
                b.MakeTransparent();
                Graphics g = Graphics.FromImage(b);
    
                g.Clear(Color.Transparent);
                g.PixelOffsetMode = PixelOffsetMode.Half;
                g.SmoothingMode = SmoothingMode.HighQuality;
                g.TextRenderingHint = TextRenderingHint.SingleBitPerPixelGridFit;
                g.InterpolationMode = InterpolationMode.HighQualityBilinear;
    
                char[] chars = GetRandomString(captchaLength).ToCharArray();//拆散字符串成单字符数组
                captchaStr = new string(chars); //这个类的外部，也可以通过这个参数，获取到本次的验证码字符串值。
    
                //设置字体显示格式
                StringFormat format = new StringFormat(StringFormatFlags.NoClip);
                format.Alignment = StringAlignment.Center;
                format.LineAlignment = StringAlignment.Center;
                FontFamily f = new FontFamily(GenericFontFamilies.Monospace);
    
    
                Int32 charNum = chars.Length;
    
                Point sPoint = new Point();
                Int32 fontSize = 9;
                for (int i = 0; i < captchaLength; i++)
                { 
                    int findex = random.Next(captchaLength + 1);// random.Next(5);
                    //定义字体
                    Font textFont = new Font(f, random.Next(fontMinSize, fontMaxSize), FontStyle.Bold);
                    //定义画刷，用于写字符串
                    //Brush brush = new SolidBrush(GetRandomDeepColor());
                    Int32 textFontSize = Convert.ToInt32(textFont.Size);
                    fontSize = textFontSize;
    
                    var t = (bgWidth / charNum)/2;
                    Point point = new Point(random.Next((bgWidth / charNum) * (i) + t - 2, (bgWidth / charNum) * (i + 1) -t+ 2), random.Next(bgHeight / 5 + textFontSize / 2, bgHeight - textFontSize / 2));
    
    
    
                    //如果当前字符X坐标小于字体的二分之一大小
                    if (point.X < textFontSize / 2)
                    { 
                        point.X = point.X + textFontSize / 2;
                    }
                    //防止文字叠加
                    if (i > 0 && (point.X - sPoint.X < (textFontSize / 2 + textFontSize / 2)))
                    { 
                        point.X = point.X + textFontSize;
                    }
                    //如果当前字符X坐标大于图片宽度，就减去字体的宽度
                    if (point.X > (bgWidth - textFontSize / 2))
                    { 
                        point.X = bgWidth - textFontSize / 2;
                    }
    
                    sPoint = point;
    
                    float angle = random.Next(-rotationAngle, rotationAngle);//转动的度数
                    g.TranslateTransform(point.X, point.Y);//移动光标到指定位置
                    g.RotateTransform(angle);
    
                    //设置渐变画刷 
                    Rectangle myretang = new Rectangle(0, 1, Convert.ToInt32(textFont.Size), Convert.ToInt32(textFont.Size));
                    Color c = GetRandomDeepColor();
                    LinearGradientBrush mybrush2 = new LinearGradientBrush(myretang, c, GetLightColor(c, 120), random.Next(180));
    
                    g.DrawString(chars[i].ToString(), textFont, mybrush2, 1, 1, format);
    
                    g.RotateTransform(-angle);//转回去
                    g.TranslateTransform(-point.X, -point.Y);//移动光标到指定位置，每个字符紧凑显示，避免被软件识别
    
                    strPoint[i] = point;
    
                    textFont.Dispose();
                    mybrush2.Dispose();
                }
                return b;
            }
            #endregion
    
            #region 新增的矫正验证码的宽高
            private void AdjustBitmapSize()
            { 
                int fSize = fontMaxSize;
                int fWidth = fSize + Padding;
    
                int imageWidth = (int)(captchaLength * fWidth) + 4 + Padding * 2;
                int imageHeight = fSize * 2 + Padding;
                bgWidth = imageWidth;
                bgHeight = imageHeight;
            }
            #endregion
    
            #region 画干扰背景文字
            /// <summary>
            /// 画背景干扰文字
            /// </summary>
            /// <returns></returns>
            private Bitmap DrawRandBgString()
            { 
                Bitmap b = new Bitmap(bgWidth, bgHeight);
                String[] randStr = {  "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z" };
                b.MakeTransparent();
                Graphics g = Graphics.FromImage(b);
    
                g.Clear(Color.Transparent);
                g.PixelOffsetMode = PixelOffsetMode.HighQuality;
                g.SmoothingMode = SmoothingMode.HighQuality;
                g.TextRenderingHint = TextRenderingHint.AntiAlias;
                g.InterpolationMode = InterpolationMode.HighQualityBilinear;
    
                //设置字体显示格式
                StringFormat format = new StringFormat(StringFormatFlags.NoClip);
                format.Alignment = StringAlignment.Center;
                format.LineAlignment = StringAlignment.Center;
    
                FontFamily f = new FontFamily(GenericFontFamilies.Serif);
                Font textFont = new Font(f, randomStringFontSize, FontStyle.Underline);
    
                int randAngle = 60; //随机转动角度
    
                for (int i = 0; i < RandomStringCount; i++)
                { 
    
                    Brush brush = new System.Drawing.SolidBrush(GetRandomLightColor());
                    Point pot = new Point(random.Next(randomStringFontSize / 2, bgWidth - randomStringFontSize / 2),
                        random.Next(randomStringFontSize / 2, bgHeight - randomStringFontSize/2));
                    //随机转动的度数
                    float angle = random.Next(-randAngle, randAngle);
    
                    //转动画布
                    g.RotateTransform(angle);
                    g.DrawString(randStr[random.Next(randStr.Length)], textFont, brush, pot, format);
                    //转回去，为下一个字符做准备
                    g.RotateTransform(-angle);
                    //释放资源
                    brush.Dispose();
                }
                textFont.Dispose();
                format.Dispose();
                f.Dispose();
    
                return b;
            }
            #endregion
    
            #region 生成随机字符串
            /// <summary>
            /// 生成随机字符串 
            /// </summary>
            /// <returns></returns>
            private string GetRandomString(Int32 textLength)
            { 
                string[] randomArray = charCollection.Split(','); //将字符串生成数组 
                int arrayLength = randomArray.Length;
                string randomString = "";
                for (int i = 0; i < textLength; i++)
                { 
                    randomString += randomArray[random.Next(0, arrayLength)];
                }
                //Session["CheckCode"] = randomString;
                return randomString; //长度是textLength +1
            }
            #endregion
    
            #region 内部方法：绘制验证码背景
            private void DrawBackground(HatchStyle hatchStyle)
            { 
                //设置填充背景时用的笔刷
                HatchBrush hBrush = new HatchBrush(hatchStyle, backColor);
    
                //填充背景图片
                dc.FillRectangle(hBrush, 0, 0, this.bgWidth, this.bgHeight);
            }
            #endregion
    
            #region 根据指定长度，返回随机验证码
            /// <summary>
            /// 根据指定长度，返回随机验证码
            /// </summary>
            /// <param >制定长度</param>
            /// <returns>随即验证码</returns>
            public string Next(int length)
            { 
                this.captchaStr = GetRandomCode(length);
                return this.captchaStr;
            }
            #endregion
    
            #region 内部方法：返回指定长度的随机验证码字符串
            /// <summary>
            /// 根据指定大小返回随机验证码
            /// </summary>
            /// <param >字符串长度</param>
            /// <returns>随机字符串</returns>
            private string GetRandomCode(int length)
            { 
                StringBuilder sb = new StringBuilder(6);
    
                for (int i = 0; i < length; i++)
                { 
                    sb.Append(Char.ConvertFromUtf32(RandomAZ09()));
                }
    
                return sb.ToString();
            }
            #endregion
    
            #region 内部方法：产生随机数和随机点
    
            /// <summary>
            /// 产生0-9A-Z的随机字符代码
            /// </summary>
            /// <returns>字符代码</returns>
            private int RandomAZ09()
            { 
                int result = 48;
                Random ram = new Random();
                int i = ram.Next(2);
    
                switch (i)
                { 
                    case 0:
                        result = ram.Next(48, 58);
                        break;
                    case 1:
                        result = ram.Next(65, 91);
                        break;
                }
    
                return result;
            }
    
            /// <summary>
            /// 返回一个随机点，该随机点范围在验证码背景大小范围内
            /// </summary>
            /// <returns>Point对象</returns>
            private Point RandomPoint()
            { 
                Random ram = new Random();
                Point point = new Point(ram.Next(this.bgWidth), ram.Next(this.bgHeight));
                return point;
            }
            #endregion
    
            #region 随机生成颜色值
            /// <summary>
            /// 生成随机深颜色
            /// </summary>
            /// <returns></returns>
            public Color GetRandomDeepColor()
            { 
                int nRed, nGreen, nBlue;    // nBlue,nRed nGreen 相差大一点 nGreen 小一些
                //int high = 255; 
                int redLow = 160;
                int greenLow = 100;
                int blueLow = 160;
                nRed = random.Next(redLow);
                nGreen = random.Next(greenLow);
                nBlue = random.Next(blueLow);
                Color color = Color.FromArgb(nRed, nGreen, nBlue);
                return color;
            }
    
            /// <summary>
            /// 生成随机浅颜色
            /// </summary>
            /// <returns>randomColor</returns>
            public Color GetRandomLightColor()
            { 
                int nRed, nGreen, nBlue;    //越大颜色越浅
                int low = 180;           //色彩的下限
                int high = 255;          //色彩的上限 
                nRed = random.Next(high) % (high - low) + low;
                nGreen = random.Next(high) % (high - low) + low;
                nBlue = random.Next(high) % (high - low) + low;
                Color color = Color.FromArgb(nRed, nGreen, nBlue);
                return color;
            }
            /// <summary>
            /// 生成随机颜色值
            /// </summary>
            /// <returns></returns>
            public Color GetRandomColor()
            { 
                int nRed, nGreen, nBlue;    //越大颜色越浅
                int low = 10;           //色彩的下限
                int high = 255;          //色彩的上限 
                nRed = random.Next(high) % (high - low) + low;
                nGreen = random.Next(high) % (high - low) + low;
                nBlue = random.Next(high) % (high - low) + low;
                Color color = Color.FromArgb(nRed, nGreen, nBlue);
                return color;
            }
            /// <summary>
            /// 获取与当前颜色值相加后的颜色
            /// </summary>
            /// <param name="c"></param>
            /// <returns></returns>
            public Color GetLightColor(Color c, Int32 value)
            { 
                int nRed = c.R, nGreen = c.G, nBlue = c.B;    //越大颜色越浅
                if (nRed + value < 255 && nRed + value > 0)
                { 
                    nRed = c.R + 40;
                }
                if (nGreen + value < 255 && nGreen + value > 0)
                { 
                    nGreen = c.G + 40;
                }
                if (nBlue + value < 255 && nBlue + value > 0)
                { 
                    nBlue = c.B + 40;
                }
                Color color = Color.FromArgb(nRed, nGreen, nBlue);
                return color;
            }
            #endregion
    
            #region 合并图片
            /// <summary> 
            /// 合并图片 
            /// </summary> 
            /// <param name="maps"></param> 
            /// <returns></returns> 
            private Bitmap MergerImg(params Bitmap[] maps)
            { 
                int i = maps.Length;
                if (i == 0)
                    throw new Exception("图片数不能够为0");
                //创建要显示的图片对象,根据参数的个数设置宽度 
                Bitmap backgroudImg = new Bitmap(i * 12, 16);
                Graphics g = Graphics.FromImage(backgroudImg);
                //清除画布,背景设置为白色 
                g.Clear(System.Drawing.Color.White);
                for (int j = 0; j < i; j++)
                { 
                    //g.DrawImage(maps[j], j * 11, 0, maps[j].Width, maps[j].Height);
                    g.DrawImageUnscaled(maps[j], 0, 0);
                }
                g.Dispose();
                return backgroudImg;
            }
            #endregion
    
            #region 生成不重复的随机数，该函数会消耗大量系统资源
            /// <summary>
            /// 生成不重复的随机数，该函数会消耗大量系统资源
            /// </summary>
            /// <returns></returns>
            private static int GetRandomSeed()
            { 
                byte[] bytes = new byte[4];
                System.Security.Cryptography.RNGCryptoServiceProvider rng = new System.Security.Cryptography.RNGCryptoServiceProvider();
                rng.GetBytes(bytes);
                return BitConverter.ToInt32(bytes, 0);
            }
            #endregion
    
            #region 缩放图片
            /// <summary>
            /// 缩放图片
            /// </summary>
            /// <param name="bmp">原始Bitmap</param>
            /// <param name="newW">新的宽度</param>
            /// <param name="newH">新的高度</param>
            /// <param name="Mode">缩放质量</param>
            /// <returns>处理以后的图片</returns>
            public static Bitmap KiResizeImage(Bitmap bmp, int newW, int newH, InterpolationMode Mode)
            { 
                try
                { 
                    Bitmap b = new Bitmap(newW, newH);
                    Graphics g = Graphics.FromImage(b);
                    // 插值算法的质量
                    g.InterpolationMode = Mode;
                    g.DrawImage(bmp, new Rectangle(0, 0, newW, newH), new Rectangle(0, 0, bmp.Width, bmp.Height), GraphicsUnit.Pixel);
                    g.Dispose();
                    return b;
                }
                catch
                { 
                    return null;
                }
            }
            #endregion
    
            #region 绘制圆角矩形
            /// <summary>
            /// C# GDI+ 绘制圆角矩形
            /// </summary>
            /// <param name="g">Graphics 对象</param>
            /// <param name="rectangle">Rectangle 对象，圆角矩形区域</param>
            /// <param name="borderColor">边框颜色</param>
            /// <param name="borderWidth">边框宽度</param>
            /// <param name="r">圆角半径</param>
            private static void DrawRoundRectangle(Graphics g, Rectangle rectangle, Color borderColor, float borderWidth, int r)
            { 
                // 如要使边缘平滑，请取消下行的注释
                g.SmoothingMode = SmoothingMode.HighQuality;
    
                // 由于边框也需要一定宽度，需要对矩形进行修正
                //rectangle = new Rectangle(rectangle.X, rectangle.Y, rectangle.Width, rectangle.Height);
                Pen p = new Pen(borderColor, borderWidth);
                // 调用 getRoundRectangle 得到圆角矩形的路径，然后再进行绘制
                g.DrawPath(p, getRoundRectangle(rectangle, r));
            }
            #endregion
    
            #region 根据普通矩形得到圆角矩形的路径
            /// <summary>
            /// 根据普通矩形得到圆角矩形的路径
            /// </summary>
            /// <param name="rectangle">原始矩形</param>
            /// <param name="r">半径</param>
            /// <returns>图形路径</returns>
            private static GraphicsPath getRoundRectangle(Rectangle rectangle, int r)
            { 
                int l = 2 * r;
                // 把圆角矩形分成八段直线、弧的组合，依次加到路径中
                GraphicsPath gp = new GraphicsPath();
                gp.AddLine(new Point(rectangle.X + r, rectangle.Y), new Point(rectangle.Right - r, rectangle.Y));
                gp.AddArc(new Rectangle(rectangle.Right - l, rectangle.Y, l, l), 270F, 90F);
    
                gp.AddLine(new Point(rectangle.Right, rectangle.Y + r), new Point(rectangle.Right, rectangle.Bottom - r));
                gp.AddArc(new Rectangle(rectangle.Right - l, rectangle.Bottom - l, l, l), 0F, 90F);
    
                gp.AddLine(new Point(rectangle.Right - r, rectangle.Bottom), new Point(rectangle.X + r, rectangle.Bottom));
                gp.AddArc(new Rectangle(rectangle.X, rectangle.Bottom - l, l, l), 90F, 90F);
    
                gp.AddLine(new Point(rectangle.X, rectangle.Bottom - r), new Point(rectangle.X, rectangle.Y + r));
                gp.AddArc(new Rectangle(rectangle.X, rectangle.Y, l, l), 180F, 90F);
                return gp;
            }
            #endregion
    
            #region 柔化
            ///<summary>
            /// 柔化
            /// </summary>
            /// <param name="b">原始图</param>
            /// <returns>输出图</returns>
            public static Bitmap KiBlur(Bitmap b)
            { 
    
                if (b == null)
                { 
                    return null;
                }
    
                int w = b.Width;
                int h = b.Height;
    
                try
                { 
    
                    Bitmap bmpRtn = new Bitmap(w, h, PixelFormat.Format24bppRgb);
    
                    BitmapData srcData = b.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);
                    BitmapData dstData = bmpRtn.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.WriteOnly, PixelFormat.Format24bppRgb);
    
                    unsafe
                    { 
                        byte* pIn = (byte*)srcData.Scan0.ToPointer();
                        byte* pOut = (byte*)dstData.Scan0.ToPointer();
                        int stride = srcData.Stride;
                        byte* p;
    
                        for (int y = 0; y < h; y++)
                        { 
                            for (int x = 0; x < w; x++)
                            { 
                                //取周围9点的值
                                if (x == 0 || x == w - 1 || y == 0 || y == h - 1)
                                { 
                                    //不做
                                    pOut[0] = pIn[0];
                                    pOut[1] = pIn[1];
                                    pOut[2] = pIn[2];
                                }
                                else
                                { 
                                    int r1, r2, r3, r4, r5, r6, r7, r8, r9;
                                    int g1, g2, g3, g4, g5, g6, g7, g8, g9;
                                    int b1, b2, b3, b4, b5, b6, b7, b8, b9;
    
                                    float vR, vG, vB;
    
                                    //左上
                                    p = pIn - stride - 3;
                                    r1 = p[2];
                                    g1 = p[1];
                                    b1 = p[0];
    
                                    //正上
                                    p = pIn - stride;
                                    r2 = p[2];
                                    g2 = p[1];
                                    b2 = p[0];
    
                                    //右上
                                    p = pIn - stride + 3;
                                    r3 = p[2];
                                    g3 = p[1];
                                    b3 = p[0];
    
                                    //左侧
                                    p = pIn - 3;
                                    r4 = p[2];
                                    g4 = p[1];
                                    b4 = p[0];
    
                                    //右侧
                                    p = pIn + 3;
                                    r5 = p[2];
                                    g5 = p[1];
                                    b5 = p[0];
    
                                    //右下
                                    p = pIn + stride - 3;
                                    r6 = p[2];
                                    g6 = p[1];
                                    b6 = p[0];
    
                                    //正下
                                    p = pIn + stride;
                                    r7 = p[2];
                                    g7 = p[1];
                                    b7 = p[0];
    
                                    //右下
                                    p = pIn + stride + 3;
                                    r8 = p[2];
                                    g8 = p[1];
                                    b8 = p[0];
    
                                    //自己
                                    p = pIn;
                                    r9 = p[2];
                                    g9 = p[1];
                                    b9 = p[0];
    
                                    vR = (float)(r1 + r2 + r3 + r4 + r5 + r6 + r7 + r8 + r9);
                                    vG = (float)(g1 + g2 + g3 + g4 + g5 + g6 + g7 + g8 + g9);
                                    vB = (float)(b1 + b2 + b3 + b4 + b5 + b6 + b7 + b8 + b9);
    
                                    vR /= 9;
                                    vG /= 9;
                                    vB /= 9;
    
                                    pOut[0] = (byte)vB;
                                    pOut[1] = (byte)vG;
                                    pOut[2] = (byte)vR;
    
                                }
    
                                pIn += 3;
                                pOut += 3;
                            }// end of x
    
                            pIn += srcData.Stride - w * 3;
                            pOut += srcData.Stride - w * 3;
                        } // end of y
                    }
    
                    b.UnlockBits(srcData);
                    bmpRtn.UnlockBits(dstData);
    
                    return bmpRtn;
                }
                catch
                { 
                    return null;
                }
    
            } // end of KiBlur
            #endregion
    
            #region 滤镜
            /// <summary>
            /// 红色滤镜
            /// </summary>
            /// <param name="bitmap">Bitmap</param>
            /// <param name="threshold">阀值 -255~255</param>
            /// <returns></returns>
            public System.Drawing.Bitmap AdjustToRed(System.Drawing.Bitmap bitmap, int threshold)
            { 
                for (int y = 0; y < bitmap.Height; y++)
                { 
                    for (int x = 0; x < bitmap.Width; x++)
                    { 
                        // 取得每一個 pixel
                        var pixel = bitmap.GetPixel(x, y);
                        var pR = pixel.R + threshold;
                        pR = Math.Max(pR, 0);
                        pR = Math.Min(255, pR);
                        // 將改過的 RGB 寫回
                        // 只寫入紅色的值 , G B 都放零
                        System.Drawing.Color newColor = System.Drawing.Color.FromArgb(pixel.A, pR, 0, 0);
                        bitmap.SetPixel(x, y, newColor);
                    }
                }
                // 回傳結果
                return bitmap;
            }
    
            /// <summary>
            /// 绿色滤镜
            /// </summary>
            /// <param name="bitmap">一个图片实例</param>
            /// <param name="threshold">阀值 -255~+255</param>
            /// <returns></returns>
            public System.Drawing.Bitmap AdjustToGreen(System.Drawing.Bitmap bitmap, int threshold)
            { 
                for (int y = 0; y < bitmap.Height; y++)
                { 
                    for (int x = 0; x < bitmap.Width; x++)
                    { 
                        // 取得每一個 pixel
                        var pixel = bitmap.GetPixel(x, y);
                        //判斷是否超過255 如果超過就是255
                        var pG = pixel.G + threshold;
                        //如果小於0就為0
                        if (pG > 255) pG = 255;
                        if (pG < 0) pG = 0;
                        // 將改過的 RGB 寫回
                        // 只寫入綠色的值 , R B 都放零
                        System.Drawing.Color newColor = System.Drawing.Color.FromArgb(pixel.A, 0, pG, 0);
                        bitmap.SetPixel(x, y, newColor);
                    }
                }
                // 回傳結果
                return bitmap;
            }
            /// <summary>
            /// 蓝色滤镜
            /// </summary>
            /// <param name="bitmap">一个图片实例</param>
            /// <param name="threshold">阀值 -255~255</param>
            /// <returns></returns>
            public System.Drawing.Bitmap AdjustToBlue(System.Drawing.Bitmap bitmap, int threshold)
            { 
                for (int y = 0; y < bitmap.Height; y++)
                { 
                    for (int x = 0; x < bitmap.Width; x++)
                    { 
                        // 取得每一個 pixel
                        var pixel = bitmap.GetPixel(x, y);
                        //判斷是否超過255 如果超過就是255
                        var pB = pixel.B + threshold;
                        //如果小於0就為0
                        if (pB > 255) pB = 255;
                        if (pB < 0) pB = 0;
                        // 將改過的 RGB 寫回
                        // 只寫入藍色的值 , R G 都放零
                        System.Drawing.Color newColor = System.Drawing.Color.FromArgb(pixel.A, 0, 0, pB);
                        bitmap.SetPixel(x, y, newColor);
                    }
                }
                // 回傳結果
                return bitmap;
            }
            /// <summary>
            /// 调整 RGB 色调
            /// </summary>
            /// <param name="bitmap"></param>
            /// <param name="thresholdRed">红色阀值</param>
            /// <param name="thresholdBlue">蓝色阀值</param>
            /// <param name="thresholdGreen">绿色阀值</param>
            /// <returns></returns>
            public System.Drawing.Bitmap AdjustToCustomColor(System.Drawing.Bitmap bitmap, int thresholdRed, int thresholdGreen, int thresholdBlue)
            { 
                for (int y = 0; y < bitmap.Height; y++)
                { 
                    for (int x = 0; x < bitmap.Width; x++)
                    { 
                        // 取得每一個 pixel
                        var pixel = bitmap.GetPixel(x, y);
                        //判斷是否超過255 如果超過就是255
                        var pG = pixel.G + thresholdGreen;
                        //如果小於0就為0
                        if (pG > 255) pG = 255;
                        if (pG < 0) pG = 0;
                        //判斷是否超過255 如果超過就是255
                        var pR = pixel.R + thresholdRed;
                        //如果小於0就為0
                        if (pR > 255) pR = 255;
                        if (pR < 0) pR = 0;
                        //判斷是否超過255 如果超過就是255
                        var pB = pixel.B + thresholdBlue;
                        //如果小於0就為0
                        if (pB > 255) pB = 255;
                        if (pB < 0) pB = 0;
                        // 將改過的 RGB 寫回
                        // 只寫入綠色的值 , R B 都放零
                        System.Drawing.Color newColor = System.Drawing.Color.FromArgb(pixel.A, pR, pG, pB);
                        bitmap.SetPixel(x, y, newColor);
                    }
                }
                return bitmap;
            }
            #endregion
    
            #region 图片去色（图片黑白化）
            /// <summary>
            /// 图片去色（图片黑白化）
            /// </summary>
            /// <param name="original">一个需要处理的图片</param>
            /// <returns></returns>
            public static Bitmap MakeGrayscale(Bitmap original)
            { 
                //create a blank bitmap the same size as original
                Bitmap newBitmap = new Bitmap(original.Width, original.Height);
    
                //get a graphics object from the new image
                Graphics g = Graphics.FromImage(newBitmap);
                g.SmoothingMode = SmoothingMode.HighQuality;
                //create the grayscale ColorMatrix
                ColorMatrix colorMatrix = new ColorMatrix(new float[][]
                              { 
                                 new float[] { .3f, .3f, .3f, 0, 0},
                                 new float[] { .59f, .59f, .59f, 0, 0},
                                 new float[] { .11f, .11f, .11f, 0, 0},
                                 new float[] { 0, 0, 0, 1, 0},
                                 new float[] { 0, 0, 0, 0, 1}
                              });
    
                //create some image attributes
                ImageAttributes attributes = new ImageAttributes();
    
                //set the color matrix attribute
                attributes.SetColorMatrix(colorMatrix);
    
                //draw the original image on the new image
                //using the grayscale color matrix
                g.DrawImage(original, new Rectangle(0, 0, original.Width, original.Height),
                   0, 0, original.Width, original.Height, GraphicsUnit.Pixel, attributes);
    
                //dispose the Graphics object
                g.Dispose();
                return newBitmap;
            }
            #endregion
    
            #region 增加或減少亮度
            /// <summary>
            /// 增加或減少亮度
            /// </summary>
            /// <param name="img">System.Drawing.Image Source </param>
            /// <param name="valBrightness">0~255</param>
            /// <returns></returns>
            public System.Drawing.Bitmap AdjustBrightness(System.Drawing.Image img, int valBrightness)
            { 
                // 讀入欲轉換的圖片並轉成為 Bitmap
                System.Drawing.Bitmap bitmap = new System.Drawing.Bitmap(img);
    
                for (int y = 0; y < bitmap.Height; y++)
                { 
                    for (int x = 0; x < bitmap.Width; x++)
                    { 
                        // 取得每一個 pixel
                        var pixel = bitmap.GetPixel(x, y);
    
                        // 判斷 如果處理過後 255 就設定為 255 如果小於則設定為 0
                        var pR = ((pixel.R + valBrightness > 255) ? 255 : pixel.R + valBrightness) < 0 ? 0 : ((pixel.R + valBrightness > 255) ? 255 : pixel.R + valBrightness);
                        var pG = ((pixel.G + valBrightness > 255) ? 255 : pixel.G + valBrightness) < 0 ? 0 : ((pixel.G + valBrightness > 255) ? 255 : pixel.G + valBrightness);
                        var pB = ((pixel.B + valBrightness > 255) ? 255 : pixel.B + valBrightness) < 0 ? 0 : ((pixel.B + valBrightness > 255) ? 255 : pixel.B + valBrightness);
    
                        // 將改過的 RGB 寫回
                        System.Drawing.Color newColor = System.Drawing.Color.FromArgb(pixel.A, pR, pG, pB);
    
                        bitmap.SetPixel(x, y, newColor);
    
                    }
                }
                // 回傳結果
                return bitmap;
            }
            #endregion
    
            #region 浮雕效果
            /// <summary>
            /// 浮雕效果
            /// </summary>
            /// <param name="src">一个图片实例</param>
            /// <returns></returns>
            public Bitmap AdjustToStone(Bitmap src)
            { 
                // 依照 Format24bppRgb 每三个表示一 Pixel 0: 蓝 1: 绿 2: 红
                BitmapData bitmapData = src.LockBits(new Rectangle(0, 0, src.Width, src.Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
    
                unsafe
                { 
                    // 抓住第一个 Pixel 第一个数值
                    byte* p = (byte*)(void*)bitmapData.Scan0;
    
                    // 跨步值 - 宽度 *3 可以算出畸零地 之后跳到下一行
                    int nOffset = bitmapData.Stride - src.Width * 3;
    
                    for (int y = 0; y < src.Height; ++y)
                    { 
                        for (int x = 0; x < src.Width; ++x)
                        { 
                            // 为了理解方便 所以特地在命名
                            int r, g, b;
                            // 先取得下一个 Pixel
                            var q = p + 3;
                            r = Math.Abs(p[2] - q[2] + 128);
                            r = r < 0 ? 0 : r;
                            r = r > 255 ? 255 : r;
                            p[2] = (byte)r;
    
                            g = Math.Abs(p[1] - q[1] + 128);
                            g = g < 0 ? 0 : g;
                            g = g > 255 ? 255 : g;
                            p[1] = (byte)g;
    
                            b = Math.Abs(p[0] - q[0] + 128);
                            b = b < 0 ? 0 : b;
                            b = b > 255 ? 255 : b;
                            p[0] = (byte)b;
    
                            // 跳去下一个 Pixel
                            p += 3;
    
                        }
                        // 跨越畸零地
                        p += nOffset;
                    }
                }
                src.UnlockBits(bitmapData);
                return src;
            }
            #endregion
    
            #region 水波纹效果
            /// <summary>
            /// 水波纹效果
            /// </summary>
            /// <param name="src"></param>
            /// <param name="nWave">坡度</param>
            /// www.it165.net
            /// <returns></returns>
            public Bitmap AdjustRippleEffect(Bitmap src, short nWave)
            { 
    
                int nWidth = src.Width;
                int nHeight = src.Height;
    
                // 透过公式进行水波纹的採样
    
                PointF[,] fp = new PointF[nWidth, nHeight];
    
                Point[,] pt = new Point[nWidth, nHeight];
    
                Point mid = new Point();
                mid.X = nWidth / 2;
                mid.Y = nHeight / 2;
    
                double newX, newY;
                double xo, yo;
    
                //先取样将水波纹座标跟RGB取出
                for (int x = 0; x < nWidth; ++x)
                    for (int y = 0; y < nHeight; ++y)
                    { 
                        xo = ((double)nWave * Math.Sin(2.0 * 3.1415 * (float)y / 128.0));
                        yo = ((double)nWave * Math.Cos(2.0 * 3.1415 * (float)x / 128.0));
    
                        newX = (x + xo);
                        newY = (y + yo);
    
                        if (newX > 0 && newX < nWidth)
                        { 
                            fp[x, y].X = (float)newX;
                            pt[x, y].X = (int)newX;
                        }
                        else
                        { 
                            fp[x, y].X = (float)0.0;
                            pt[x, y].X = 0;
                        }
    
    
                        if (newY > 0 && newY < nHeight)
                        { 
                            fp[x, y].Y = (float)newY;
                            pt[x, y].Y = (int)newY;
                        }
                        else
                        { 
                            fp[x, y].Y = (float)0.0;
                            pt[x, y].Y = 0;
                        }
                    }
    
    
                //进行合成
                Bitmap bSrc = (Bitmap)src.Clone();
    
                // 依照 Format24bppRgb 每三个表示一 Pixel 0: 蓝 1: 绿 2: 红
                BitmapData bitmapData = src.LockBits(new Rectangle(0, 0, src.Width, src.Height), ImageLockMode.ReadWrite,
                                               PixelFormat.Format24bppRgb);
                BitmapData bmSrc = bSrc.LockBits(new Rectangle(0, 0, bSrc.Width, bSrc.Height), ImageLockMode.ReadWrite,
                                                 PixelFormat.Format24bppRgb);
    
                int scanline = bitmapData.Stride;
    
                IntPtr Scan0 = bitmapData.Scan0;
                IntPtr SrcScan0 = bmSrc.Scan0;
    
                unsafe
                { 
                    byte* p = (byte*)(void*)Scan0;
                    byte* pSrc = (byte*)(void*)SrcScan0;
    
                    int nOffset = bitmapData.Stride - src.Width * 3;
    
                    int xOffset, yOffset;
    
                    for (int y = 0; y < nHeight; ++y)
                    { 
                        for (int x = 0; x < nWidth; ++x)
                        { 
                            xOffset = pt[x, y].X;
                            yOffset = pt[x, y].Y;
    
                            if (yOffset >= 0 && yOffset < nHeight && xOffset >= 0 && xOffset < nWidth)
                            { 
                                p[0] = pSrc[(yOffset * scanline) + (xOffset * 3)];
                                p[1] = pSrc[(yOffset * scanline) + (xOffset * 3) + 1];
                                p[2] = pSrc[(yOffset * scanline) + (xOffset * 3) + 2];
                            }
    
                            p += 3;
                        }
                        p += nOffset;
                    }
                }
    
                src.UnlockBits(bitmapData);
                bSrc.UnlockBits(bmSrc);
    
                return src;
            }
            #endregion
    
            #region 调整曝光度值
            /// <summary>
            /// 调整曝光度值
            /// </summary>
            /// <param name="src">原图</param>
            /// <param name="r"></param>
            /// <param name="g"></param>
            /// <param name="b"></param>
            /// <returns></returns>
            public Bitmap AdjustGamma(Bitmap src, double r, double g, double b)
            { 
                // 判断是不是在0.2~5 之间
                r = Math.Min(Math.Max(0.2, r), 5);
                g = Math.Min(Math.Max(0.2, g), 5);
                b = Math.Min(Math.Max(0.2, b), 5);
    
                // 依照 Format24bppRgb 每三个表示一 Pixel 0: 蓝 1: 绿 2: 红
                BitmapData bitmapData = src.LockBits(new Rectangle(0, 0, src.Width, src.Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
    
                unsafe
                { 
                    // 抓住第一个 Pixel 第一个数值
                    byte* p = (byte*)(void*)bitmapData.Scan0;
    
                    // 跨步值 - 宽度 *3 可以算出畸零地 之后跳到下一行
                    int nOffset = bitmapData.Stride - src.Width * 3;
    
                    for (int y = 0; y < src.Height; y++)
                    { 
                        for (int x = 0; x < src.Width; x++)
                        { 
                            p[2] = (byte)Math.Min(255, (int)((255.0 * Math.Pow(p[2] / 255.0, 1.0 / r)) + 0.5));
                            p[1] = (byte)Math.Min(255, (int)((255.0 * Math.Pow(p[1] / 255.0, 1.0 / g)) + 0.5));
                            p[0] = (byte)Math.Min(255, (int)((255.0 * Math.Pow(p[0] / 255.0, 1.0 / b)) + 0.5));
    
    
                            // 跳去下一个 Pixel
                            p += 3;
    
                        }
                        // 跨越畸零地
                        p += nOffset;
                    }
                }
                src.UnlockBits(bitmapData);
                return src;
    
            }
            #endregion
    
            #region 高对比,对过深的颜色调浅，过浅的颜色调深。
            /// <summary>
            /// 高对比,对过深的颜色调浅，过浅的颜色调深。
            /// </summary>
            /// <param name="src"></param>
            /// <param name="effectThreshold"> 高对比程度 -100~100</param>
            /// <returns></returns>
            public Bitmap Contrast(Bitmap src, float effectThreshold)
            { 
    
                // 依照 Format24bppRgb 每三个表示一 Pixel 0: 蓝 1: 绿 2: 红
                BitmapData bitmapData = src.LockBits(new Rectangle(0, 0, src.Width, src.Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
    
                // 判断是否在 -100~100
                effectThreshold = effectThreshold < -100 ? -100 : effectThreshold;
                effectThreshold = effectThreshold > 100 ? 100 : effectThreshold;
    
                effectThreshold = (float)((100.0 + effectThreshold) / 100.0);
                effectThreshold *= effectThreshold;
    
                unsafe
                { 
                    // 抓住第一个 Pixel 第一个数值 www.it165.net
                    byte* p = (byte*)(void*)bitmapData.Scan0;
    
                    // 跨步值 - 宽度 *3 可以算出畸零地 之后跳到下一行
                    int nOffset = bitmapData.Stride - src.Width * 3;
    
    
    
                    for (int y = 0; y < src.Height; y++)
                    { 
                        for (int x = 0; x < src.Width; x++)
                        { 
                            double buffer = 0;
    
    
                            // 公式 (Red/255)-0.5= 偏离中间值程度
                            // ((偏离中间值程度 * 影响范围)+0.4 ) * 255
                            buffer = ((((p[2] / 255.0) - 0.5) * effectThreshold) + 0.5) * 255.0;
                            buffer = buffer > 255 ? 255 : buffer;
                            buffer = buffer < 0 ? 0 : buffer;
                            p[2] = (byte)buffer;
    
                            buffer = ((((p[1] / 255.0) - 0.5) * effectThreshold) + 0.5) * 255.0;
                            buffer = buffer > 255 ? 255 : buffer;
                            buffer = buffer < 0 ? 0 : buffer;
                            p[1] = (byte)buffer;
    
    
                            buffer = ((((p[0] / 255.0) - 0.5) * effectThreshold) + 0.5) * 255.0;
                            buffer = buffer > 255 ? 255 : buffer;
                            buffer = buffer < 0 ? 0 : buffer;
                            p[0] = (byte)buffer;
    
    
    
    
                            // 跳去下一个 Pixel
                            p += 3;
    
                        }
                        // 跨越畸零地
                        p += nOffset;
                    }
                }
                src.UnlockBits(bitmapData);
                return src;
    
    
            }
            #endregion
    
            #region 对图片进行雾化效果
            /// <summary>
            /// 对图片进行雾化效果
            /// </summary>
            /// <param name="bmp"></param>
            /// <returns></returns>
            public Bitmap Atomization(Bitmap bmp)
            { 
    
                int Height = bmp.Height;
                int Width = bmp.Width;
                Bitmap newBitmap = new Bitmap(Width, Height);
                Bitmap oldBitmap = bmp;
                Color pixel;
                for (int x = 1; x < Width - 1; x++)
                { 
                    for (int y = 1; y < Height - 1; y++)
                    { 
                        Random MyRandom = new Random(Guid.NewGuid().GetHashCode());
                        int k = MyRandom.Next(123456);
                        //像素块大小
                        int dx = x + k % 19;
                        int dy = y + k % 19;
                        if (dx >= Width)
                            dx = Width - 1;
                        if (dy >= Height)
                            dy = Height - 1;
                        pixel = oldBitmap.GetPixel(dx, dy);
                        newBitmap.SetPixel(x, y, pixel);
                    }
                }
                return newBitmap;
            }
            #endregion
    
            public MemoryStream test(MemoryStream target)
            { 
                Graphics dc = null;
                Bitmap bit = new Bitmap(200, 200);
                //写字符串
                dc = Graphics.FromImage(bit);
                //dc.SmoothingMode = SmoothingMode.HighQuality;
                //dc.TextRenderingHint = TextRenderingHint.ClearTypeGridFit; ;
                //dc.InterpolationMode = InterpolationMode.HighQualityBilinear;
                //dc.CompositingQuality = CompositingQuality.HighQuality;
    
                dc.Clear(Color.White);
                //画验证码背景，例如，增加早点，添加曲线和直线等
                dc.DrawImageUnscaled(DrawBackground(), 0, 0);
    
                bit.Save(target, ImageFormat.Gif);
                //brush.Dispose();
                bit.Dispose();
                dc.Dispose();
                return target;
    
            }
    
        } //END Class DrawValidationCode
        #endregion

### 3、高斯模糊算法类 ###

在验证码生成类中调用了该算法；

#region 高斯模糊算法
        /// <summary>
        /// 高斯模糊算法
        /// </summary>
        public class GaussianHelper
        { 
            public static double[,] Calculate1DSampleKernel(double deviation, int size)
            { 
                double[,] ret = new double[size, 1];
                double sum = 0;
                int half = size / 2;
                for (int i = 0; i < size; i++)
                { 
                    ret[i, 0] = 1 / (Math.Sqrt(2 * Math.PI) * deviation) * Math.Exp(-(i - half) * (i - half) / (2 * deviation * deviation));
                    sum += ret[i, 0];
                }
                return ret;
            }
            public static double[,] Calculate1DSampleKernel(double deviation)
            { 
                int size = (int)Math.Ceiling(deviation * 3) * 2 + 1;
                return Calculate1DSampleKernel(deviation, size);
            }
            public static double[,] CalculateNormalized1DSampleKernel(double deviation)
            { 
                return NormalizeMatrix(Calculate1DSampleKernel(deviation));
            }
            public static double[,] NormalizeMatrix(double[,] matrix)
            { 
                double[,] ret = new double[matrix.GetLength(0), matrix.GetLength(1)];
                double sum = 0;
                for (int i = 0; i < ret.GetLength(0); i++)
                { 
                    for (int j = 0; j < ret.GetLength(1); j++)
                        sum += matrix[i, j];
                }
                if (sum != 0)
                { 
                    for (int i = 0; i < ret.GetLength(0); i++)
                    { 
                        for (int j = 0; j < ret.GetLength(1); j++)
                            ret[i, j] = matrix[i, j] / sum;
                    }
                }
                return ret;
            }
            public static double[,] GaussianConvolution(double[,] matrix, double deviation)
            { 
                double[,] kernel = CalculateNormalized1DSampleKernel(deviation);
                double[,] res1 = new double[matrix.GetLength(0), matrix.GetLength(1)];
                double[,] res2 = new double[matrix.GetLength(0), matrix.GetLength(1)];
                //x-direction
                for (int i = 0; i < matrix.GetLength(0); i++)
                { 
                    for (int j = 0; j < matrix.GetLength(1); j++)
                        res1[i, j] = processPoint(matrix, i, j, kernel, 0);
                }
                //y-direction
                for (int i = 0; i < matrix.GetLength(0); i++)
                { 
                    for (int j = 0; j < matrix.GetLength(1); j++)
                        res2[i, j] = processPoint(res1, i, j, kernel, 1);
                }
                return res2;
            }
            private static double processPoint(double[,] matrix, int x, int y, double[,] kernel, int direction)
            { 
                double res = 0;
                int half = kernel.GetLength(0) / 2;
                for (int i = 0; i < kernel.GetLength(0); i++)
                { 
                    int cox = direction == 0 ? x + i - half : x;
                    int coy = direction == 1 ? y + i - half : y;
                    if (cox >= 0 && cox < matrix.GetLength(0) && coy >= 0 && coy < matrix.GetLength(1))
                    { 
                        res += matrix[cox, coy] * kernel[i, 0];
                    }
                }
                return res;
            }
            /// <summary>
            /// 对颜色值进行灰色处理
            /// </summary>
            /// <param name="cr"></param>
            /// <returns></returns>
            private Color grayscale(Color cr)
            { 
                return Color.FromArgb(cr.A, (int)(cr.R * .3 + cr.G * .59 + cr.B * 0.11),
                   (int)(cr.R * .3 + cr.G * .59 + cr.B * 0.11),
                  (int)(cr.R * .3 + cr.G * .59 + cr.B * 0.11));
            }
            /// <summary>
            /// 对图片进行高斯模糊
            /// </summary>
            /// <param name="d">模糊数值，数值越大模糊越很</param>
            /// <param name="image">一个需要处理的图片</param>
            /// <returns></returns>
            public Bitmap FilterProcessImage(double d, Bitmap image)
            { 
                Bitmap ret = new Bitmap(image.Width, image.Height);
                Double[,] matrixR = new Double[image.Width, image.Height];
                Double[,] matrixG = new Double[image.Width, image.Height];
                Double[,] matrixB = new Double[image.Width, image.Height];
                for (int i = 0; i < image.Width; i++)
                { 
                    for (int j = 0; j < image.Height; j++)
                    { 
                        //matrix[i, j] = grayscale(image.GetPixel(i, j)).R;
                        matrixR[i, j] = image.GetPixel(i, j).R;
                        matrixG[i, j] = image.GetPixel(i, j).G;
                        matrixB[i, j] = image.GetPixel(i, j).B;
                    }
                }
                matrixR = GaussianHelper.GaussianConvolution(matrixR, d);
                matrixG = GaussianHelper.GaussianConvolution(matrixG, d);
                matrixB = GaussianHelper.GaussianConvolution(matrixB, d);
                for (int i = 0; i < image.Width; i++)
                { 
                    for (int j = 0; j < image.Height; j++)
                    { 
                        Int32 R = (int)Math.Min(255, matrixR[i, j]);
                        Int32 G = (int)Math.Min(255, matrixG[i, j]);
                        Int32 B = (int)Math.Min(255, matrixB[i, j]);
                        ret.SetPixel(i, j, Color.FromArgb(R, G, B));
                    }
                }
                return ret;
            }
            
    
        }
        #endregion

## \#参考 ##

[https://www.cnblogs.com/wangqiideal/articles/9238787.html][https_www.cnblogs.com_wangqiideal_articles_9238787.html]

## \#注意 ##

因代码中涉及到与C++的dll交互，需要将类所在的程序集设置 “允许不安全代码”，否则会编译失败；  
![设置“允许不安全代码”][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dpbGxpbmd0b2xvdmU_size_16_color_FFFFFF_t_70]  
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博客园同步更新地址：[https://www.cnblogs.com/willingtolove/p/11234748.html][https_www.cnblogs.com_willingtolove_p_11234748.html]  
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[2019072316011554.png]: https://img-blog.csdnimg.cn/2019072316011554.png
[20190723213211325.png]: /images/20211126/fef49c8922c14371b2ecadfd552bea15.png
[https_www.cnblogs.com_wangqiideal_articles_9238787.html]: https://www.cnblogs.com/wangqiideal/articles/9238787.html
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[https_www.cnblogs.com_willingtolove_p_11234748.html]: https://www.cnblogs.com/willingtolove/p/11234748.html