提高防OCR的一种办法

Posted 2021-07-01 小隐的博客

今天因为某件事情，想搞个图片，想防止被OCR。

 

各种试，但不得不说现在的OCR真的牛啊，变形，加噪，横线，仍然难以阻挡。

后面试了不下百十来种字体，但仍然无效，比如下面的

 

 

也试了一种简单办法 ，有点小用，但也没大用

 

 

 

但最后试出一种结果，可以有效的防止OCR（只是目前），拿三家大厂来试一下

腾讯

https://cloud.tencent.com/product/ocr-catalog

 

 

 

 

 

百度

https://cloud.baidu.com/product/ocr/general

 

 

 

阿里

https://duguang.aliyun.com/experience?type=universal&subtype=general#intro

 

 

这个字体是怎么生成的了，很简单

生成汉字，扭曲，加棱形外框，旋转20度。

不知道哪位民间高手，能够试试？

 

另外把生成验证码的各种操作C#代码放出来，凑合看，跟本文关系不大

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace wxEncode
{
    public partial class Form1 : Form
    {
        //private static Color BackColor = Color.White;
        private static int Width = 62;
        private static int Height = 61;
        private Random _random;
        //private int _brushNameIndex;
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            
            string code = "今";
            //code = "wwwwsss.coa.domf";
            //code = "wwwww.baidu.com";
            Width = getstrLen(code);
            pictureBox1.Image = GetVCode(code);

            Bitmap b= TwistImage(new Bitmap(pictureBox1.Image), true, Convert.ToInt32( numericUpDown1.Value), Convert.ToInt32(numericUpDown2.Value));
            Image img = b;
            //System.IO.File.Delete(@"d:\\x.png");
            //b.Save(@"d:\\x.png");
            pictureBox1.Image = b;
        }
        public int getstrLen(string code)
        {
            code = code.Trim();
            string d = "`1234567890-=qwertyuiop[]\\\\asdfghjkl;\'zxcvbnm,./~!@#$%^&*()_+QWERTYUIOP{}|ASDFGHJKL:\\"ZXCVBNM<>?";
            int r = 0;
            int e = 0;
            int h = 0;
            for (int i = 0; i < code.Length; i++)
            {
                if (d.Contains(code[i]))
                {
                    //r += 15;
                    e++;
                }
                else
                {
                    //r += 20;
                    h++;
                }

            }
            
            int s1 = 6;
            if (e < s1)
                r += e * 40;
            else
                r += e * 28;
            if (h < s1)
                r += h * 60;
            else
                r += h * 45;
            //if (code.Length<=s1)
            //    if (e>=2)
            //        r +=    (s1+1- e)*10;
            
            return r;
        }
        public Image GetVCode(string codeStr)
        {
            _random = new Random();
            using (Bitmap img = new Bitmap(Width, Height))
            {
                // _code = GetRandomCode();
                // System.Web.HttpContext.Current.Session["vcode"] = _code;
                using (Graphics g = Graphics.FromImage(img))
                {
                    g.Clear(Color.White);//绘画背景颜色

                    Paint_Text(g, codeStr);// 绘画文字
                    // g.DrawString(strCode, new Font("微软雅黑", 15), Brushes.Blue, new PointF(5, 2));// 绘画文字
                    //Paint_TextStain(img);// 绘画噪音点
                    Paint_line(g);
                    g.DrawRectangle(Pens.DarkGray, 0, 0, Width - 1, Height - 1);//绘画边框
                    IntPtr pr = img.GetHbitmap();
                    Image MyImage = Image.FromHbitmap(pr);
                    return MyImage;
                    //using (System.IO.MemoryStream ms = new System.IO.MemoryStream())
                    //{
                    //    //将图片 保存到内存流中
                    //    img.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
                    //    //将内存流 里的 数据  转成 byte 数组 返回
                    //    return ms.ToArray();
                    //}
                }
            }

        }
        private void Paint_line(Graphics graph)
        {
            return;
            int nLines = 3;
            
            System.Drawing.Pen pen = new System.Drawing.Pen(GetBrush(),  0.5f);
            for (int a = 0; a < nLines; a++)
            {
                int x1 = _random.Next() % Convert.ToInt32 (Width/4);
                int y1 = _random.Next() % Height;
                int x2 = _random.Next() % Convert.ToInt32(Width / 4*3);
                int y2 = _random.Next() % Height;
                graph.DrawLine(pen, x1, y1, x2, y2);
            }
        }
        /// <summary>
        /// 绘画文字
        /// </summary>
        /// <param name="g"></param>
        private void Paint_Text(Graphics g, string code)
        {
            g.DrawString(code, GetFont(), GetBrush(), 3, 1);
        }

        /// <summary>
        /// 绘画文字噪音点
        /// </summary>
        /// <param name="g"></param>
        private void Paint_TextStain(Bitmap b)
        {
            string[] BrushName = new string[] {    "OliveDrab",
                                                  "ForestGreen",
                                                  "DarkCyan",
                                                  "LightSlateGray",
                                                  "RoyalBlue",
                                                  "SlateBlue",
                                                  "DarkViolet",
                                                  "MediumVioletRed",
                                                  "IndianRed",
                                                  "Firebrick",
                                                  "Chocolate",
                                                  "Peru",
                                                  " enrod"
                                             };

            for (int n = 0; n < Width*Height*0.05; n++)
            {
                int bi = _random.Next(0, BrushName.Length);
                int x = _random.Next(Width);
                int y = _random.Next(Height);
                b.SetPixel(x, y, Color.FromName(BrushName[bi]));
                

            }

        }
        /// <summary>
        /// 随机取一个字体
        /// </summary>
        /// <returns></returns>
        private Font GetFont()
        {
            string[] FontItems = new string[]{   "Arial",
                                                  "Helvetica",
                                                  "Geneva",
                                                  "sans-serif",
                                                  "Verdana"
                                              };

            int fontIndex = _random.Next(0, FontItems.Length);
            FontStyle fontStyle = GetFontStyle(_random.Next(0, 2));
            Console.WriteLine("font:" + FontItems[fontIndex]);
            return new Font(FontItems[4], 25, fontStyle);
        }
        /**/
        /**/
        /**/
        /// <summary>
        /// 随机取一个笔刷
        /// </summary>
        /// <returns></returns>
        private Brush GetBrush()
        {
            Brush[] BrushItems = new Brush[]{     Brushes.OliveDrab,
                                                  Brushes.ForestGreen,
                                                  Brushes.DarkCyan,
                                                  Brushes.LightSlateGray,
                                                  Brushes.RoyalBlue,
                                                  Brushes.SlateBlue,
                                                  Brushes.DarkViolet,
                                                  Brushes.MediumVioletRed,
                                                  Brushes.IndianRed,
                                                  Brushes.Firebrick,
                                                  Brushes.Chocolate,
                                                  Brushes.Peru,
                                                  Brushes.Goldenrod
                                            };

            int brushIndex = _random.Next(0, BrushItems.Length);
            Console.WriteLine("brush:" + brushIndex.ToString () +"--" + BrushItems[brushIndex]);
            return BrushItems[7];
        }
        /// <summary>
        /// 绘画背景颜色
        /// </summary>
        /// <param name="g"></param>
        private void Paint_Background(Graphics g)
        {
            g.Clear(Color.White);
        }
        /**/
        /**/
        /**/
        /// <summary>
        /// 取一个字体的样式
        /// </summary>
        /// <param name="index"></param>
        /// <returns></returns>
        private FontStyle GetFontStyle(int index)
        {
            index = 0;
            switch (index)
            {
                case 0:
                    return FontStyle.Bold;
                case 1:
                    return FontStyle.Italic;
                default:
                    return FontStyle.Regular;
            }
        }

        /// <summary>
        /// 取得一个 4 位的随机码
        /// </summary>
        /// <returns></returns>
        public string GetRandomCode()
        {
            return Guid.NewGuid().ToString().Substring(0, 5);
        }

        private const double PI = 3.1415926535897932384626433832795;
        private const double PI2 = 6.283185307179586476925286766559;

        /// <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 System.Drawing.Bitmap TwistImage(Bitmap srcBmp, bool bXDir, double dMultValue, double dPhase)
        {
            System.Drawing.Bitmap destBmp = new Bitmap(srcBmp.Width, srcBmp.Height);

            //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;
        }


    }
}