52

我已经搜索了一段时间,并且我看到了一些 OCR 库请求。我想知道如何实现最纯粹、易于安装和使用带有详细信息的 OCR 库以安装到 C# 项目中。

如果可能的话,我只想像通常的 dll 引用一样实现它......

例子:

using org.pdfbox.pdmodel;
using org.pdfbox.util;

还有一个小的 OCR 代码示例会很好,例如:

public string OCRFromBitmap(Bitmap Bmp)
{
    Bmp.Save(temppath, System.Drawing.Imaging.ImageFormat.Tiff);
    string OcrResult = Analyze(temppath);
    File.Delete(temppath);
    return OcrResult;
}

因此,请考虑到我对 OCR 项目并不熟悉,并给我一个类似于与假人交谈的答案。

编辑: 我猜人们误解了我的要求。我想知道如何将这些开源 OCR 库实现到 C# 项目以及如何使用它们。作为 dup 给出的链接根本没有给出我要求的答案。

4

4 回答 4

120

如果有人正在研究这个,我一直在尝试不同的选择,下面的方法产生了非常好的结果。以下是获取工作示例的步骤:

  1. .NET Wrapper for tesseract添加到您的项目中。它可以通过 NuGet 包Install-Package Tesseract( https://github.com/charlesw/tesseract ) 添加。
  2. 转到官方Tesseract项目的下载部分( https://code.google.com/p/tesseract-ocr/编辑: 它现在位于此处:https ://github.com/tesseract-ocr/langdata )。
  3. 下载首选语言数据,例如:tesseract-ocr-3.02.eng.tar.gz English language data for Tesseract 3.02.
  4. 在您的项目中创建tessdata目录并将语言数据文件放入其中。
  5. 转到Properties新添加的文件并将它们设置为在构建时复制。
  6. 添加对System.Drawing.
  7. 从 .NET Wrapper 存储库中,在Samples目录中将示例phototest.tif文件复制到您的项目目录中,并将其设置为在构建时复制。
  8. 在您的项目中创建以下两个文件(只是为了开始):

程序.cs

using System;
using Tesseract;
using System.Diagnostics;

namespace ConsoleApplication
{
    class Program
    {
        public static void Main(string[] args)
        {
            var testImagePath = "./phototest.tif";
            if (args.Length > 0)
            {
                testImagePath = args[0];
            }

            try
            {
                var logger = new FormattedConsoleLogger();
                var resultPrinter = new ResultPrinter(logger);
                using (var engine = new TesseractEngine(@"./tessdata", "eng", EngineMode.Default))
                {
                    using (var img = Pix.LoadFromFile(testImagePath))
                    {
                        using (logger.Begin("Process image"))
                        {
                            var i = 1;
                            using (var page = engine.Process(img))
                            {
                                var text = page.GetText();
                                logger.Log("Text: {0}", text);
                                logger.Log("Mean confidence: {0}", page.GetMeanConfidence());

                                using (var iter = page.GetIterator())
                                {
                                    iter.Begin();
                                    do
                                    {
                                        if (i % 2 == 0)
                                        {
                                            using (logger.Begin("Line {0}", i))
                                            {
                                                do
                                                {
                                                    using (logger.Begin("Word Iteration"))
                                                    {
                                                        if (iter.IsAtBeginningOf(PageIteratorLevel.Block))
                                                        {
                                                            logger.Log("New block");
                                                        }
                                                        if (iter.IsAtBeginningOf(PageIteratorLevel.Para))
                                                        {
                                                            logger.Log("New paragraph");
                                                        }
                                                        if (iter.IsAtBeginningOf(PageIteratorLevel.TextLine))
                                                        {
                                                            logger.Log("New line");
                                                        }
                                                        logger.Log("word: " + iter.GetText(PageIteratorLevel.Word));
                                                    }
                                                } while (iter.Next(PageIteratorLevel.TextLine, PageIteratorLevel.Word));
                                            }
                                        }
                                        i++;
                                    } while (iter.Next(PageIteratorLevel.Para, PageIteratorLevel.TextLine));
                                }
                            }
                        }
                    }
                }
            }
            catch (Exception e)
            {
                Trace.TraceError(e.ToString());
                Console.WriteLine("Unexpected Error: " + e.Message);
                Console.WriteLine("Details: ");
                Console.WriteLine(e.ToString());
            }
            Console.Write("Press any key to continue . . . ");
            Console.ReadKey(true);
        }



        private class ResultPrinter
        {
            readonly FormattedConsoleLogger logger;

            public ResultPrinter(FormattedConsoleLogger logger)
            {
                this.logger = logger;
            }

            public void Print(ResultIterator iter)
            {
                logger.Log("Is beginning of block: {0}", iter.IsAtBeginningOf(PageIteratorLevel.Block));
                logger.Log("Is beginning of para: {0}", iter.IsAtBeginningOf(PageIteratorLevel.Para));
                logger.Log("Is beginning of text line: {0}", iter.IsAtBeginningOf(PageIteratorLevel.TextLine));
                logger.Log("Is beginning of word: {0}", iter.IsAtBeginningOf(PageIteratorLevel.Word));
                logger.Log("Is beginning of symbol: {0}", iter.IsAtBeginningOf(PageIteratorLevel.Symbol));

                logger.Log("Block text: \"{0}\"", iter.GetText(PageIteratorLevel.Block));
                logger.Log("Para text: \"{0}\"", iter.GetText(PageIteratorLevel.Para));
                logger.Log("TextLine text: \"{0}\"", iter.GetText(PageIteratorLevel.TextLine));
                logger.Log("Word text: \"{0}\"", iter.GetText(PageIteratorLevel.Word));
                logger.Log("Symbol text: \"{0}\"", iter.GetText(PageIteratorLevel.Symbol));
            }
        }
    }
}

格式化控制台记录器.cs

using System;
using System.Collections.Generic;
using System.Text;
using Tesseract;

namespace ConsoleApplication
{
    public class FormattedConsoleLogger
    {
        const string Tab = "    ";
        private class Scope : DisposableBase
        {
            private int indentLevel;
            private string indent;
            private FormattedConsoleLogger container;

            public Scope(FormattedConsoleLogger container, int indentLevel)
            {
                this.container = container;
                this.indentLevel = indentLevel;
                StringBuilder indent = new StringBuilder();
                for (int i = 0; i < indentLevel; i++)
                {
                    indent.Append(Tab);
                }
                this.indent = indent.ToString();
            }

            public void Log(string format, object[] args)
            {
                var message = String.Format(format, args);
                StringBuilder indentedMessage = new StringBuilder(message.Length + indent.Length * 10);
                int i = 0;
                bool isNewLine = true;
                while (i < message.Length)
                {
                    if (message.Length > i && message[i] == '\r' && message[i + 1] == '\n')
                    {
                        indentedMessage.AppendLine();
                        isNewLine = true;
                        i += 2;
                    }
                    else if (message[i] == '\r' || message[i] == '\n')
                    {
                        indentedMessage.AppendLine();
                        isNewLine = true;
                        i++;
                    }
                    else
                    {
                        if (isNewLine)
                        {
                            indentedMessage.Append(indent);
                            isNewLine = false;
                        }
                        indentedMessage.Append(message[i]);
                        i++;
                    }
                }

                Console.WriteLine(indentedMessage.ToString());

            }

            public Scope Begin()
            {
                return new Scope(container, indentLevel + 1);
            }

            protected override void Dispose(bool disposing)
            {
                if (disposing)
                {
                    var scope = container.scopes.Pop();
                    if (scope != this)
                    {
                        throw new InvalidOperationException("Format scope removed out of order.");
                    }
                }
            }
        }

        private Stack<Scope> scopes = new Stack<Scope>();

        public IDisposable Begin(string title = "", params object[] args)
        {
            Log(title, args);
            Scope scope;
            if (scopes.Count == 0)
            {
                scope = new Scope(this, 1);
            }
            else
            {
                scope = ActiveScope.Begin();
            }
            scopes.Push(scope);
            return scope;
        }

        public void Log(string format, params object[] args)
        {
            if (scopes.Count > 0)
            {
                ActiveScope.Log(format, args);
            }
            else
            {
                Console.WriteLine(String.Format(format, args));
            }
        }

        private Scope ActiveScope
        {
            get
            {
                var top = scopes.Peek();
                if (top == null) throw new InvalidOperationException("No current scope");
                return top;
            }
        }
    }
}
于 2014-12-09T17:32:48.537 回答
12

这是一个:(查看http://hongouru.blogspot.ie/2011/09/c-ocr-optical-character-recognition.htmlhttp://www.codeproject.com/Articles/41709/How-To-使用-Office-2007-OCR-Using-C了解更多信息)

using MODI;
static void Main(string[] args)
{
    DocumentClass myDoc = new DocumentClass();
    myDoc.Create(@"theDocumentName.tiff"); //we work with the .tiff extension
    myDoc.OCR(MiLANGUAGES.miLANG_ENGLISH, true, true);

    foreach (Image anImage in myDoc.Images)
    {
        Console.WriteLine(anImage.Layout.Text); //here we cout to the console.
    }
}
于 2012-06-08T10:57:04.857 回答
6

我正在使用带有 TessNet2 的 tesseract OCR 引擎(一个 C# 包装器 - http://www.pixel-technology.com/freeware/tessnet2/)。

一些基本代码:

using tessnet2;

...

Bitmap image = new Bitmap(@"u:\user files\bwalker\2849257.tif");
            tessnet2.Tesseract ocr = new tessnet2.Tesseract();
            ocr.SetVariable("tessedit_char_whitelist", "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz.,$-/#&=()\"':?"); // Accepted characters
            ocr.Init(@"C:\Users\bwalker\Documents\Visual Studio 2010\Projects\tessnetWinForms\tessnetWinForms\bin\Release\", "eng", false); // Directory of your tessdata folder
            List<tessnet2.Word> result = ocr.DoOCR(image, System.Drawing.Rectangle.Empty);
            string Results = "";
            foreach (tessnet2.Word word in result)
            {
                Results += word.Confidence + ", " + word.Text + ", " + word.Left + ", " + word.Top + ", " + word.Bottom + ", " + word.Right + "\n";
            }
于 2012-06-08T21:22:52.460 回答
3

一些在线 API 运行良好:ocr.spaceGoogle Cloud Vision。只要您每月执行的 OCR 少于 1000 个,这两个都是免费的。您可以拖放图像以进行快速手动测试,以查看它们对您的图像的执行情况。

我发现 OCR.space 更易于使用(不要乱用 nuget 库),但就我的目的而言,Google Cloud Vision 提供的结果略好于 OCR.space。

谷歌云视觉示例:

GoogleCredential cred = GoogleCredential.FromJson(json);
Channel channel = new Channel(ImageAnnotatorClient.DefaultEndpoint.Host, ImageAnnotatorClient.DefaultEndpoint.Port, cred.ToChannelCredentials());
ImageAnnotatorClient client = ImageAnnotatorClient.Create(channel);
Image image = Image.FromStream(stream);

EntityAnnotation googleOcrText = client.DetectText(image).First();
Console.Write(googleOcrText.Description);

OCR.space 示例:

string uri = $"https://api.ocr.space/parse/imageurl?apikey=helloworld&url={imageUri}";
string responseString = WebUtilities.DoGetRequest(uri);
OcrSpaceResult result = JsonConvert.DeserializeObject<OcrSpaceResult>(responseString);
if ((!result.IsErroredOnProcessing) && !String.IsNullOrEmpty(result.ParsedResults[0].ParsedText))
  return result.ParsedResults[0].ParsedText;
于 2018-12-27T19:04:37.700 回答