如何在 C# 项目中实现和执行 OCR？
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How to implement and do OCR in a C# project?
提问by Berker Yüceer
I ve been searching for a while and all that i ve seen some OCR library requests. I would like to know how to implement the purest, easy to install and use OCR library with detailed info for installation into a C# project.
我已经搜索了一段时间，我看到了一些 OCR 库请求。我想知道如何实现最简单、易于安装和使用的 OCR 库，其中包含安装到 C# 项目的详细信息。
If posible, I just wanna implement it like a usual dll reference...
如果可能的话，我只想像通常的 dll 引用一样实现它......
Example:
例子：
using org.pdfbox.pdmodel;
using org.pdfbox.util;
Also a little OCR code example would be nice, such as:
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;
}
So please consider that I'm not familiar to OCR projects and give me an answer like talking to a dummy.
所以请考虑我对 OCR 项目不熟悉，并给我一个答案，就像与假人交谈一样。
Edit:I guess people misunderstood my request. I wanted to know how to implement those open source OCR libraries to a C# project and how to use them. The link given as dup is not giving answers that I requested at all.
编辑：我想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。
采纳答案by B.K.
If anyone is looking into this, I've been trying different options and the following approach yields very good results. The following are the steps to get a working example:
如果有人在研究这个，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：
- Add .NET Wrapper for tesseractto your project. It can be added via NuGet package
Install-Package Tesseract(https://github.com/charlesw/tesseract). - Go to the Downloadssection of the official Tesseractproject (https://code.google.com/p/tesseract-ocr/EDIT:It's now located here: https://github.com/tesseract-ocr/langdata).
- Download the preferred language data, example:
tesseract-ocr-3.02.eng.tar.gz English language data for Tesseract 3.02. - Create
tessdatadirectory in your project and place the language data files in it. - Go to
Propertiesof the newly added files and set them to copy on build. - Add a reference to
System.Drawing. - From .NET Wrapper repository, in the
Samplesdirectory copy the samplephototest.tiffile into your project directory and set it to copy on build. - Create the following two files in your project (just to get started):
- 将.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。 - 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：https: //github.com/tesseract-ocr/langdata）。
- 下载首选语言数据，例如：
tesseract-ocr-3.02.eng.tar.gz English language data for Tesseract 3.02. tessdata在您的项目中创建目录并将语言数据文件放入其中。- 转到
Properties新添加的文件并将它们设置为在构建时复制。 - 添加对
System.Drawing. - 从 .NET Wrapper 存储库，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。 - 在您的项目中创建以下两个文件（只是为了开始）：
Program.cs
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));
}
}
}
}
FormattedConsoleLogger.cs
FormattedConsoleLogger.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;
}
}
}
}
回答by Rob P.
Here's one: (check out http://hongouru.blogspot.ie/2011/09/c-ocr-optical-character-recognition.htmlor http://www.codeproject.com/Articles/41709/How-To-Use-Office-2007-OCR-Using-Cfor more info)
这是一个：（查看http://hongouru.blogspot.ie/2011/09/c-ocr-optical-character-recognition.html或http://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.
}
}
回答by Ben Walker
I'm using tesseract OCR engine with TessNet2 (a C# wrapper - http://www.pixel-technology.com/freeware/tessnet2/).
我正在使用 TessNet2（一个 C# 包装器 - http://www.pixel-technology.com/freeware/tessnet2/）的tesseract OCR 引擎。
Some basic code:
一些基本代码：
using tessnet2;
...
...
Bitmap image = new Bitmap(@"u:\user files\bwalker49257.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";
}
回答by Jimmy
Some online API's work pretty well: ocr.spaceand Google Cloud Vision. Both of these are free, as long as you do less than 1000 OCR's per month. You can drag & drop an image to do a quick manual test to see how they perform for your images.
一些在线 API 工作得很好：ocr.space和Google Cloud Vision。只要您每月执行的 OCR 少于 1000 次，这两者都是免费的。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表现。
I find OCR.space easier to use (no messing around with nuget libraries), but, for my purpose, Google Cloud Vision provided slightly better results than OCR.space.
我发现 OCR.space 更易于使用（不会与 nuget 库混淆），但是，就我而言，Google Cloud Vision 提供的结果略好于 OCR.space。
Google Cloud Vision example:
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 example:
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;
