How to implement and do OCR in a C# project?
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.
If posible, I just wanna implement it like a usual dll reference...
Example:
using org.pdfbox.pdmodel;
using org.pdfbox.util;
Also a little OCR code example would be nice, such as:
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.
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.
Answer
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:
- Add .NET Wrapper for tesseract to your project. It can be added via NuGet package
Install-Package Tesseract(https://github.com/charlesw/tesseract). - Go to the Downloads section of the official Tesseract project (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):
Program.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
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;
}
}
}
}