Perform OCR in Windows

11 Jan 20234 minutes to read

The Syncfusion .NET OCR library used to extract text from scanned PDFs and images in Windows Forms application with the help of Google’s Tesseract Optical Character Recognition engine.

Steps to perform OCR on entire PDF document in Windows Forms

Step 1: Create a new Windows Forms application project.

In project configuration window, name your project and select Create.

Step 2: Install the Syncfusion.Pdf.OCR.WinForms NuGet package as a reference to your WinForms application from nuget.org.

Step 3: Tesseract assemblies are not added as a reference. They must be kept in the local machine, and the assemblies location is passed as a parameter to the OCR processor.

C#

OCRProcessor processor = new OCRProcessor(@"TesseractBinaries/")

Step 4: Place the Tesseract language data {e.g, eng.traineddata} in the local system and provide a path to the OCR processor. Please use the OCR language data for other languages using the following link.

Tesseract language data

C#

OCRProcessor processor = new OCRProcessor("Tesseractbinaries/");
processor.PerformOCR(loadedDocument, "tessdata/");

Step 5: Add a new button in Form1.Designer.cs file.

C#

private System.Windows.Forms.Button button1;

private void InitializeComponent()
{
    this.button1 = new System.Windows.Forms.Button();
    this.SuspendLayout();
    // 
    // button1
    // 
    this.button1.Location = new System.Drawing.Point(284, 162);
    this.button1.Name = "button1";
    this.button1.Size = new System.Drawing.Size(190, 65);
    this.button1.TabIndex = 0;
    this.button1.Text = "Perform OCR on entire PDF document";
    this.button1.UseVisualStyleBackColor = true;
    this.button1.Click += new System.EventHandler(this.btnCreate_Click);
    // 
    // Form1
    // 
    this.AutoScaleDimensions = new System.Drawing.SizeF(9F, 20F);
    this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
    this.ClientSize = new System.Drawing.Size(800, 450);
    this.Controls.Add(this.button1);
    this.Name = "Form1";
    this.Text = "Form1";
    this.ResumeLayout(false);
}

Step 6: Include the following namespaces in the Form1.cs file.

C#

using Syncfusion.OCRProcessor;
using Syncfusion.Pdf.Parsing;

Step 7: Create the btnCreate_Click event and add the following code to perform OCR on the entire PDF document using PerformOCR method of the OCRProcessor class.

C#

//Initialize the OCR processor by providing the path of tesseract binaries.
using (OCRProcessor processor = new OCRProcessor(@"TesseractBinaries/"))
{
    //Load an existing PDF document.
    PdfLoadedDocument loadedDocument = new PdfLoadedDocument("Input.pdf");
    //Set the tesseract version 
    processor.Settings.TesseractVersion = TesseractVersion.Version4_0;
    //Set OCR language to process.
    processor.Settings.Language = Languages.English;
    //Process OCR by providing the PDF document and Tesseract data.
    processor.PerformOCR(loadedDocument, @"Tessdata/");  
    //Save the OCR processed PDF document in the disk.
    loadedDocument.Save("OCR.pdf");
    loadedDocument.Close(true);
}

By executing the program, you will get a PDF document as follows.

A complete working sample can be downloaded from GitHub.