Perform OCR in Linux

16 Jun 20263 minutes to read

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

Pre-requisites

The following Linux dependencies should be installed where the conversion takes place.

BASH

sudo apt-get update
sudo apt-get install libgdiplus
sudo apt-get install libc6-dev
sudo apt-get install libleptonica-dev libjpeg62
ln -s /usr/lib/x86_64-linux-gnu/libtiff.so.6 /usr/lib/x86_64-linux-gnu/libtiff.so.5
ln -s /lib/x86_64-linux-gnu/libdl.so.2 /usr/lib/x86_64-linux-gnu/libdl.so

Steps to convert HTML to PDF in .NET Core application on Linux

Step 1: Execute the following command in the Linux terminal to create a new .NET Core Console application.

BASH

dotnet new console

OCR Linux Step1

Step 2: Install the Syncfusion.PDF.OCR.Net.Core NuGet package as a reference to your .NET Core application NuGet.org.

BASH

dotnet add package Syncfusion.PDF.OCR.Net.Core -v xx.x.x.xx -s https://www.nuget.org/

OCR Linux Step2

Step 3: Include the following namespaces in Program.cs file.

C#
using Syncfusion.OCRProcessor;
using Syncfusion.Pdf;
using Syncfusion.Pdf.Parsing;

NOTE

Beginning from version 21.1.x, the default configuration includes the addition of the TesseractBinaries and Tesseract language data folder paths, eliminating the requirement to explicitly provide these paths.

Step 4: Add code sample to perform OCR on entire PDF document using PerformOCR method of the OCRProcessor class.

C#
string docPath = ("input.pdf");

//Initialize the OCR processor
using (OCRProcessor processor = new OCRProcessor())
{
    //Load the PDF document 
    FileStream stream = new FileStream(docPath, FileMode.Open, FileAccess.Read);
    PdfLoadedDocument lDoc = new PdfLoadedDocument(stream);

    //Language to process the OCR
    processor.Settings.Language = Languages.English;
    //Process OCR by providing loaded PDF document, Data dictionary and language
    processor.PerformOCR(lDoc);

    //Save the OCR processed PDF document in the disk
    MemoryStream streamData = new MemoryStream();
    lDoc.Save(streamData);
    File.WriteAllBytes("Output.pdf", streamData.ToArray());
    lDoc.Close(true);
}