ByteScout PDF Extractor SDK - ASP.NET C# - OCR (Optical Character Recognition) in PDF - ByteScout

ByteScout PDF Extractor SDK – ASP.NET C# – OCR (Optical Character Recognition) in PDF

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OCR (optical character recognition) in PDF in ASP.NET C# with ByteScout PDF Extractor SDK

How to code OCR (optical character recognition) in PDF in ASP.NET C#: How-To tutorial

ByteScout tutorials explain the material for programmers who use ASP.NET C#. OCR (optical character recognition) in PDF in ASP.NET C# can be implemented with ByteScout PDF Extractor SDK. ByteScout PDF Extractor SDK is the Software Development Kit (SDK) that is designed to help developers with data extraction from unstructured documents like pdf, tiff, scans, images, scanned and electronic forms. The library is powered by OCR, computer vision and AI to provide unique functionality like table detection, automatic table structure extraction, data restoration, data restructuring and reconstruction. Supports PDF, TIFF, PNG, JPG images as input and can output CSV, XML, JSON formatted data. Includes full set of utilities like pdf splitter, pdf merger, searchable pdf maker.

You will save a lot of time on writing and testing code as you may just take the code below and use it in your application. In order to implement this functionality, you should copy and paste code below into your app using code editor. Then compile and run your application. You can use these ASP.NET C# sample examples in one or many applications.

ByteScout PDF Extractor SDK is available as free trial. You may get it from our website along with all other source code samples for ASP.NET C# applications.

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Default.aspx
      
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="OpticalCharacterRecognition._Default" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server"> <title>Untitled Page</title> </head> <body> <form id="form1" runat="server"> <div> </div> </form> </body> </html>

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Default.aspx.cs
      
using System; using Bytescout.PDFExtractor; // Before running the example, copy missing *.traineddata files from "Redistributable" folder to "ocrdata" project folder. // or download from https://github.com/bytescout/ocrdata // Make sure "Copy to Output Directory" property of each added language file is set to "Copy always". namespace OpticalCharacterRecognition { /* IF YOU SEE TEMPORARY FOLDER ACCESS ERRORS: Temporary folder access is required for web application when you use ByteScout SDK in it. If you are getting errors related to the access to temporary folder like "Access to the path 'C:\Windows\TEMP\... is denied" then you need to add permission for this temporary folder to make ByteScout SDK working on that machine and IIS configuration because ByteScout SDK requires access to temp folder to cache some of its data for more efficient work. SOLUTION: If your IIS Application Pool has "Load User Profile" option enabled the IIS provides access to user's temp folder. Check user's temporary folder If you are running Web Application under an impersonated account or IIS_IUSRS group, IIS may redirect all requests into separate temp folder like "c:\temp\". In this case - check the User or User Group your web application is running under - then add permissions for this User or User Group to read and write into that temp folder (c:\temp or c:\windows\temp\ folder) - restart your web application and try again */ public partial class _Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { String inputFile = Server.MapPath(@".\bin\sample_ocr.pdf"); // Location of language files String ocrLanguageDataFolder = Server.MapPath(@".\bin\ocrdata"); // Create Bytescout.PDFExtractor.TextExtractor instance using (TextExtractor extractor = new TextExtractor()) { extractor.RegistrationName = "demo"; extractor.RegistrationKey = "demo"; // Enable Optical Character Recognition (OCR) // in .Auto mode (SDK automatically checks if needs to use OCR or not) extractor.OCRMode = OCRMode.Auto; // Set the location of OCR language data files extractor.OCRLanguageDataFolder = ocrLanguageDataFolder; // Set OCR language extractor.OCRLanguage = "eng"; // "eng" for english, "deu" for German, "fra" for French, "spa" for Spanish etc - according to files in "ocrdata" folder // Set PDF document rendering resolution extractor.OCRResolution = 300; // You can also apply various preprocessing filters // to improve the recognition on low-quality scans. // Automatically deskew skewed scans //extractor.OCRImagePreprocessingFilters.AddDeskew(); // Remove vertical or horizontal lines (sometimes helps to avoid OCR engine's page segmentation errors) //extractor.OCRImagePreprocessingFilters.AddVerticalLinesRemover(); //extractor.OCRImagePreprocessingFilters.AddHorizontalLinesRemover(); // Repair broken letters //extractor.OCRImagePreprocessingFilters.AddDilate(); // Remove noise //extractor.OCRImagePreprocessingFilters.AddMedian(); // Apply Gamma Correction //extractor.OCRImagePreprocessingFilters.AddGammaCorrection(); // Add Contrast //extractor.OCRImagePreprocessingFilters.AddContrast(20); // (!) You can use new OCRAnalyser class to find an optimal set of image preprocessing // filters for your specific document. // See "OCR Analyser" example. // Load PDF document extractor.LoadDocumentFromFile(inputFile); // Write extracted text to output stream Response.Clear(); Response.ContentType = "text/html"; Response.Write("<pre>"); // Write extracted text to output stream Response.Write(extractor.GetText()); Response.Write("</pre>"); Response.End(); } } } }

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Default.aspx.designer.cs
      
//------------------------------------------------------------------------------ // <auto-generated> // This code was generated by a tool. // Runtime Version:2.0.50727.4952 // // Changes to this file may cause incorrect behavior and will be lost if // the code is regenerated. // </auto-generated> //------------------------------------------------------------------------------ namespace ExtractAllText { /// <summary> /// _Default class. /// </summary> /// <remarks> /// Auto-generated class. /// </remarks> public partial class _Default { /// <summary> /// form1 control. /// </summary> /// <remarks> /// Auto-generated field. /// To modify move field declaration from designer file to code-behind file. /// </remarks> protected global::System.Web.UI.HtmlControls.HtmlForm form1; } }

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Web.config
      
<?xml version="1.0"?> <configuration> <appSettings/> <connectionStrings/> <system.web> <!-- Set compilation debug="true" to insert debugging symbols into the compiled page. Because this affects performance, set this value to true only during development. --> <compilation debug="true" /> <!-- The <authentication> section enables configuration of the security authentication mode used by ASP.NET to identify an incoming user. --> <authentication mode="Windows" /> <!-- The <customErrors> section enables configuration of what to do if/when an unhandled error occurs during the execution of a request. Specifically, it enables developers to configure html error pages to be displayed in place of a error stack trace. <customErrors mode="RemoteOnly" defaultRedirect="GenericErrorPage.htm"> <error statusCode="403" redirect="NoAccess.htm" /> <error statusCode="404" redirect="FileNotFound.htm" /> </customErrors> --> </system.web> </configuration>

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