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How to Read Specific Documents

by Chaknith Bin

Accurately reading specific documents such as standard text documents, license plates, passports, and photos with a general singular method is very hard. These challenges stem from the diverse formats, layouts, and content of each document type, as well as variations in image quality, distortion, and specialized content. Additionally, achieving contextual understanding and balancing performance and efficiency becomes more complex with a broader scope of document types.

IronOCR introduces specific methods for performing OCR on particular documents such as standard text documents, license plates, passports, and photos to achieve optimal accuracy and performance.

How to Read Specific Documents

  1. Download a C# library to read license plates, passports, and photos
  2. Prepare the image and PDF document for OCR
  3. Set the ReadLicensePlate method to read a license plate
  4. Set the ReadPassport method to retrieve information from a passport
  5. Leverage the ReadPhoto and ReadScreenShot methods to read images that contain hard-to-read text


C# NuGet Library for OCR

Install with NuGet

Install-Package IronOcr
nuget.org/packages/IronOcr/
or
Java PDF JAR

Download DLL

Download DLL

Manually install into your project

About The Package

The methods ReadLicensePlate, ReadPassport, ReadPhoto, and ReadScreenShot are extension methods to the base IronOCR package and require the IronOcr.Extensions.AdvancedScan package to be installed. Currently, this extension is only available on Windows.

The methods work with OCR engine configurations such as blacklist and whitelist. Multiple languages, including Chinese, Japanese, Korean, and LatinAlphabet, are supported in all methods except for the ReadPassport method. Please note that each language requires an additional language package, IronOcr.Languages.

Using advanced scan on .NET Framework requires the project to run on x64 architecture. Navigate to the project configuration and uncheck the "Prefer 32-bit" option to achieve this. Learn more in the following troubleshooting guide: "Advanced Scan on .NET Framework."

Read Document Example

The ReadDocument method is a robust document reading method that specializes in scanned documents or photos of paper documents containing a lot of text. The PageSegmentationMode configuration is very important in reading text documents with different layouts. For example, the SingleBlock and SparseText types could retrieve much information from table layout. This is because SingleBlock assumes that the text stays as a block, whereas SparseText assumes that the text is scattered throughout the document.

:path=/static-assets/ocr/content-code-examples/how-to/read-specific-document-document.cs
using IronOcr;
using System;

// Instantiate OCR engine
var ocr = new IronTesseract();

// Configure OCR engine
ocr.Configuration.PageSegmentationMode = TesseractPageSegmentationMode.SingleBlock;

using var input = new OcrInput();

input.LoadPdf("Five.pdf");

// Perform OCR
OcrResult result = ocr.ReadDocument(input);

Console.WriteLine(result.Text);
Imports IronOcr
Imports System

' Instantiate OCR engine
Private ocr = New IronTesseract()

' Configure OCR engine
ocr.Configuration.PageSegmentationMode = TesseractPageSegmentationMode.SingleBlock

Dim input = New OcrInput()

input.LoadPdf("Five.pdf")

' Perform OCR
Dim result As OcrResult = ocr.ReadDocument(input)

Console.WriteLine(result.Text)
VB   C#

The methods below are extension methods to the base IronOCR package and require the IronOcr.Extensions.AdvancedScan package to be installed. Currently, this extension is only available on Windows.

Read License Plate Example

The ReadLicensePlate method is optimized for reading license plates from photos. The special information returned from this method is the Licenseplate property, which contains the information of the license plate location in the provided document.

:path=/static-assets/ocr/content-code-examples/how-to/read-specific-document-license-plate.cs
using IronOcr;
using IronSoftware.Drawing;
using System;

// Instantiate OCR engine
var ocr = new IronTesseract();

using var inputLicensePlate = new OcrInput();

inputLicensePlate.LoadImage("LicensePlate.jpeg");

// Perform OCR
OcrLicensePlateResult result = ocr.ReadLicensePlate(inputLicensePlate);

// Retrieve license plate coordinates
Rectangle rectangle = result.Licenseplate;

// Retrieve license plate value
string output = result.Text;
Imports IronOcr
Imports IronSoftware.Drawing
Imports System

' Instantiate OCR engine
Private ocr = New IronTesseract()

Private inputLicensePlate = New OcrInput()

inputLicensePlate.LoadImage("LicensePlate.jpeg")

' Perform OCR
Dim result As OcrLicensePlateResult = ocr.ReadLicensePlate(inputLicensePlate)

' Retrieve license plate coordinates
Dim rectangle As Rectangle = result.Licenseplate

' Retrieve license plate value
Dim output As String = result.Text
VB   C#

Read Passport Example

The ReadPassport method is optimized for reading and extracts passport information from passport photos by scanning the machine-readable zone (MRZ) contents. An MRZ is a specially defined zone in official documents such as passports, ID cards, and visas. The MRZ typically contains essential personal information, such as the holder’s name, date of birth, nationality, and document number. Currently, this method only supports English language.

:path=/static-assets/ocr/content-code-examples/how-to/read-specific-document-passport.cs
using IronOcr;
using System;

// Instantiate OCR engine
var ocr = new IronTesseract();

using var inputPassport = new OcrInput();

inputPassport.LoadImage("Passport.jpg");

// Perform OCR
OcrPassportResult result = ocr.ReadPassport(inputPassport);

// Output passport information
Console.WriteLine(result.PassportInfo.GivenNames);
Console.WriteLine(result.PassportInfo.Country);
Console.WriteLine(result.PassportInfo.PassportNumber);
Console.WriteLine(result.PassportInfo.Surname);
Console.WriteLine(result.PassportInfo.DateOfBirth);
Console.WriteLine(result.PassportInfo.DateOfExpiry);
Imports IronOcr
Imports System

' Instantiate OCR engine
Private ocr = New IronTesseract()

Private inputPassport = New OcrInput()

inputPassport.LoadImage("Passport.jpg")

' Perform OCR
Dim result As OcrPassportResult = ocr.ReadPassport(inputPassport)

' Output passport information
Console.WriteLine(result.PassportInfo.GivenNames)
Console.WriteLine(result.PassportInfo.Country)
Console.WriteLine(result.PassportInfo.PassportNumber)
Console.WriteLine(result.PassportInfo.Surname)
Console.WriteLine(result.PassportInfo.DateOfBirth)
Console.WriteLine(result.PassportInfo.DateOfExpiry)
VB   C#

Result

Read Passport

Please make sure that the document only contains the passport image. Any header and footer text could confuse the method and result in an unexpected output.

Read Photo Example

The ReadPhoto method is optimized for reading images that contain hard-to-read text. This method returns the TextRegions property, which contains useful information about the detected text, such as Region, TextInRegion, and FrameNumber.

:path=/static-assets/ocr/content-code-examples/how-to/read-specific-document-photo.cs
using IronOcr;
using IronSoftware.Drawing;

// Instantiate OCR engine
var ocr = new IronTesseract();

using var inputPhoto = new OcrInput();
inputPhoto.LoadImageFrame("photo.tif", 2);

// Perform OCR
OcrPhotoResult result = ocr.ReadPhoto(inputPhoto);

// index number refer to region order in the page
int number = result.TextRegions[0].FrameNumber;
string textinregion = result.TextRegions[0].TextInRegion;
Rectangle region = result.TextRegions[0].Region;
Imports IronOcr
Imports IronSoftware.Drawing

' Instantiate OCR engine
Private ocr = New IronTesseract()

Private inputPhoto = New OcrInput()
inputPhoto.LoadImageFrame("photo.tif", 2)

' Perform OCR
Dim result As OcrPhotoResult = ocr.ReadPhoto(inputPhoto)

' index number refer to region order in the page
Dim number As Integer = result.TextRegions(0).FrameNumber
Dim textinregion As String = result.TextRegions(0).TextInRegion
Dim region As Rectangle = result.TextRegions(0).Region
VB   C#

Read Screenshot Example

The ReadScreenShot method is optimized for reading screenshots that contain hard-to-read text. Similar to the ReadPhoto method, it also returns the TextRegions property.

:path=/static-assets/ocr/content-code-examples/how-to/read-specific-document-screenshot.cs
using IronOcr;
using System;
using System.Linq;

// Instantiate OCR engine
var ocr = new IronTesseract();

using var inputScreenshot = new OcrInput();
inputScreenshot.LoadImage("screenshot.png");

// Perform OCR
OcrPhotoResult result = ocr.ReadScreenShot(inputScreenshot);

// Output screenshoot information
Console.WriteLine(result.Text);
Console.WriteLine(result.TextRegions.First().Region.X);
Console.WriteLine(result.TextRegions.Last().Region.Width);
Console.WriteLine(result.Confidence);
Imports IronOcr
Imports System
Imports System.Linq

' Instantiate OCR engine
Private ocr = New IronTesseract()

Private inputScreenshot = New OcrInput()
inputScreenshot.LoadImage("screenshot.png")

' Perform OCR
Dim result As OcrPhotoResult = ocr.ReadScreenShot(inputScreenshot)

' Output screenshoot information
Console.WriteLine(result.Text)
Console.WriteLine(result.TextRegions.First().Region.X)
Console.WriteLine(result.TextRegions.Last().Region.Width)
Console.WriteLine(result.Confidence)
VB   C#

Chaknith Bin

Software Engineer

Chaknith is the Sherlock Holmes of developers. It first occurred to him he might have a future in software engineering, when he was doing code challenges for fun. His focus is on IronXL and IronBarcode, but he takes pride in helping customers with every product. Chaknith leverages his knowledge from talking directly with customers, to help further improve the products themselves. His anecdotal feedback goes beyond Jira tickets and supports product development, documentation and marketing, to improve customer’s overall experience.When he isn’t in the office, he can be found learning about machine learning, coding and hiking.