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How to read Barcodes from PDF Documents

ByHairil Hasyimi Bin Omar

March 19, 2023

Updated  June 1, 2025

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How to Read Barcode From PDF in C#

1. Install the barcode library to process barcode files.
2. Create PdfBarcodeReaderOptions if required.
3. Use the ReadPdf method from BarcodeReader to read barcodes from PDFs.
4. Specify additional barcode reading options using BarcodeReaderOption.
5. Extract barcode values.

Read Barcodes from PDF Documents directly

Apart from IronBarcodes' ability to read barcodes from images, IronBarcode also takes pride in its ability to read barcodes from PDF documents. This saves users from the hassle of converting PDF documents into images before feeding them into IronBarcode for reading. Since PDF documents are more intricate and different from images, a different read method should also be used, and that is the BarcodeReader.ReadPdf() method. This method accepts various types of PDF document input, including:

• byte[] array: PDF document as a byte array.
• IEnumerable<Byte[]>: PDF documents as byte arrays stored in a collection.
• MemoryStream: PDF documents as MemoryStream type.
• IEnumerable<Stream>: PDF documents as a collection of MemoryStream.
• String: PDF document path as a string. If the PDF document is already copied into the project, this would be the name of the PDF document in a string.
• IEnumerable<String>: PDF document path/name strings stored in a collection.

Apart from the types of input mentioned above, BarcodeReader.ReadPdf() also accepts PdfBarcodeReaderOptions for more advanced/improved reading which we will discuss in the next subtopic. Now, let us see the code snippet below that demonstrates the use of the BarcodeReader.ReadPdf() method to read barcodes in PDF documents.

:path=/static-assets/barcode/content-code-examples/how-to/read-barcodes-from-pdf-1.cs

// Import necessary namespaces
using IronBarCode;  // Library for reading barcodes
using System;
using System.Collections.Generic;

// Main code execution

// Create a list to hold the PDF document file paths
List<string> docs = new List<string>
{
    @"pdf_a.pdf",  // Add the first PDF file path
    @"pdf_b.pdf"   // Add the second PDF file path
};

// Read barcodes from the list of PDF documents
// The ReadPdf method can also accept a single PDF document file path as an argument
IEnumerable<BarcodeResult> myBarcode = BarcodeReader.ReadPdf(docs);

// Iterate through each barcode result and output its string representation to the console
foreach (var barcode in myBarcode)
{
    // Output the details of each barcode found in the PDFs to the console
    Console.WriteLine(barcode.ToString());
}

' Import necessary namespaces

Imports IronBarCode ' Library for reading barcodes

Imports System

Imports System.Collections.Generic



' Main code execution



' Create a list to hold the PDF document file paths

Private docs As New List(Of String) From {"pdf_a.pdf", "pdf_b.pdf"}



' Read barcodes from the list of PDF documents

' The ReadPdf method can also accept a single PDF document file path as an argument

Private myBarcode As IEnumerable(Of BarcodeResult) = BarcodeReader.ReadPdf(docs)



' Iterate through each barcode result and output its string representation to the console

For Each barcode In myBarcode

	' Output the details of each barcode found in the PDFs to the console

	Console.WriteLine(barcode.ToString())

Next barcode

From the code snippet above, we can see that to read barcodes using IronBarcode, we can simply add the file path string of the PDF document into the BarcodeReader.ReadPdf() method to read the barcode value and store the result in a variable. If you wish to print the values of all the barcodes found in the PDF document onto the console, just use a foreach loop to iterate and print every element found in the variable by calling the ToString() method on them. On top of that, the code snippet above also demonstrates using a collection of PDF document names as an argument in BarcodeReader.ReadPdf().

But what if the barcodes in the PDF document are unable to be read? What if the performance is slow? This is where advanced PDF barcode reading takes place, in which we manipulate PdfBarcodeReaderOptions to improve reading quality, accuracy, and performance.

Setting PDF Barcode Reader Options

Similar to reading barcodes from images, reading barcodes from PDF documents also allows users to tweak or adjust the properties in the barcode reader called PdfBarcodeReaderOptions. Adjusting the properties in PdfBarcodeReaderOptions will greatly help in reading quality, accuracy, and performance. All the adjustable properties in BarcodeReaderOptions are inherited in PdfBarcodeReaderOptions, with some additional properties for PDF documents. Users can specify the page number or collection of page numbers from the PDF document in which they want the PdfBarcodeReaderOptions to apply when instantiating a new instance of PdfBarcodeReaderOptions. The code snippet below demonstrates:

:path=/static-assets/barcode/content-code-examples/how-to/read-barcodes-from-pdf-2.cs

using IronBarCode;
using System.Collections.Generic;

// Create a list of page numbers where barcodes need to be read within a PDF
List<int> pageNumbers = new List<int> { 1, 2, 3 };

// Initialize PDF Barcode Reader Options with the list of page numbers
PdfBarcodeReaderOptions pdfOptions = new PdfBarcodeReaderOptions(pageNumbers)
{
    // Properties of PDF Barcode reader options can be configured here if needed.
    // Here you might set things like Barcode Encoding or specifying the quality
    // settings for reading the barcodes. Check the IronBarCode documentation for
    // detailed properties you can set.
};

// Note: The above setup assumes that the IronBarCode library is being used to read barcodes
// from a PDF document. The `PdfBarcodeReaderOptions` allows specifying which pages should be
// scanned for barcodes. Adjust the properties in `pdfOptions` according to the requirements
// of the IronBarCode library and your specific use case to enhance barcode reading accuracy
// or performance.

Imports IronBarCode

Imports System.Collections.Generic



' Create a list of page numbers where barcodes need to be read within a PDF

Private pageNumbers As New List(Of Integer) From {1, 2, 3}



' Initialize PDF Barcode Reader Options with the list of page numbers

Private pdfOptions As New PdfBarcodeReaderOptions(pageNumbers)



' Note: The above setup assumes that the IronBarCode library is being used to read barcodes

' from a PDF document. The `PdfBarcodeReaderOptions` allows specifying which pages should be

' scanned for barcodes. Adjust the properties in `pdfOptions` according to the requirements

' of the IronBarCode library and your specific use case to enhance barcode reading accuracy

' or performance.

Now let us discover the additional properties in PdfBarcodeReaderOptions available to manipulate, aside from those available in BarcodeReaderOptions.

DPI

Users can specify the DPI or Dots Per Inch of the barcode image in a PDF document. This will help in reading a low-quality barcode image in a PDF document. This property can be set using an Integer value.

PageNumbers

If users know beforehand the page number that contains the barcode that needs to be read in a PDF document, they can specify it in this property. Doing this will greatly improve the reading performance of IronBarcode, especially for PDF documents that have many pages, since IronBarcode would not need to read all pages or pages that do not have barcodes to be read. This property is 1-based, meaning the first page of the PDF document is 1 instead of 0.

Password

As the name suggests, this property enables users to work with encrypted PDF files that require password input to access the contents of the PDF document. Kindly note however, IronBarcode will not be able to provide the PDF document's password. This property will accept a String input.

Scale

This property enables users to control the scale factor for scaling width and height when converting to an Image. This property accepts an Integer as a value, and the default value for this property is 3.5. Setting this property will help in reading small barcodes present in a PDF document, as scaling up will zoom the PDF document.

Advanced Barcode Reading from PDF Document

Now that we know the properties in PdfBarcodeReaderOptions available for adjustments and tweaks, let us see how to apply them in the project for reading barcodes in a PDF document.

:path=/static-assets/barcode/content-code-examples/how-to/read-barcodes-from-pdf-3.cs

using IronBarCode;
using System;
using System.Collections.Generic;

// Create a list of integer values representing the page numbers from which you want to read barcodes
List<int> pageNumbers = new List<int>() { 1, 2, 3 };

// Instantiate the PdfBarcodeReaderOptions and configure its properties
PdfBarcodeReaderOptions pdfOptions = new PdfBarcodeReaderOptions(pageNumbers)
{
    DPI = 150,  // Set the dots per inch for optimal reading accuracy
    Password = "barcode",  // Set the PDF password, if the document is password-protected
    Scale = 3.5,  // Set the scaling factor for rendering the PDF during barcode reading

    // Properties inherited from BarcodeReaderOptions
    Speed = ReadingSpeed.Detailed,  // Use detailed speed for more thorough reading, albeit slower
    ExpectBarcodeTypes = BarcodeEncoding.Code93,  // Indicate expected barcode type for improved accuracy
    ExpectMultipleBarcodes = true  // Allow detection of multiple barcodes on the same page
};

// Attempt to read the barcodes from the specified PDF file using the configured options
var myBarcodes = BarcodeReader.ReadPdf(@"pdf_a_filepath.pdf", pdfOptions);

// Iterate through all discovered barcodes and print their string representations to the console
foreach (var barcode in myBarcodes)
{
    Console.WriteLine(barcode.ToString());  // Output details for each detected barcode
}

Imports IronBarCode

Imports System

Imports System.Collections.Generic



' Create a list of integer values representing the page numbers from which you want to read barcodes

Private pageNumbers As New List(Of Integer)() From {1, 2, 3}



' Instantiate the PdfBarcodeReaderOptions and configure its properties

Private pdfOptions As New PdfBarcodeReaderOptions(pageNumbers) With {

	.DPI = 150,

	.Password = "barcode",

	.Scale = 3.5,

	.Speed = ReadingSpeed.Detailed,

	.ExpectBarcodeTypes = BarcodeEncoding.Code93,

	.ExpectMultipleBarcodes = True

}



' Attempt to read the barcodes from the specified PDF file using the configured options

Private myBarcodes = BarcodeReader.ReadPdf("pdf_a_filepath.pdf", pdfOptions)



' Iterate through all discovered barcodes and print their string representations to the console

For Each barcode In myBarcodes

	Console.WriteLine(barcode.ToString()) ' Output details for each detected barcode

Next barcode

The code snippet above demonstrates how to implement PdfBarcodeReaderOptions properties in IronBarcode. The PdfBarcodeReaderOptions first needs to be initialized with a variable name before accessing and adjusting the properties. In the code snippet, we can see that the list of page numbers of the PDF document was used as an argument when initializing PdfBarcodeReaderOptions. This specifies the page number that we want the settings of PdfBarcodeReader to apply. Users can also specify the PDF page number in the PdfBarcodeReaderOptions property as PageNumbers.

On the other hand, we can also see that we can use properties from BarcodeReaderOptions such as ExpectMultipleBarcodes and ExpectBarcodeTypes in PdfBarcodeReaderOptions since they are inherited from the original class. This will greatly help in overall reading performance and accuracy. To apply the set properties of PdfBarcodeReaderOptions in the barcode read, input the variable name of the PdfBarcodeReaderOptions class we created as the second argument in the BarcodeReader.ReadPdf() method, with the PDF document to be read file path as the first argument.

Hairil Hasyimi Bin Omar

  Chat with engineering team now

Software Engineer

Like all great engineers, Hairil is an avid learner. He’s refining his knowledge of C#, Python, and Java, using that knowledge to add value to team members across Iron Software. Hairil joined the Iron Software team from Universiti Teknologi MARA in Malaysia, where he graduated with a Bachelor's degree in Chemical and Process Engineering.