C# Barcode Reader How-Tos
PM > Install-Package OnBarcode.Barcode.Reader
C#: How to Start
Read multi-barcodes
Scan image specified regions
Async & multi-thread scanning
Process Barcode Text
Unicode text
Structured Append data
GS1 data elements
Setup .NET Projects
C# Class (.NET Core)
ASP.NET Core
ASP.NET Core MVC
ASP.NET Framework
WinForms (.NET Core)
WPF (.NET Core)
2D Barcode in C#
Data Matrix
PDF417
QR Code
Linear Barcode in C#
Code 39
Code 128
EAN-13
GS1-128
UPC-A

How to read, scan QR Code in C# ASP.NET, MVC web app?

Online tutorial for reading & scanning QR Code barcode images in C# ASP.NET, MVC, WinForms, WPF application

How to read, scan, decode QR Code images in C#.NET class, ASP.NET Web & Windows applications

In this C# tutorial page, you will learn how to scan, read QR Code barcode data from images in C# ASP.NET web app and Windows application.

Scan standard QR Code and GS1 QR Code
Easy to read text with various encoding from QR Code image
Read multiple raster image formats, TIFF, bitmap, jpeg, gif, png.
Scan the whole image area or partial of it.
Extract QR Code data value with barcode location information
Build-in API to easily parse ASCII text, Unicode, Binary data, and GS1 data elements
Quick to build QR Code scanning feature in ASP.NET Core, MVC, ASP.NET Framework, WinForms, WPF web and desktop applications
Support .NET 9, 8, 7, 6, 5, .NET Core 3.1, 2.1, .NET Framework 4.x, 3.x, 2.x

How to read, scan QR Code image in C# application

Download .NET QR Code Reader Library
Install C# library to scan barcode images in .NET apps
Step by Step Tutorial

Scan QR Code barcode in C# class, Console applications
Read QR Code barcode in C# ASP.NET Core web app
Read, decode QR Code images in Visual Studio C# windows application
Easy and simple to integrate QR Code reader component (single dll file) into your C# project
Support .NET 9, 8, 7, 6, 5, .NET Core 3.1, 2.1, .NET Framework 4.x, 3.x, 2.x
Scanning, decoding QR Code from multiple image formats, like BMP, GIF, JPEG, PNG, TIFF formats
Scanning, reading QR Code from multi-page TIFF documents

Quick to Read QR Code using C#

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You can quickly scan qrcodes from an image file in your C# program using C# barcode reader library.

Call method BarcodeScanner.Scan() with QR Code image file path, and scanned barcode format BarcodeType.QRCode, you will get all QR Codes data messages inside the image file

            string[] datas = BarcodeScanner.Scan("qrcode-sample.png", BarcodeType.QRCode);

You can also use method BarcodeScanner.ScanInDetails() to scan and read all information about QR Codes inside the image. View details here How to scan, read QR Code location information using C#?

Scan and read all QR Code informations from an image file using C#

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Call method BarcodeScanner.ScanInDetails() with the same input parameters, you will get all scanned QR Codes with detailed information in BarcodeDetail objects, such as scanned QR Code region.

BarcodeDetail[] datasInDetail = BarcodeScanner.ScanInDetails("qrcode-sample.png", BarcodeType.QRCode);

Here are some information about BarcodeDetail

Rotation: get the scanned QR Code rotation angle
X1, Y1, X2, Y2, X3, Y3, X4, Y4: 4 coordinate locations on the scanned image to cover the scanned QR Code symbol
IsGS1Compitable: If true, the scanned QR Code is a GS1 compatible QR Code. You need read the GS1 data message from it.
IsStructuredAppend: If true, the scanned QR Code symbol is part of the Structured Append QR Code symbols
GetDataBytes(): Get the QR Code data in byte array.
GetMessage(): Get the QR Code data in specified encoding format.

For more information about class BarcodeDetail go here: About class BarcodeDetail in C#

Process scanned QR Code data message using C#

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QR Code supports encoding lots of character sets and some industry standard data formats. To help process these complex data message, barcode reader library develops multiple methods to handle them.

Here you will learn how to process the following character sets or data message from scanned QR Code in C#

ASCII text. Including printing and non-printing chars.
Unicode text
Binary data
GS1 data elements

ASCII text characters

ASCII text include 128 characters. The first 32 characters and the last character are non-printing ones, such as character 'carriage return'.

The following C# source code shows how to scan QR Code and parse the scanned ASCII characters using C#.

Use method BarcodeScanner.Scan() to scan the image containing QR Code symbols.
Parse the scanned QR Code data and replace non-printing char 'carriage return' in the example with visible label '[CR]'

            String[] result = BarcodeScanner.Scan("C://Input//qrcode-ascii-sample.png", BarcodeType.QRCode);

            if (result.Length > 0)
            {
                foreach (String msg in result)
                {
                    Debug.WriteLine("QR Code Raw Message: '" + msg + "'");
                    String tmp = msg.Replace("\r", "[CR]");
                    Debug.WriteLine("QR Code ASCII Text: '" + tmp + "'");
                }
            }
            else
            {
                Debug.WriteLine("No QR Code Scanned!");
            }

Unicode text

QR Code supports Unicode text encoding. To encode Unicode characters into QR Code, the barcode software usually will convert Unicode text to binary data, and create QR Code with binary data using QR Code binary data mode.

To decode QR Code with Unicode text properly, you need use the same encoding as the QR Code generator. The most common encoding is using UTF8 encoding.

The C# code below explains how to read QR Code and decode Unicode text using UTF8 (System.Text.Encoding.UTF8) encoding in C# application.

            BarcodeDetail[] datas = BarcodeScanner.ScanInDetails(
                "C://Input//qrcode-unicode.png", BarcodeType.QRCode);
            
            for (int j = 0; j < datas.Length; j++)
            {
                string textMsgDecoded = System.Text.Encoding.UTF8.GetString(
                    datas[j].GetDataBytes());

                Console.WriteLine("Unicode text: " + textMsgDecoded);
            }

GS1 data message

The GS1 System uses QR Code as one of its data carrier. The GS1 data message encoded in QR Code usually includes a list of AI (Application Identifier) Code and AI data pair, and some control characters, such as Function 1 Symbol Character (FNC1).

The OnBarcode Barcode Reader library will help you easily scan GS1 QR Code and parse GS1 data message without knowing any GS1 control characters. You can easily get the list of GS1 data elements.

    BarcodeDetail[] result = BarcodeScanner.ScanInDetails("C://Input//qrcode-gs1-data.png", BarcodeType.QRCode);

    foreach (BarcodeDetail b in result)
    {
        //  Indicate if the QR Code is conform to GS1 system.
        if (b.IsGS1Compitable)
        {
            //  Get message in string format.
            //  Eg. "(415)5412345678908(3911)710125"
            String msg = b.GetMessage();
            Console.WriteLine("Raw Data: '{0}'", b.Data);
            Console.WriteLine("Text Message: {0}", msg);
            //  Retrieve each AI and its data from the message.
            //  Eg.
            //  AI:   415
            //  Data: 5412345678908
            //  AI:   3911
            //  Data: 710125
            String[] vals = msg.Split(new char[] { '(', ')' }, StringSplitOptions.RemoveEmptyEntries);
            for (int i = 0; i < vals.Length; i += 2)
            {
                Console.WriteLine("AI:    {0}", vals[i]);
                Console.WriteLine("Data:  {0}", vals[i + 1]);
            }
        }
    }

Advanced QR Code Image Scanning Features using C#

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OnBarcode Barcode Reader library provides several methods to improve the QR Code scanning speed.

Quick to scan a single QR Code. If this feature is enabled, once the barcode library scan and detect a QR Code on the fil, it will stop run the remaining job.
Scan QR Code and other barcode format at once
Scan QR Codes from specified regions in the image file

Scan a single QR Code

If this feature is enabled, once the barcode library scan and detect a QR Code on the fil, it will stop run the remaining job.

This feature will really improve the reading speed, if the scanning file contains only one QR Code symbol.

string[] barcodes = BarcodeScanner.ScanSingleBarcode("qrcode-single-barcode.png", BarcodeType.QRCode);

Scan multiple QR Codes

You can easily scan QR Code and other barcode formats (such as Code 128, EAN/UPC) from an image file at once. Or you can scanned all barcode reader library supported barcode formats (using property BarcodeType.All) from a file.

BarcodeDetail[] datas = BarcodeScanner.ScanInDetails("qrcode-multiple-formats.png",
    new List<BarcodeType> { BarcodeType.QRCode, BarcodeType.Code128 });

BarcodeDetail[] datasInDetail = BarcodeScanner.ScanInDetails("qrcode-all-formats.png", BarcodeType.All);

Scan image regions to read QR Codes

To improve the reading speed and reduce the reading error, you can define regions inside the image file. The barcode reader library will scan the QR Code from the specified regions, and it will help to improve the QR Code and other barcodes reading performance.

List<SRegion> regions = new List<SRegion>();
regions.Add(new SRegion(0, 0, 50, 60));
regions.Add(new SRegion(100, 100, 50, 60));

string[] barcodes = BarcodeScanner.ScanRegions("qrcode-barcodes.png", BarcodeType.QRCode, regions);

List<SRegion> regions = new List<SRegion>();
regions.Add(new SRegion(0, 0, 50, 60));
regions.Add(new SRegion(100, 100, 50, 60));

string[] barcodes = BarcodeScanner.ScanSingleBarcodeRegions("qrcode-barcodes.png", BarcodeType.QRCode, regions);

Common Asked Questions

How to read QR Code on desktop?

You can use barcode scanner software installed on computer or barcode scanner device to read and extract QR Code from image. OnBarcode C# QR Code Reader library supports building Windows application with QR Code scanning and reading functions with few lines of C# source codes.

How to read a QR code that's on your screen?

To read a QR Code on your screen, try the following steps

Take and save the screenshot of the QR Code image on the computer
Use QR Code scanner software to read the QR Code from the image

C# QRCode Reader library supports C# developers quickly to build a Windows (WinForms, WPF, or Console) application with QR Code decoder features integrated.

How do I scan a QR code with my phone?

You can download and install QR Code Scanner app on the iPhone or Android phones. OnBarcode C# QR Code Scanner library supports building Xamarin application for iOS and Adroid with QR Code reading functions.

How do you scan a QR code from an image?

Online QR Code decoder, QR Code Scanner software allow you to scan and extract a QR Code from an images. Using OnBarcode QR Code Reader C# SDK, you can quickly build online QR Code scanner based on ASP.NET Core, MVC web app, or Windows QR Code Scanner software using WinForms or WPF framework using C#.

Is there a scanner or reader for QR codes?

You can use iPhone and Android phone build-in QR Code Scanner app to read the QR Codes. If you are C#.NET developer, you can easily build app for iOS and Android with QR Code Reader embed using C# Barcode Reader library with Xamarin.

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