Step-by-Step Guide To Create QR Scanner Using Raspberry Pi

This guide provides you with a step-by-step guide to creating a QR scanner using Raspberry Pi. The guide contains the installation of Raspbian OS, the Connecting of the camera module to the Pi’s camera port, activation of the camera interface, and updating/upgrading the packages. the QR code can be generated using a website like QR Code Generator.

Required Material

To create a QR code decoder using Raspberry Pi, you will need the following components:

Raspberry Pi board
Raspberry Pi Camera
Internet connection

Install Raspbian Operating System

The first step is to install Raspbian OS on your Raspberry Pi (if you already installed then ignore it). You can download the latest Raspbian OS image from the official Raspberry Pi website and check our previous instructions.

Install OpenCV On Raspberry Pi

Here’s how to install OpenCV on Raspberry Pi first Update and Upgrade: It is recommended to run the following command in a terminal window to update and upgrade the packages on your Raspberry Pi:

sudo apt-get update 
sudo apt-get upgrade

1 2	sudo apt-get update sudo apt-get upgrade

Check out How To Install OpenCV On Raspberry Pi With Command

After completing the installation test if OpenCV is properly installed or not, open the Raspberry Pi terminal and type the following code:

python 
import cv2 
print(cv2.__version__)

python

import cv2

print(cv2.__version__)

If OpenCV is installed perfectly, the version digit should be printed to the terminal.

Install required packages

Install the necessary packages for your Raspberry Pi, please follow the guidelines below:

The below commands will update and upgrade your Raspberry Pi’s packages.

sudo apt-get update
sudo apt-get upgrade
sudo python3 -m pip install -U Pillow
sudo apt-get install libzbar0 libzbar-dev
sudo python3 -m pip install pyzbar
sudo pip3 install PyQt5

sudo apt-get update

sudo apt-get upgrade

sudo python3 -m pip install -U Pillow

sudo apt-get install libzbar0 libzbar-dev

sudo python3 -m pip install pyzbar

sudo pip3 install PyQt5

As well as install the pyzbar and PyQt5 library, which will be used to decode the QR code.

Connect the camera

Connect the camera module to the Raspberry Pi’s camera port.

Enable the camera interface

Run the following command to enable the camera interface

sudo raspi-config

1	sudo raspi-config

To use the Raspberry pi camera, you’ll need to enable the camera interface. Go to “Interfacing options” and then “Camera.”

Test the camera

To test the camera, enter the next command in a terminal window:

This command takes an image from the Raspberry Pi camera and stores it as “test.jpg“. You can see the picture by opening the home directory in the file manager.

Create a Python script: QR Scanner Using Raspberry Pi

Start a new Python script by entering the following command in the terminal window:

nano qrscanner.py

1	nano qrscanner.py

This command opens a text editor. paste the below Python code into the editor:

#visit diyrpojectslab.com for more info..

import sys
import numpy as np

from PyQt5 import QtCore
from PyQt5 import QtWidgets
from PyQt5 import QtGui

from picamera import PiCamera
from pyzbar.pyzbar import decode

class VideoRecorder(QtCore.QObject):
 # To take a snapshot one at a time then emit out in term on numpy ndarray
 image_data = QtCore.pyqtSignal(np.ndarray)
 
 def __init__(self, camera_port=0, parent=None):
  super().__init__(parent)
  self.resolution = (320,240)  
  
  self.camera = PiCamera() 
  self.camera.resolution=self.resolution

  self.timer = QtCore.QBasicTimer()

 def start_recording(self):
  self.timer.start(0, self)

 def timerEvent(self, event):
  if (event.timerId() != self.timer.timerId()):
   return
  
  frame = np.empty((self.resolution[1],self.resolution[0],3),dtype=np.uint8) 
  #capture image

  self.camera.capture(frame,'rgb')
  #emit image out 
  self.image_data.emit(frame)


class DecoderWidget(QtWidgets.QWidget):
 #To display image array and do decoding
 
 def __init__(self,  parent=None):
  super().__init__(parent)
  self.qr_data = []
  self.image = QtGui.QImage()
  self._red = (0, 0, 255)
  self._width = 2
  self._min_size = (30, 30)

 def _decode(self):
  if self.qr_data != [] :
   msg = QtWidgets.QMessageBox()
   msg.setIcon(QtWidgets.QMessageBox.Information)
   msg.setWindowTitle("QR Code Data ")
   msg.setDetailedText(self.qr_data[0].data.decode('utf-8'))
   retval = msg.exec_()
  
  
 
 def image_data_slot(self, image_data: np.ndarray):
  self.qr_data = decode(image_data)
  self.image = self.get_qimage(image_data)
  if self.image.size() != self.size():
   self.setFixedSize(self.image.size())

  self.update()

 def get_qimage(self, image: np.ndarray):
  height, width, colors = image.shape
  bytesPerLine = 3 * width
  QImage = QtGui.QImage
  image = QImage(image.data, width, height, bytesPerLine, QImage.Format_RGB888)
  image = image.rgbSwapped()
  return image

 def paintEvent(self, event):
  painter = QtGui.QPainter(self)
  painter.drawImage(0, 0, self.image)
  self.image = QtGui.QImage()
  
  if self.qr_data != [] :
   col = QtGui.QColor(200, 0, 0)
   col.setNamedColor('#d4d4d4')
   painter.setPen(col)
  
   #painter.setBrush(QtGui.QColor(200, 0, 0))
   rect = self.qr_data[0].rect
   painter.drawRect(rect.left, rect.top, rect.width, rect.height)
  
  

class MainWidget(QtWidgets.QWidget):
 def __init__(self,  parent=None):
  super().__init__(parent)
  self.decoder_widget = DecoderWidget()

  self.recorder = VideoRecorder()
  
  image_data_slot = self.decoder_widget.image_data_slot
  
  self.recorder.image_data.connect(image_data_slot)
  
  layout = QtWidgets.QVBoxLayout()

  layout.addWidget(self.decoder_widget)
  self.run_button = QtWidgets.QPushButton('Decode')
  layout.addWidget(self.run_button)

  self.run_button.clicked.connect(self.decoder_widget._decode)
  self.setLayout(layout)
  self.recorder.start_recording()
  
def main():
 app = QtWidgets.QApplication(sys.argv)

 main_window = QtWidgets.QMainWindow()
 main_widget = MainWidget()
 main_window.setCentralWidget(main_widget)
 main_window.show()
 sys.exit(app.exec_())

if __name__ == '__main__':
    main()

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#visit diyrpojectslab.com for more info..

import sys

import numpy as np

from PyQt5 import QtCore

from PyQt5 import QtWidgets

from PyQt5 import QtGui

from picamera import PiCamera

from pyzbar.pyzbar import decode

class VideoRecorder(QtCore.QObject):

# To take a snapshot one at a time then emit out in term on numpy ndarray

image_data = QtCore.pyqtSignal(np.ndarray)

def __init__(self, camera_port=0, parent=None):

super().__init__(parent)

self.resolution = (320,240)

self.camera = PiCamera()

self.camera.resolution=self.resolution

self.timer = QtCore.QBasicTimer()

def start_recording(self):

self.timer.start(0, self)

def timerEvent(self, event):

if (event.timerId() != self.timer.timerId()):

return

frame = np.empty((self.resolution[1],self.resolution[0],3),dtype=np.uint8)

#capture image

self.camera.capture(frame,'rgb')

#emit image out

self.image_data.emit(frame)

class DecoderWidget(QtWidgets.QWidget):

#To display image array and do decoding

def __init__(self, parent=None):

super().__init__(parent)

self.qr_data = []

self.image = QtGui.QImage()

self._red = (0, 0, 255)

self._width = 2

self._min_size = (30, 30)

def _decode(self):

if self.qr_data != [] :

msg = QtWidgets.QMessageBox()

msg.setIcon(QtWidgets.QMessageBox.Information)

msg.setWindowTitle("QR Code Data ")

msg.setDetailedText(self.qr_data[0].data.decode('utf-8'))

retval = msg.exec_()

def image_data_slot(self, image_data: np.ndarray):

self.qr_data = decode(image_data)

self.image = self.get_qimage(image_data)

if self.image.size() != self.size():

self.setFixedSize(self.image.size())

self.update()

def get_qimage(self, image: np.ndarray):

height, width, colors = image.shape

bytesPerLine = 3 * width

QImage = QtGui.QImage

image = QImage(image.data, width, height, bytesPerLine, QImage.Format_RGB888)

image = image.rgbSwapped()

return image

def paintEvent(self, event):

painter = QtGui.QPainter(self)

painter.drawImage(0, 0, self.image)

self.image = QtGui.QImage()

if self.qr_data != [] :

col = QtGui.QColor(200, 0, 0)

col.setNamedColor('#d4d4d4')

painter.setPen(col)

#painter.setBrush(QtGui.QColor(200, 0, 0))

rect = self.qr_data[0].rect

painter.drawRect(rect.left, rect.top, rect.width, rect.height)

class MainWidget(QtWidgets.QWidget):

def __init__(self, parent=None):

super().__init__(parent)

self.decoder_widget = DecoderWidget()

self.recorder = VideoRecorder()

image_data_slot = self.decoder_widget.image_data_slot

self.recorder.image_data.connect(image_data_slot)

layout = QtWidgets.QVBoxLayout()

layout.addWidget(self.decoder_widget)

self.run_button = QtWidgets.QPushButton('Decode')

layout.addWidget(self.run_button)

self.run_button.clicked.connect(self.decoder_widget._decode)

self.setLayout(layout)

self.recorder.start_recording()

def main():

app = QtWidgets.QApplication(sys.argv)

main_window = QtWidgets.QMainWindow()

main_widget = MainWidget()

main_window.setCentralWidget(main_widget)

main_window.show()

sys.exit(app.exec_())

if __name__ == '__main__':

main()

Save the file “ctrl +s” and exit the text editor by pressing “Ctrl + X“, then “Y“, and then “Enter”.

This code will operate the camera to capture video frames, detect and scan any QR codes in the framing, and show the decoded data in the terminal window.

Working

Finally, run the code by entering the following command.

python qrscanner.py

1	python qrscanner.py

it’s Working fine

Create QR code

There are many online tools that you can use to generate a QR code quickly and easily.

Choose a QR code generator website, such as https://www.qr-code-generator.com/ or https://www.the-qrcode-generator.com/.

Select the “Text” option from the list.

Start entering the text in the input box right now. You can insert any text you like, such as a URL, a message, or any other information you want to Scan.