QR Code detection

Regular barcodes:

- Linear ones or one-dimensional barcodes are series of lines of varying widths.

- Stores limited amount of information

- They can be only read by specialized barcode scanners

- Must be scanned from left to right

QR code:

- Two-dimensional bar code

- Grid of black and white squares

- Can be read by almost any smartphone or other device with a camera

- Can be read from any direction

Black and white squares in QR code:

- They represent binary data

- Each square is either black or white

- The position and arrangement of the squares are determined by a complex algorithm that ensures that the code can be read accurately even if the QR code is partially obscured or distorted.

Alignment patterns:

- These are the squares in the corners of a QR code

- Used to determine the orientation of the code

- Also used to correct any distortion that may have occurred

Applications of QR code:

- Mobile phone applications

- Websites

- Medical industry

Why QR code:

It contains error checking element that allows the code to be read even if it is damaged.

ways to read QR code:

• OpenCV (we used)
• hashlib

Steps for QR code detection:

1. install and load packages

!pip install opencv-python

import glob

import cv2

import pandas as pd

import pathlib

2. open and read QR code

read_qr_code() to read the QR code

cv2.imread() function to read the image

cv2.QRCodeDetector() class

detectAndDecode() function to extract data from the QR code

Working on bigdata:

- Create Pandas dataframe with two columns: filename, qr

- Load jpg files into directory and store in files

- Open, read, detect QR codes in thousands of images and store the outputs

File formats:

png, jpeg, pdf

References:

https://practicaldatascience.co.uk/data-science/how-to-read-qr-codes-in-python-using-opencv

How to create a QR code using Python

Generate QR code:

Libraries: pillow, qrcode

Key points:

• Python QR Code image generator: qrcode
• Generate QR code image from the command line
• Generate QR code image with Python code
• QR code version of the generated image: version
• Error correction level: error_correction
• Cell size: box_size
• Margin width: border
• Color: fill_color, back_color
• Embed the QR code into the image
• Embed the image into the QR code

References:

Generate QR code image with Python, Pillow, qrcode | note.nkmk.me

Detect and read QR codes with OpenCV

Steps:

• cv2.QRCodeDetector
• Detect and read QR codes from an image
• Detect and read QR codes from camera video

References:

https://note.nkmk.me/en/python-opencv-qrcode/#:~:text=The%20cv2.,detect%20and%20read%20QR%20codes.&text=In%20version%204.3%20%2C%20detectAndDecodeMulti(),they%20are%20not%20mentioned%20here.

QR code validation:

1. Read QR Code from Image — Inverted Colour, Perspective Distortion, and Grayscale

https://www.dynamsoft.com/codepool/optimize-qr-recognition-performance.html

2. Locate QR code in large image to improve decoding performance

https://stackoverflow.com/questions/63195577/how-to-locate-qr-code-in-large-image-to-improve-decoding-performance

3. Read blurry barcode in python with pyzbar

https://stackoverflow.com/questions/64111254/read-blurry-barcode-in-python-with-pyzbar

4. Expire time of QR code

https://stackoverflow.com/questions/47598533/the-expire-time-of-qr-code

Furthermore:

12 Reasons Why Your QR Code is Not Working