कोड में QR Code पढ़ना और डिकोड करना

QR Code Reading and Decoding in Code

Programmatic QR code reading enables batch processing, automated workflows, and custom scanning applications.

Python: pyzbar

from pyzbar.pyzbar import decode
from PIL import Image

image = Image.open("qrcode.png")
results = decode(image)
for result in results:
    print(result.data.decode("utf-8"))
    print(f"Type: {result.type}, Rect: {result.rect}")

pyzbar wraps the ZBar library — fast and reliable for static image decoding.

Python: OpenCV + pyzbar

For camera-based scanning:

import cv2
from pyzbar.pyzbar import decode

cap = cv2.VideoCapture(0)
while True:
    ret, frame = cap.read()
    codes = decode(frame)
    for code in codes:
        data = code.data.decode("utf-8")
        print(f"Decoded: {data}")

JavaScript: jsQR

Browser-based decoding from Canvas image data:

const imageData = context.getImageData(0, 0, width, height);
const code = jsQR(imageData.data, width, height);
if (code) {
    console.log("Decoded:", code.data);
}

Batch Processing

For processing thousands of QR code images:

import os
from pyzbar.pyzbar import decode
from PIL import Image

results = {}
for filename in os.listdir("qr_images/"):
    if filename.endswith(".png"):
        image = Image.open(f"qr_images/{filename}")
        codes = decode(image)
        results[filename] = [c.data.decode("utf-8") for c in codes]

Error Handling

QR code reading can fail for multiple reasons:

• Image quality too low — increase resolution or preprocessing
• QR code too small in the image — crop or zoom
• Multiple QR codes in one image — most libraries return all found codes
• Damaged or partially obscured — error correction limits apply

Preprocessing for Better Results

• Convert to greyscale before decoding
• Apply adaptive thresholding for uneven lighting
• Increase contrast for faded or low-contrast codes
• Sharpen blurry images before attempting decode

Key Takeaways

• pyzbar (Python) wraps ZBar for fast, reliable static image decoding
• OpenCV + pyzbar enables real-time camera-based scanning in Python
• jsQR provides browser-based decoding from Canvas image data
• Batch processing scripts can decode thousands of QR images
• Image preprocessing (greyscale, contrast, sharpening) improves decode success