QR Code & Barcode Reader

Detect and decode QR codes and barcodes in real-time.

View Source Code

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Overview

Scan QR codes and barcodes using OpenCV’s built-in detectors. Useful for payment systems, inventory management, and ticket scanning.

Key Techniques:

• QRCodeDetector
• BarcodeDetector (OpenCV 4.5.3+)
• Real-time video processing

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How It Works

Frame → Detect → Decode → Display Result
   ↓       ↓        ↓          ↓
[Image]  [Find   [Read     [Show
          corners] data]    decoded text]

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Key OpenCV Functions

# QR Code Detection
qr_detector = cv2.QRCodeDetector()

# Detect and decode single QR
data, points, straight_qr = qr_detector.detectAndDecode(frame)

if data:
    print(f"QR Code: {data}")
    # Draw bounding polygon
    points = points[0].astype(int)
    cv2.polylines(frame, [points], True, (0, 255, 0), 3)

# Detect multiple QR codes
retval, decoded_info, points, _ = qr_detector.detectAndDecodeMulti(frame)

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Barcode Detection (OpenCV 4.5.3+)

# Create barcode detector
barcode_detector = cv2.barcode.BarcodeDetector()

# Detect and decode
retval, decoded_info, decoded_type, points = barcode_detector.detectAndDecode(frame)

if retval:
    for i, data in enumerate(decoded_info):
        print(f"Barcode ({decoded_type[i]}): {data}")

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Supported Formats

Type	Formats
QR Code	Standard QR, Micro QR
1D Barcodes	EAN-13, EAN-8, UPC-A, UPC-E
	Code-39, Code-93, Code-128
	ITF, Codabar

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Tips for Better Detection

1. Good lighting: Avoid shadows and glare
2. Steady camera: Motion blur reduces accuracy
3. Proper distance: Code should fill 30-70% of frame
4. Clean codes: Damaged codes may not scan

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Controls

Key	Action
s	Save screenshot with detection
q	Quit

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Running the Application

python curriculum/applications/07_qr_barcode_reader.py

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Official Documentation

• QRCodeDetector
• BarcodeDetector