Example Detect QR Code

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  Several QR Codes are detected in this image. Correctly decoded ones are highlighted in green and failures in red. Graph of connected position patterns is also shown.

QR Codes are found on many consumer products and often encode information such as a website. BoofCV provides a QR Code detector is designed to be fast on large images, detect small markers in large images, and be rotation invariant. It also provides much more internal information on the QR codes than other popular detectors. It even returns the rejected markers.

Example Code:

• ExampleDetectQrCode.java

Concepts:

• Fiducials
• QR Codes

Relevant Examples/Tutorials:

• Tutorial Fiducials
• Rendering QR Codes

Example Code

/**
 * Shows you how to detect a QR Code inside an image and process the extracted data. Much of the information that
 * is computed while detecting and decoding a QR Code is saved inside the {@link QrCode} class. This can be useful
 * for application developers.
 *
 * @author Peter Abeles
 */
public class ExampleDetectQrCode {
	public static void main(String[] args) {
		BufferedImage input = UtilImageIO.loadImage(UtilIO.pathExample("fiducial/qrcode/image01.jpg"));
		GrayU8 gray = ConvertBufferedImage.convertFrom(input,(GrayU8)null);

		QrCodeDetector<GrayU8> detector = FactoryFiducial.qrcode(null,GrayU8.class);

		detector.process(gray);

		// Get's a list of all the qr codes it could successfully detect and decode
		List<QrCode> detections = detector.getDetections();

		Graphics2D g2 = input.createGraphics();
		int strokeWidth = Math.max(4,input.getWidth()/200); // in large images the line can be too thin
		g2.setColor(Color.GREEN);g2.setStroke(new BasicStroke(strokeWidth));
		for( QrCode qr : detections ) {
			// The message encoded in the marker
			System.out.println("message: "+qr.message);

			// Visualize its location in the image
			VisualizeShapes.drawPolygon(qr.bounds,true,1,g2);
		}

		// List of objects it thinks might be a QR Code but failed for various reasons
		List<QrCode> failures = detector.getFailures();
		g2.setColor(Color.RED);
		for( QrCode qr : failures ) {
			// If the 'cause' is ERROR_CORRECTION or later then it's probably a real QR Code that
			if( qr.failureCause.ordinal() < QrCode.Failure.ERROR_CORRECTION.ordinal() )
				continue;

			VisualizeShapes.drawPolygon(qr.bounds,true,1,g2);
		}

		ShowImages.showWindow(input,"Example QR Codes", true);
	}
}