vpDetectorQRCode Class Reference

#include <visp3/detection/vpDetectorQRCode.h>

Inheritance diagram for vpDetectorQRCode:

Public Member Functions
	vpDetectorQRCode ()
virtual	~vpDetectorQRCode ()
bool	detect (const vpImage< unsigned char > &I)
Inherited functionalities from vpDetectorBase
vpRect	getBBox (size_t i) const
vpImagePoint	getCog (size_t i) const
std::vector< std::string > &	getMessage ()
std::string &	getMessage (size_t i)
size_t	getNbObjects () const
std::vector< std::vector< vpImagePoint > > &	getPolygon ()
std::vector< vpImagePoint > &	getPolygon (size_t i)

Protected Attributes
zbar::ImageScanner	m_scanner
std::vector< std::vector< vpImagePoint > >	m_polygon
std::vector< std::string >	m_message
size_t	m_nb_objects

Detailed Description

Base class for bar code detector. This class is a wrapper over libzbar available from http://zbar.sourceforge.net. Installation instructions are provided here https://visp.inria.fr/3rd_zbar.

The detect() function allows to detect multiple QR codes in an image. Once detected, for each QR code it is possible to retrieve the location of the corners using getPolygon(), the encoded message using getMessage(), the bounding box using getBBox() and the center of gravity using getCog().

The following sample code shows how to use this class to detect QR codes in an image.

#include <visp3/detection/vpDetectorQRCode.h>
#include <visp3/io/vpImageIo.h>

int main()
{
#ifdef VISP_HAVE_ZBAR
  vpImage<unsigned char> I;
  vpImageIo::read(I, "bar-code.pgm");

  vpDetectorQRCode detector;

  bool status = detector.detect(I);
  if (status) {
    for(size_t i=0; i < detector.getNbObjects(); i++) {
      std::cout << "Bar code " << i << ":" << std::endl;
      std::vector<vpImagePoint> p = detector.getPolygon(i);
      for(size_t j=0; j < p.size(); j++)
        std::cout << "  Point " << j << ": " << p[j] << std::endl;
      std::cout << "  Message: \"" << detector.getMessage(i) << "\"" << std::endl;
    }
  }
#endif
}

The previous example may produce results like:

Bar code 0:
  Point 0: 48, 212
  Point 1: 57, 84
  Point 2: 188, 92
  Point 3: 183, 220
  Message: "qrcode 2"
Bar code 1:
  Point 0: 26, 550
  Point 1: 35, 409
  Point 2: 174, 414
  Point 3: 167, 555
  Message: "qrcode 1"

Other examples are also provided in tutorial-barcode-detector.cpp and tutorial-barcode-detector-live.cpp

Examples:

tutorial-barcode-detector-live.cpp, tutorial-barcode-detector.cpp, and tutorial-pose-from-qrcode-image.cpp.

Definition at line 114 of file vpDetectorQRCode.h.

Constructor & Destructor Documentation

vpDetectorQRCode()

vpDetectorQRCode::vpDetectorQRCode

(

)

Default constructor.

Definition at line 48 of file vpDetectorQRCode.cpp.

References m_scanner.

~vpDetectorQRCode()

virtual vpDetectorQRCode::~vpDetectorQRCode ( )

inlinevirtual

Definition at line 121 of file vpDetectorQRCode.h.

References vpDetectorBase::detect().

Member Function Documentation

detect()

bool vpDetectorQRCode::detect ( const vpImage< unsigned char > &  I )

virtual

Detect QR codes in the image. Return true if a code is detected, false otherwise.

Parameters

I	: Input image.

Implements vpDetectorBase.

Examples:

tutorial-pose-from-qrcode-image.cpp.

Definition at line 60 of file vpDetectorQRCode.cpp.

References vpImage< Type >::bitmap, vpImage< Type >::getHeight(), vpImage< Type >::getWidth(), vpDetectorBase::m_message, vpDetectorBase::m_nb_objects, vpDetectorBase::m_polygon, and m_scanner.

getBBox()

vpRect vpDetectorBase::getBBox ( size_t  i ) const

inherited

Return the bounding box of the ith object.

Examples:

testAprilTag.cpp, tutorial-apriltag-detector.cpp, tutorial-barcode-detector-live.cpp, tutorial-barcode-detector.cpp, tutorial-face-detector-live-threaded.cpp, tutorial-face-detector-live.cpp, and tutorial-face-detector.cpp.

Definition at line 87 of file vpDetectorBase.cpp.

References vpDetectorBase::m_polygon.

getCog()

vpImagePoint vpDetectorBase::getCog ( size_t  i ) const

inherited

Return the center of gravity location of the ith object.

Definition at line 74 of file vpDetectorBase.cpp.

References vpDetectorBase::m_polygon.

getMessage() [1/2]

std::vector<std::string>& vpDetectorBase::getMessage ( void  )

inlineinherited

Returns the contained message of the ith object if there is one.

Examples:

testAprilTag.cpp, tutorial-apriltag-detector.cpp, tutorial-barcode-detector-live.cpp, tutorial-barcode-detector.cpp, tutorial-face-detector-live.cpp, and tutorial-face-detector.cpp.

Definition at line 107 of file vpDetectorBase.h.

getMessage() [2/2]

std::string & vpDetectorBase::getMessage ( size_t  i )

inherited

Returns the contained message of the ith object if there is one.

Definition at line 62 of file vpDetectorBase.cpp.

References vpException::badValue, vpDetectorBase::m_message, and vpDetectorBase::m_polygon.

getNbObjects()

size_t vpDetectorBase::getNbObjects ( ) const

inlineinherited

Return the number of objects that are detected.

Examples:

testAprilTag.cpp, tutorial-apriltag-detector-live.cpp, tutorial-apriltag-detector.cpp, tutorial-barcode-detector-live.cpp, tutorial-barcode-detector.cpp, tutorial-face-detector-live.cpp, tutorial-face-detector.cpp, and tutorial-pose-from-qrcode-image.cpp.

Definition at line 117 of file vpDetectorBase.h.

getPolygon() [1/2]

std::vector<std::vector<vpImagePoint> >& vpDetectorBase::getPolygon ( )

inlineinherited

Returns object container box as a vector of points.

Examples:

testAprilTag.cpp, tutorial-apriltag-detector.cpp, tutorial-barcode-detector-live.cpp, tutorial-barcode-detector.cpp, and tutorial-pose-from-qrcode-image.cpp.

Definition at line 122 of file vpDetectorBase.h.

getPolygon() [2/2]

std::vector< vpImagePoint > & vpDetectorBase::getPolygon ( size_t  i )

inherited

Returns ith object container box as a vector of points.

Definition at line 50 of file vpDetectorBase.cpp.

References vpException::badValue, and vpDetectorBase::m_polygon.

Member Data Documentation

m_message

std::vector<std::string> vpDetectorBase::m_message

protectedinherited

Message attached to each object.

Definition at line 71 of file vpDetectorBase.h.

Referenced by vpDetectorFace::detect(), vpDetectorDataMatrixCode::detect(), detect(), vpDetectorAprilTag::detect(), and vpDetectorBase::getMessage().

m_nb_objects

size_t vpDetectorBase::m_nb_objects

protectedinherited

Number of detected objects.

Definition at line 72 of file vpDetectorBase.h.

Referenced by vpDetectorFace::detect(), vpDetectorDataMatrixCode::detect(), detect(), and vpDetectorAprilTag::detect().

m_polygon

std::vector<std::vector<vpImagePoint> > vpDetectorBase::m_polygon

protectedinherited

For each object, defines the polygon that contains the object.

Definition at line 67 of file vpDetectorBase.h.

Referenced by vpDetectorFace::detect(), vpDetectorDataMatrixCode::detect(), detect(), vpDetectorAprilTag::detect(), vpDetectorBase::getBBox(), vpDetectorBase::getCog(), vpDetectorBase::getMessage(), and vpDetectorBase::getPolygon().

m_scanner

zbar::ImageScanner vpDetectorQRCode::m_scanner

protected

QR code detector.

Definition at line 117 of file vpDetectorQRCode.h.

Referenced by detect(), and vpDetectorQRCode().