Visual Servoing Platform  version 3.2.0
vpDetectorQRCode Class Reference

#include <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
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 113 of file vpDetectorQRCode.h.

Constructor & Destructor Documentation

◆ vpDetectorQRCode()

vpDetectorQRCode::vpDetectorQRCode ( )

Default constructor.

Definition at line 47 of file vpDetectorQRCode.cpp.

◆ ~vpDetectorQRCode()

virtual vpDetectorQRCode::~vpDetectorQRCode ( )
inlinevirtual

Definition at line 120 of file vpDetectorQRCode.h.

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 59 of file vpDetectorQRCode.cpp.

◆ getBBox()

vpRect vpDetectorBase::getBBox ( size_t  i) const
inherited

◆ getCog()

vpImagePoint vpDetectorBase::getCog ( size_t  i) const
inherited

Return the center of gravity location of the ith object.

Examples
mbot-apriltag-2D-half-vs.cpp, and mbot-apriltag-ibvs.cpp.

Definition at line 73 of file vpDetectorBase.cpp.

◆ getMessage() [1/2]

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

◆ 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 61 of file vpDetectorBase.cpp.

◆ getNbObjects()

◆ getPolygon() [1/2]

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

◆ 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 49 of file vpDetectorBase.cpp.

Member Data Documentation

◆ m_message

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

Message attached to each object.

Definition at line 70 of file vpDetectorBase.h.

◆ m_nb_objects

size_t vpDetectorBase::m_nb_objects
protectedinherited

Number of detected objects.

Definition at line 71 of file vpDetectorBase.h.

◆ m_polygon

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

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

Definition at line 66 of file vpDetectorBase.h.

◆ m_scanner

zbar::ImageScanner vpDetectorQRCode::m_scanner
protected

QR code detector.

Definition at line 116 of file vpDetectorQRCode.h.

vpDetectorBase::getPolygon
std::vector< std::vector< vpImagePoint > > & getPolygon()
Definition: vpDetectorBase.h:121
vpImageIo::read
static void read(vpImage< unsigned char > &I, const std::string &filename)
Definition: vpImageIo.cpp:206
vpDetectorBase::getNbObjects
size_t getNbObjects() const
Definition: vpDetectorBase.h:116
vpDetectorQRCode
Definition: vpDetectorQRCode.h:113
vpDetectorQRCode::detect
bool detect(const vpImage< unsigned char > &I)
Definition: vpDetectorQRCode.cpp:59
vpImage< unsigned char >
vpDetectorBase::getMessage
std::vector< std::string > & getMessage()
Definition: vpDetectorBase.h:106