Visual Servoing Platform  version 3.6.1 under development (2024-05-26)
vpDetectorQRCode Class Reference

#include <visp3/detection/vpDetectorQRCode.h>

+ Inheritance diagram for vpDetectorQRCode:

Public Member Functions

 vpDetectorQRCode ()
 
bool detect (const vpImage< unsigned char > &I) vp_override
 
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)
 
void setTimeout (unsigned long timeout_ms)
 

Protected Attributes

zbar::ImageScanner m_scanner
 
std::vector< std::vector< vpImagePoint > > m_polygon
 
std::vector< std::string > m_message
 
size_t m_nb_objects
 
unsigned long m_timeout_ms
 

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
}
std::vector< std::vector< vpImagePoint > > & getPolygon()
size_t getNbObjects() const
std::vector< std::string > & getMessage()
bool detect(const vpImage< unsigned char > &I) vp_override
static void read(vpImage< unsigned char > &I, const std::string &filename, int backend=IO_DEFAULT_BACKEND)
Definition: vpImageIo.cpp:143

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 109 of file vpDetectorQRCode.h.

Constructor & Destructor Documentation

◆ vpDetectorQRCode()

vpDetectorQRCode::vpDetectorQRCode ( )

Default constructor.

Definition at line 45 of file vpDetectorQRCode.cpp.

References m_scanner.

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 57 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()

◆ getCog()

vpImagePoint vpDetectorBase::getCog ( size_t  i) const
inherited

◆ getMessage() [1/2]

std::vector<std::string>& vpDetectorBase::getMessage ( )
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 65 of file vpDetectorBase.cpp.

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

◆ getNbObjects()

◆ getPolygon() [1/2]

◆ 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 51 of file vpDetectorBase.cpp.

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

◆ setTimeout()

void vpDetectorBase::setTimeout ( unsigned long  timeout_ms)
inlineinherited

Set detector timeout in milli-seconds. When set to 0, there is no timeout.

Definition at line 129 of file vpDetectorBase.h.

Referenced by vpDetectorDataMatrixCode::vpDetectorDataMatrixCode().

Member Data Documentation

◆ m_message

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

◆ m_nb_objects

size_t vpDetectorBase::m_nb_objects
protectedinherited

Number of detected objects.

Definition at line 67 of file vpDetectorBase.h.

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

◆ m_polygon

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

◆ m_scanner

zbar::ImageScanner vpDetectorQRCode::m_scanner
protected

QR code detector.

Definition at line 112 of file vpDetectorQRCode.h.

Referenced by detect(), and vpDetectorQRCode().

◆ m_timeout_ms

unsigned long vpDetectorBase::m_timeout_ms
protectedinherited

Detection timeout.

Definition at line 68 of file vpDetectorBase.h.

Referenced by vpDetectorDataMatrixCode::detect().