Declaration of function and use it

[gauravsharma0190]

@jsulm
It crashes when i press the push button .
I debugged it and found it creshes when my function call.
Error found->it takes signal from OS.
Now How to fix it.

[jsulm]

@gauravsharma0190 How to fix what?
What do you mean by "Error found->it takes signal from OS" - what OS signal do you mean? Do you mean SIGABRT?
I don't know how to fix it because I have no idea what the problem is. But usually such problems are caused by bugs in applications. You have to check your code and see what is wrong at the line where your application crashes.

[jsulm]

@gauravsharma0190 Can you post the code and mark the line where it crashes?

[gauravsharma0190]

@jsulm
Mainwindow.cpp

void MainWindow::on_onTrackball_clicked()
{
    int threshold_value = 0;
    int threshold_type = 3;
    int const max_value = 255;
    int const max_type = 4;
   // int const max_BINARY_value = 255;

    Mat src, src_gray, dst;
  //  char* window_name = "Threshold Demo";

    //char* trackbar_type = "Type: \n 0: Binary \n 1: Binary Inverted \n 2: Truncate \n 3: To Zero \n 4: To Zero Inverted";
    //char* trackbar_value = "Value";




    /// Load image
    src = imread( "/home/pi/Desktop/b4.jpg");


      /// Convert the image to Gray
      cvtColor( src, src_gray, CV_BGR2GRAY );

      /// Create a window to display results
      namedWindow( "Threshold", CV_WINDOW_AUTOSIZE );

      /// Create Trackbar to choose type of Threshold
      createTrackbar( "Type: \n 0: Binary \n 1: Binary Inverted \n 2: Truncate \n 3: To Zero \n 4: To Zero Inverted","Threshold", &threshold_type, max_type, Threshold_Demo );

      createTrackbar( "value","Threshold", &threshold_value, max_value, Threshold_Demo );

      /// Call the function to initialize
@@@   ***Threshold_Demo( 0, 0)***


}

onTrack.h

#ifndef ONTRACKBALL_H_
#define ONTRACKBALL_H_
  void Threshold_Demo( int, void* );
#endif

ontrack.cpp

void Threshold_Demo( int, void* )
{
  /* 0: Binary
     1: Binary Inverted
     2: Threshold Truncated
     3: Threshold to Zero
     4: Threshold to Zero Inverted
   */

@@threshold( src_gray, dst, threshold_value, max_BINARY_value,threshold_type );

  imshow("Threshold", dst );

Here @---> Error

[jsulm]

@gauravsharma0190 What are src_gray, dst, threshold_value, max_BINARY_value,threshold_type? Where are they defined and initialized? Please note: these are NOT same as in MainWindow::on_onTrackball_clicked()!

void Threshold_Demo( int, void* )
{
  /* 0: Binary
     1: Binary Inverted
     2: Threshold Truncated
     3: Threshold to Zero
     4: Threshold to Zero Inverted
   */

@@threshold( src_gray, dst, threshold_value, max_BINARY_value,threshold_type );

  imshow("Threshold", dst );

[gauravsharma0190]

@jsulm
Hey Good morning
These are defined in the same function .cpp files.
Yes These are not in mainwindow

[jsulm]

@gauravsharma0190 Did you initialize these variables? Do they have correct values when you call threshold()?

[gauravsharma0190]

@jsulm
Yes i initialize these with correct values.

[jsulm]

@gauravsharma0190 Are you sure? Did you verify using debugger? If they have correct values then I don't know why it's crashing...

[gauravsharma0190]

@gauravsharma0190 said:

void MainWindow::on_onTrackball_clicked()
{
int threshold_value = 0;
int threshold_type = 3;
int const max_value = 255;
int const max_type = 4;
// int const max_BINARY_value = 255;

Mat src, src_gray, dst;

// char* window_name = "Threshold Demo";

//char* trackbar_type = "Type: \n 0: Binary \n 1: Binary Inverted \n 2: Truncate \n 3: To Zero \n 4: To Zero Inverted";
//char* trackbar_value = "Value";




/// Load image
src = imread( "/home/pi/Desktop/b4.jpg");


  /// Convert the image to Gray
  cvtColor( src, src_gray, CV_BGR2GRAY );

  /// Create a window to display results
  namedWindow( "Threshold", CV_WINDOW_AUTOSIZE );

  /// Create Trackbar to choose type of Threshold
  createTrackbar( "Type: \n 0: Binary \n 1: Binary Inverted \n 2: Truncate \n 3: To Zero \n 4: To Zero Inverted","Threshold", &threshold_type, max_type, Threshold_Demo );

  createTrackbar( "value","Threshold", &threshold_value, max_value, Threshold_Demo );

  /// Call the function to initialize

@@@ Threshold_Demo( 0, 0)

}

When I Comment the line Threshold _demo everything went OK!!!
Results are coming but when i uncomment it everything crashes.

[mrjj]

Hi
I have a teory ;)

namedWindow

void namedWindow(const string& winname, int flags=WINDOW_AUTOSIZE )

It wants a ref, so i assume that the crash is that
// char* window_name = "Threshold Demo";

will run out of scope

where as
namedWindow( "Threshold", CV_WINDOW_AUTOSIZE );
There "Threshold" is managed by the compiler and wont run out.

To test this, please move
char* window_name = "Threshold Demo";

OUTSIDE the function so it last longer than function call.

[jsulm]

@gauravsharma0190 Please take a closer look at this code:

void MainWindow::on_onTrackball_clicked()
{
int threshold_value = 0;
int threshold_type = 3;
int const max_value = 255;
int const max_type = 4;
// int const max_BINARY_value = 255;
// These variables are LOCAL!
Mat src, src_gray, dst;

You use local variables in void MainWindow::on_onTrackball_clicked(). All these variables exist only in that function: Mat src, src_gray, dst;
In Threshold_Demo() these variable are not visible (I have no idea why your code compiles? You probably defined these variables somewhere else again). I already pointed out this issue in one of my previous posts.

void Threshold_Demo( int, void* )
{
  /* 0: Binary
     1: Binary Inverted
     2: Threshold Truncated
     3: Threshold to Zero
     4: Threshold to Zero Inverted
   */
// src_gray, dst, threshold_value, max_BINARY_value,threshold_type are GLOBAL! Where are they defined?
@@threshold( src_gray, dst, threshold_value, max_BINARY_value,threshold_type );

Please make really sure src_gray, dst, threshold_value, max_BINARY_value,threshold_type have valid values when you call threshold( )! Use debugger for this.

[gauravsharma0190]

@jsulm
Hey the ontrack.cpp file has these variable defined i havn't sent you full code
here it is

#include"onTrack.h"
#include<imgproc.hpp>
 using namespace cv;
using namespace std;
int threshold_value=0;
int threshold_type=3;
int const max_BINARY_value=255;
Mat src_gray,dst;

void Threshold_Demo( int, void* )
{
  /* 0: Binary
     1: Binary Inverted
     2: Threshold Truncated
     3: Threshold to Zero
     4: Threshold to Zero Inverted
   */

  threshold( src_gray, dst, threshold_value, max_BINARY_value,threshold_type );

  imshow( window_name, dst );
}
......

[jsulm]

@gauravsharma0190 That is the problem I'm talking all the time! You do not initialize src_gray,dst from ontrack.cpp, so you use not properly initialized variables in Threshold_Demo(). As I said in MainWindow::on_onTrackball_clicked() you use local variables rc_gray,dst, not the ones from ontrack.cpp!
So, again where are these variables initialized?

// Where are they initialized?
Mat src_gray,dst;

void Threshold_Demo( int, void* )
{
  /* 0: Binary
     1: Binary Inverted
     2: Threshold Truncated
     3: Threshold to Zero
     4: Threshold to Zero Inverted
   */

[gauravsharma0190]

@jsulm said:

That is the problem I'm talking all the time! You do not initialize src_gray,dst from ontrack.cpp, so you use not properly initialized variables in Threshold_Demo(). As I said in MainWindow::on_onTrackball_clicked() you use local variables rc_gray,dst, not the ones from ontrack.cpp!
So, again where are these variables initialized?

// Where are they initialized?
Mat src_gray,dst;

void Threshold_Demo( int, void* )
{
/* 0: Binary
1: Binary Inverted
2: Threshold Truncated
3: Threshold to Zero
4: Threshold to Zero Inverted
*/

I initalized it in Mainwindow::onTrackBall_clicked().
I am sending you.
mainWindow.cpp*******

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include<opencv2/opencv.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/core/core.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include<QFileDialog>
#include<QMessageBox>
#include <iostream>
#include<QProcess>
#include "onTrackBall.h"
#include<syscall.h>
#include<signal.h>
#include <string>
#include<stdlib.h>
#include<sys/ioctl.h>
#include <fstream>
#include<time.h>
#include<QTimer>
#include<QDateTime>
//#include"onTrackBall.h"
//#include"onTrackBall.c"
using namespace cv;
using namespace std;


MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    QTimer *timer=new QTimer(this);
    connect(timer,SIGNAL(timeout()),this,SLOT(showTime()));
            timer->start();
            QDateTime dateTime=QDateTime::currentDateTime();
            QString datetimetext=dateTime.toString();
            ui->DateTime->setText(datetimetext);

}
void MainWindow::on_onTrackball_clicked()
{
    int threshold_value = 0;
    int threshold_type = 3;
    int const max_value = 255;
    int const max_type = 4;
   // int const max_BINARY_value = 255;

    Mat src, src_gray;





    /// Load image
    src = imread( "/home/pi/Desktop/b4.jpg");


      /// Convert the image to Gray
      cvtColor( src, src_gray, CV_BGR2GRAY );

      /// Create a window to display results
      namedWindow( "Threshold", CV_WINDOW_NORMAL );

      /// Create Trackbar to choose type of Threshold
      createTrackbar( "Type: \n 0: Binary \n 1: Binary Inverted \n 2: Truncate \n 3: To Zero \n 4: To Zero Inverted","Threshold", &threshold_type, max_type, Threshold_Demo );

      createTrackbar( "value","Threshold", &threshold_value, max_value, Threshold_Demo );

      /// Call the function to initialize
    Threshold_Demo( 0, 0 );


    /// Separate the image in 3 places ( B, G and R )
    vector<Mat> bgr_planes;
    split( src, bgr_planes );

    /// Establish the number of bins
    int histSize = 256;

    /// Set the ranges ( for B,G,R) )
    float range[] = { 0, 256 } ;
    const float* histRange = { range };

    bool uniform = true;
    bool accumulate = false;

    Mat b_hist, g_hist, r_hist;

    /// Compute the histograms:
    calcHist( &bgr_planes[0], 1, 0, Mat(), b_hist, 1, &histSize, &histRange, uniform, accumulate );
    calcHist( &bgr_planes[1], 1, 0, Mat(), g_hist, 1, &histSize, &histRange, uniform, accumulate );
    calcHist( &bgr_planes[2], 1, 0, Mat(), r_hist, 1, &histSize, &histRange, uniform, accumulate );

    // Draw the histograms for B, G and R
    int hist_w = 512; int hist_h = 400;
   int bin_w = cvRound( (double) hist_w/histSize );

    Mat histImage( hist_h, hist_w, CV_8UC3, Scalar( 0,0,0) );

    /// Normalize the result to [ 0, histImage.rows ]
    normalize(b_hist, b_hist, 0, histImage.rows, NORM_MINMAX, -1, Mat() );
    normalize(g_hist, g_hist, 0, histImage.rows, NORM_MINMAX, -1, Mat() );
    normalize(r_hist, r_hist, 0, histImage.rows, NORM_MINMAX, -1, Mat() );

    /// Draw for each channel
    for( int i = 1; i < histSize; i++ )
    {
        line( histImage, Point( bin_w*(i-1), hist_h - cvRound(b_hist.at<float>(i-1)) ) ,
                         Point( bin_w*(i), hist_h - cvRound(b_hist.at<float>(i)) ),
                         Scalar( 255, 0, 0), 2, 8, 0  );
        line( histImage, Point( bin_w*(i-1), hist_h - cvRound(g_hist.at<float>(i-1)) ) ,
                         Point( bin_w*(i), hist_h - cvRound(g_hist.at<float>(i)) ),
                         Scalar( 0, 255, 0), 2, 8, 0  );
        line( histImage, Point( bin_w*(i-1), hist_h - cvRound(r_hist.at<float>(i-1)) ) ,
                         Point( bin_w*(i), hist_h - cvRound(r_hist.at<float>(i)) ),
                         Scalar( 0, 0, 255), 2, 8, 0  );
    }

    /// Display
    namedWindow("calcHist Demo", CV_WINDOW_NORMAL );
    imshow("calcHist Demo", histImage );
  imwrite("calcHist Demo2.jpg", histImage);
waitKey(-1);


  }
...

[jsulm]

@gauravsharma0190 Please read what I'm writing more carefully!
In Mainwindow::onTrackBall_clicked() you don't initialize them! Because you use local variables there with same names:

void MainWindow::on_onTrackball_clicked()
{
     // Here src and src_gray are not the same as in ontrack.cpp!
     // Values you're assigning here to src and src_gray are only visible here but not in ontrack.cpp!
    Mat src, src_gray;

I'm running out of ideas how to explain it. You should learn C++, especially the visibility and scope of variables.

[gauravsharma0190]

@jsulm
You mean to say in OnTrack_clicked()
src and src_gray variable
and in ontrack.cpp
src_gray variable should be different.
I can't get you.
In Mainwindow::onTrackBall_clicked() you don't initialize them! Because you use local variables there with same names:

void MainWindow::on_onTrackball_clicked()
{
// Here src and src_gray are not the same as in ontrack.cpp!
// Values you're assigning here to src and src_gray are only visible here but not in ontrack.cpp!
Here what is local variable in it.
Local mean variable inside the function??
And globle mean en tire the programme.

[jsulm]

@gauravsharma0190 No, I don't mean that they should be different. I mean the opposite: they need to be the same (but they are not).
Local variable is a variable which is only visible in a certain scope, for example in a function. The variables in ontrack.cpp are only visible in ontrack.cpp, but not in MainWindow. In Mainwindow::onTrackBall_clicked() you declare OTHER variables with SAME names.
What do you think which src_grey is used in Threshold_Demo( int, void* )? Is it the one from MainWindow::onTrackBall_clicked() or the one from ontrack.cpp?

// src_gray here is not the same as in MainWindow::onTrackBall_clicked()
Mat src_gray,dst;
void Threshold_Demo( int, void* )
{
  threshold( src_gray, dst, threshold_value, max_BINARY_value,threshold_type );
}

Actually you should pass the data to Threshold_Demo() as parameter:

Mainwindow::onTrackBall_clicked()
{
    Mat src, src_gray;
    ...
    Threshold_Demo(src_grey, /*what else needs to be passed from MainWindow to this function*/);
    ...
}

void Threshold_Demo(Mat &src_grey, ...)
{

[gauravsharma0190]

@jsulm
OK it means src_gray value in .cpp file should be same as in mainwindow::on_Track clicked() src_gray value.
Actually src_gray is image array.
I did it by Define the value of src_grey in function as
src=imread("/file.jpg);
cvtColor( src, src_gray, CV_BGR2GRAY );
so i will get src_gray value.