Error with ROI OpenCV

I am trying to create a program that will identify the pattern by traversing the ROI over the image and comparing the ROI to the pattern, it will compare the pixel values ​​of the ROI and the pattern and increment the counter by 1 every time there are pixel matches, then I compare the counter with the threshold if it passes rectangle, will be drawn, if not, it will keep sliding over the image, if I run the debugger on it, it doesn't detect errors sliding over the image, but if I run it then it throws the following exception:

OpenCV Error: Assertion failed (0 <= roi.x && 0 <= roi.width && roi.x + roi.width <= m.cols && 0 <= roi.y && 0 <= roi.height && roi.y + roi.height <= m.rows) in Mat, file /home/abuild/rpmbuild/BUILD/opencv-2.4.6.1/modules/core/src/matrix.cpp, line 323
terminate called after throwing an instance of 'cv::Exception'
what():  /home/abuild/rpmbuild/BUILD/opencv-2.4.6.1/modules/core/src/matrix.cpp:323: error: (-215) 0 <= roi.x && 0 <= roi.width && roi.x + roi.width <= m.cols && 0 <= roi.y && 0 <= roi.height && roi.y + roi.height <= m.rows in function Mat

      

        
        
        
      

    

I am leaving the code below:

#include <stdio.h>
#include <stdlib.h>
#include <iostream>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/core/core.hpp>
#include <opencv2/imgproc/imgproc.hpp>


using namespace std;
using namespace cv;

Mat         iOrig;                          //imagen que se analizara
Mat         patron;                         //patron buscado
Point       corner1,corner2;                //esquinas del ROI
bool        tresholdpass;                   //boolean returned by comparar()
Rect        box;                            //rectangulo usado para crear el ROI
float       porcentaje;                     //distancia a recorrer que sera dada por el tamano de la imagen muestra para el patron
float       treshold;                       //treshold que debera ser superado para que se considere similar o igual al patron
float       valpx;                          //valor almacenado en el pixel comparado
float       contTreshold;                   //contador a comparar contra el porcentaje requerido para considerarse como patron encontrado
float       totpxpat;                       //cantidad de pixeles de la imagen muestra del patron
float       porctreshold;                   //porcentaje representativo para considerar que se encontro el patron en esa ROI

bool comparar(Mat region, Mat patron){

    int i=0;
    int j=0;
    contTreshold=0;

    for (i=0;i<patron.cols;i++){
        for (j=0;j<patron.rows;j++){
            Point a(i,j);
            if(abs(region.at<float>(a))==abs(patron.at<float>(a))){
            //se compara el contenido de el ROI y el patron en un punto
                contTreshold++;             //en caso de ser cierto, el contador aumenta en 1
            }
        }

    }
    totpxpat = patron.rows*patron.cols;     //se cuentan la cantidad de pixeles dado columnas*renglones
    porctreshold = 0.8;                     //el porcentaje que se usara para el treshold
    treshold = totpxpat * porctreshold;     //el treshold que determinara si se cumple el porcentaje de la imagen
                                        //para saber si cumple el patron o no, en caso de q se supere, retornara verdadero
                                        //en caso de que no se supere retornara falso y se elegira otro ROI para analizar
    if (contTreshold>treshold){
        return true;
    }else{
        return false;
    }
}

int main() {

    namedWindow("imagen");
    namedWindow("segmento");

    iOrig = imread( "/home/diego/Downloads/figuras.jpg",CV_LOAD_IMAGE_GRAYSCALE );
    patron = imread("/home/diego/Downloads/patron.jpg",CV_LOAD_IMAGE_GRAYSCALE);

    imshow("imagen",iOrig);
    imshow("segmento",patron);
    corner1.x = 1;
    corner1.y = 1;
    corner2.x = patron.cols;
    corner2.y = patron.rows;


    porcentaje = (int)patron.cols * 0.05;

    while (corner2.x<iOrig.rows-(patron.rows*2)){
        while(corner2.y<iOrig.cols-(patron.cols*2)){
            box.width = abs (corner1.x-corner2.x)+1;
            box.height = abs (corner1.y - corner2.y)+1;
            box.x = min(corner1.x, corner2.x);
            box.y = min(corner1.y, corner2.y);


        //se crea una imagen de la region de interes seleccionada apartir de las 2 esquinas de la ROI
            Mat     region(iOrig,box);              //region de interes que sera comparada

        //se manda a comparar el ROI con el patron
            tresholdpass=comparar(region,patron);
            if (tresholdpass == true){
                Mat local_img = iOrig.clone();
                rectangle(local_img,corner1,corner2,Scalar(0,0,255));
                imshow("imagen",local_img);

            }
            corner1.x+=porcentaje;
            corner2.x+=porcentaje;
        }
        corner1.y+=porcentaje;
        corner2.y+=porcentaje;
    }

    while (char(waitKey(1))!= 'q'){}
    return 0;
}

      

        
        
        
      

    

I cant load images im using due to reputation ... but original image is 800 x 450 and template, search in image is 131 x 132

Sorry that the comments in my code are in Spanish, English is not my native language, you guessed it, I really don't know where my mistake is, but ... I hope this is just thanks in advance