How to convolve using for loops in opencv c++? [closed] - c++

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I am not getting proper output with current data types in the program.
I am getting a very undesired and unexpectedly large values while accessing each element as well
#include <opencv2/opencv.hpp>
#include <iostream>
/*
Specifying Namespaces
Namespace is a declarative region that provides a scope to the identifiers (the names of types, functions, variables, etc) inside it.
*/
using namespace std;
using namespace cv;
/// #brief : Convolution will help apply different kernels to your images yielding different results
/// #param Original_image
/// #param kernel
/// #return : An Output Image with the kernel applied
Mat convolve(Mat kernel, Mat original_image){
Mat kernel_inv;
Mat resultant_image{original_image.size(), original_image.type()};
// Just checking whether these funcitons are continuous or not
kernel_inv.isContinuous();
kernel.isContinuous();
// ################################ Flip Kernel Suboptimally ######################## //
// Method 2: Simply using in-built functions
flip(kernel, kernel_inv, -1);
// #################################################################################### //
for (int i = 1; i < original_image.rows; i++)
{
for (int j = 1; j < original_image.cols; j++)
{
double tmp = 0.0;
for (int k = 0; k < kernel_inv.rows; k++)
{
for (int l = 0; l < kernel_inv.cols; l++)
{
int x = j - 1 + l;
int y = i - 1 + k;
if ((x >= 0 && x < original_image.cols) && (y >= 0 && y < original_image.rows)){
tmp += (int)original_image.at<u_char>(y, x) * (int)kernel_inv.at<u_char>(k, l);
}
}
}
resultant_image.at<u_char>(i, j) = saturate_cast<char>(tmp);
}
}
return resultant_image;
}
int main( int argc, char** argv )
{
Mat image = imread("../dog_test.png",IMREAD_GRAYSCALE); // Read Image
Mat img2;
// Format for last argument in Create, ones and zero
// CV_[The number of bits per item][Signed or Unsigned][Type Prefix]C[The channel number]
/*
// Try These Lines by uncommenting the code one by one
// kernel.create(4,4, CV_8UC(2)); // Just to create a matrix
// kernel = Mat::ones(4,4, CV_64F); // Just to create matrix with all entries 1
// kernel = Mat::eye(4,4, CV_32F); // Just to create matrix with all entries 0
*/
double sobelx_data[9] = {0.111, 0.111, 0.111, 0.111, 0.111, 0.111, 0.111, 0.111, 0.111};
Mat sobelx = cv::Mat(3, 3, CV_32F, sobelx_data);
// cout<<image<<endl<<endl;
img2 = convolve(sobelx, image);
cout<<"Original: "<<(int)image.at<u_char>(100,250)<<endl;
cout<<"img2: "<<(int)img2.at<u_char>(100,250)<<endl;
// cout<<"OUTPUT = \n"<<img2<<endl<<endl;
// Functions to show images
namedWindow("Copy", WINDOW_NORMAL);
imshow("Copy", img2);
// Resizing the Window for Better Visualization
waitKey(0);
return 0;
}
I have tried to access the elements using .at attribute in cv mat, which gives arbitrary values, so another problem is how to determine the type of the elements used in the matrix
So, this was the method that I tried, so if anyone can help me it will be great.