Thanks for your replay.I have flow your instruction.But i need to calculate the angle,How many degree, example 45 degree, in my screen it will show 45 degree. Mat magnitude,angl; cartToPolar(planes[0],planes[1], magnitude,angl,true); cout << "degree=" <<true << endl; log(magnitude,magnitude); magnitude = magnitude(Rect(0, 0, magnitude.cols & -2, magnitude.rows & -2));

I am new in opencv. After completing Fourier transform, i have also got display the angle.I want to show in my window how many degree it is.please give me some idea.

// crop the spectrum, if it has an odd number of rows or columns
    canny_image = canny_image(Rect(0, 0, canny_image.cols & -2, canny_image.rows & -2));


 // rearrange the quadrants of Fourier image  so that the origin is at the image center
    int cx = canny_image.cols/2;
    int cy = canny_image.rows/2;

    Mat q0(canny_image, Rect(0, 0, cx, cy));   // Top-Left - Create a ROI per quadrant
    Mat q1(canny_image, Rect(cx, 0, cx, cy));  // Top-Right
    Mat q2(canny_image, Rect(0, cy, cx, cy));  // Bottom-Left
    Mat q3(canny_image, Rect(cx, cy, cx, cy)); // Bottom-Right

    Mat tmp;                           // swap quadrants (Top-Left with Bottom-Right)
    q0.copyTo(tmp);
    q3.copyTo(q0);
    tmp.copyTo(q3);

    q1.copyTo(tmp);                    // swap quadrant (Top-Right with Bottom-Left)
    q2.copyTo(q1);
    tmp.copyTo(q2);

    normalize(canny_image, canny_image, 0, 1, CV_MINMAX); // Transform the matrix with float values into a
                                            // viewable image form (float between values 0 and 1).
 imshow("spectrum magnitude", canny_image);

Hello, I have an image I applied the fourier transform for the orientation angle,but i face here channels problem.When i build this program,it shows success but it's not run.It is showing "Open cv Error: Assertion failed <_tp>::channels==m.channels<>>in unknown function, file c:\opencv\opencv\build\include\opencv2/core/mat.hpp,line890" i used Breakpoint in this code when it comes this line "Mat planes[] = {Mat_(padded), Mat::zeros(padded.size(), CV_32F)};"then it break.Personally I do not know how i solve this problem because I have no error! Please help me

#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/highgui/highgui.hpp"
#include <stdlib.h>
#include <stdio.h>
#include <opencv2\opencv.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/core/core.hpp>
#include <stdint.h>
#include <opencv2/imgproc/imgproc.hpp>
#include <iostream>

using namespace cv;
using namespace std;
/// Global variables
Mat src, src_gray,canny_image,padded,good_f_t, threshold_image,lowerRect,imageROI,dst, detected_edges;
int edgeThresh = 1;
int lowThreshold;
int const max_lowThreshold = 100;
int ratio = 3;
int kernel_size = 3;
char* window_name = "Edge Map";
void CannyThreshold(int, void*)
{
  blur( src_gray, detected_edges, Size(3,3) );
    Canny( detected_edges, detected_edges, lowThreshold, lowThreshold*ratio, kernel_size );
    dst = Scalar::all(0);
    src.copyTo( dst, detected_edges);
    imshow( window_name, dst );
   Mat padded;                           
    int m = getOptimalDFTSize( dst.rows );
    int n = getOptimalDFTSize( dst.cols ); 
    copyMakeBorder(dst, padded, 0, m - dst.rows, 0, n - dst.cols, BORDER_CONSTANT, Scalar::all(0));
    Mat planes[] = {Mat_<float>(padded), Mat::zeros(padded.size(), CV_32F)};      
    Mat complexdst;
    merge(planes, 2, complexdst);        
    dft(complexdst, complexdst);            

    split(complexdst, planes);                   
    magnitude(planes[0], planes[1], planes[0]);
    Mat magdst = planes[0];
    magdst += Scalar::all(1);                    
    log(magdst, magdst);
    magdst = magdst(Rect(0, 0, magdst.cols & -2, magdst.rows & -2));
    int cx = magdst.cols/2;
    int cy = magdst.rows/2;
    Mat q0(magdst, Rect(0, 0, cx, cy));   
    Mat q1(magdst, Rect(cx, 0, cx, cy));  
    Mat q2(magdst, Rect(0, cy, cx, cy));  
    Mat q3(magdst, Rect(cx, cy, cx, cy));
     Mat tmp;                           
    q0.copyTo(tmp);
    q3.copyTo(q0);
    tmp.copyTo(q3);

    q1.copyTo(tmp);                    
    q2.copyTo(q1);
    tmp.copyTo(q2);

    normalize(magdst, magdst, 0, 1, CV_MINMAX); 
    imshow("spectrum magnitude", magdst);
    }


int main( int argc, char** argv )
{
    src = imread("C:/Users/Saha/Desktop/DSCF0563.JPG");
    resize(src, src, Size(), 0.2, 0.2, INTER_LANCZOS4);

  if( !src.data )
  { return -1; }

 dst.create( src.size(), src.type() );

 cvtColor( src, src_gray, CV_BGR2GRAY );

 namedWindow( window_name, CV_WINDOW_AUTOSIZE );

   createTrackbar( "Min Threshold:", window_name, &lowThreshold, max_lowThreshold, CannyThreshold );

    CannyThreshold(0, 0);

    waitKey(0);

  return 0;
  }

After performing canny , how do i access bright pixel? Also how can take those out using region of interest?

After performing canny , how do i access bright pixel? Also how can take those out using region of interest?