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EdgeDetection.cpp
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EdgeDetection.cpp
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#include "EdgeDetection.h"
#include <iostream>
using namespace std;
using namespace cv;
/*
* function to implement median filter
* params : CV::Mat object image
* first it selects the neighbouring 8 pixels for each pixel in the picture, then sort them and inject the median in the current pix
*/
Mat toGreyScale(Mat image)
{
for (int i = 0; i < image.rows; i++)
for (int j = 0; j < image.cols; j++)
{
Vec3b rgbPixel = image.at<Vec3b>(i, j); // we get pixel at each postion
unsigned char grayScale = (rgbPixel[2] + rgbPixel[1] + rgbPixel[0]) / 3;
image.at<Vec3b>(i, j) = { grayScale ,grayScale ,grayScale };
}
return image;
}
/*
* function to implement median filter
* params : CV::Mat object image
* first it selects the neighbouring 8 pixels for each pixel in the picture, then sort them and inject the median in the current pix
*/
int(*(getArray)(std::string mode, std::string direction))[3]
{
if (mode == "Sobel") {
if (direction == "vertical") {
static int mask[3][3] = { {-1,-2,-1},{0,0,0},{1,2,1} };
return mask;
}
else {
static int mask[3][3] = { {-1,0,1},{-2,0,2},{-1,0,1} };
return mask;
}
}
if (mode == "Roberts") {
if (direction == "vertical") {
static int mask[3][3] = { {0,0,0},{0,-1,0},{0,0,1} };
return mask;
}
else {
static int mask[3][3] = { {0,0,0},{0,1,0},{0,0,-1} };
return mask;
}
}
else if(mode =="Prewitt") {
if (direction == "vertical") {
static int mask[3][3] = { {-1,-1,-1},{0,0,0},{1,1,1} };
return mask;
}
else {
static int mask[3][3] = { {-1,0,1},{-1,0,1},{-1,0,1} };
return mask;
}
}
}
/*
* function to implement median filter
* params : CV::Mat object image
* first it selects the neighbouring 8 pixels for each pixel in the picture, then sort them and inject the median in the current pix
*/
Mat masking(Mat image,int mask[3][3])
{
Mat temImage = image.clone();
for (int i = 1; i < image.rows - 1; i++)
for (int j = 1; j < image.cols - 1; j++)
{
int pixel1 = image.at<uchar>(i - 1, j - 1) * mask[0][0];
int pixel2 = image.at<uchar>(i, j - 1) * mask[0][1];
int pixel3 = image.at<uchar>(i + 1, j - 1) * mask[0][2];
int pixel4 = image.at<uchar>(i - 1, j) * mask[1][0];
int pixel5 = image.at<uchar>(i, j) * mask[1][1];
int pixel6 = image.at<uchar>(i + 1, j) * mask[1][2];
int pixel7 = image.at<uchar>(i - 1, j + 1) * mask[2][0];
int pixel8 = image.at<uchar>(i, j + 1) * mask[2][1];
int pixel9 = image.at<uchar>(i + 1, j + 1) * mask[2][2];
int sum = pixel1 + pixel2 + pixel3 + pixel4 + pixel5 + pixel6 + pixel7 + pixel8 + pixel9;
if (sum < 0) sum = 0;
if (sum > 255) sum = 255;
temImage.at<uchar>(i, j) = sum;
}
return temImage;
}
/*
* function to implement median filter
* params : CV::Mat object image
* first it selects the neighbouring 8 pixels for each pixel in the picture, then sort them and inject the median in the current pix
*/
void non_max_suppression(Mat& magnitude,Mat& direction,Mat& result)
{
// Create a copy of the magnitude matrix
result = magnitude.clone();
// Suppress non-maximum points
for (int y = 1; y < magnitude.rows - 1; y++)
for (int x = 1; x < magnitude.cols - 1; x++)
{
// Calculate the angle of the gradient at this pixel
float angle = direction.at<float>(y, x) * 180.0 / CV_PI;
// Wrap the angle around 180 degrees
if (angle < 0) {
angle += 180;
}
// Find the two neighboring pixels along the gradient direction
int x1, y1, x2, y2;
if (angle < 22.5 || angle >= 157.5) {
x1 = x2 = x;
y1 = y - 1;
y2 = y + 1;
}
else if (angle < 67.5) {
x1 = x - 1;
y1 = y - 1;
x2 = x + 1;
y2 = y + 1;
}
else if (angle < 112.5) {
x1 = x - 1;
y1 = y;
x2 = x + 1;
y2 = y;
}
else {
x1 = x - 1;
y1 = y + 1;
x2 = x + 1;
y2 = y - 1;
}
// Suppress the point if its magnitude is smaller than either of its neighbors
float mag = magnitude.at<float>(y, x);
float mag1 = magnitude.at<float>(y1, x1);
float mag2 = magnitude.at<float>(y2, x2);
if (mag < mag1 || mag < mag2) {
result.at<float>(y, x) = 0;
}
}
}
/*
* function to implement median filter
* params : CV::Mat object image
* first it selects the neighbouring 8 pixels for each pixel in the picture, then sort them and inject the median in the current pix
*/
Mat CannyEdgeDetection(Mat image, int segma, int lowThreshold, int highThreshold, int KernalSize)
{
if(KernalSize%2==0) KernalSize=KernalSize+1;
Mat Blured, magnitude, direction, result;
int(*maskH)[3];
int(*maskV)[3];
//Gussian Bluring
GaussianBlur(image, Blured, Size(KernalSize, KernalSize), segma, segma);
maskH = getArray("Sobel", "horizontal");
maskV = getArray("Sobel", "vertical");
//Sobel Edge detection in both vertical and horizontal directions
Mat gradientx = masking(Blured, maskH);
Mat gradienty = masking(Blured, maskV);
gradientx.convertTo(gradientx, CV_32F);
gradienty.convertTo(gradienty, CV_32F);
cartToPolar(gradientx, gradienty, magnitude, direction, true);
non_max_suppression(magnitude, direction, result);
inRange(result, Scalar(lowThreshold), Scalar(highThreshold), result);
return result;
}