ch09 edges

#python 

import cv2
import numpy as np

def sobel_derivative():
    src = cv2.imread("D:\\projects\\SampleCode\\006939-master\\ch09\\edges\\lenna.bmp", cv2.IMREAD_GRAYSCALE)

    if src is None:
        print("Image load failed!")
        return

    mx = np.float32([[-1/2.0, 0, 1/2.0]])
    my = np.float32([[-1/2.0], [0], [1/2.0]])

    dx = cv2.filter2D(src, -1, mx, delta=128)
    dy = cv2.filter2D(src, -1, my, delta=128)

    cv2.imshow("src", src)
    cv2.imshow("dx", dx)
    cv2.imshow("dy", dy)
    cv2.waitKey(0)
    cv2.destroyAllWindows()

def sobel_edge():
    src = cv2.imread("D:\\projects\\SampleCode\\006939-master\\ch09\\edges\\lenna.bmp", cv2.IMREAD_GRAYSCALE)

    if src is None:
        print("Image load failed!")
        return

    dx = cv2.Sobel(src, cv2.CV_32F, 1, 0)
    dy = cv2.Sobel(src, cv2.CV_32F, 0, 1)

    fmag = np.sqrt(dx**2 + dy**2)
    mag = np.clip(fmag, 0, 255).astype(np.uint8)

    edge = np.uint8((mag > 150)*255)

    cv2.imshow("src", src)
    cv2.imshow("mag", mag)
    cv2.imshow("edge", edge)
    cv2.waitKey(0)
    cv2.destroyAllWindows()

def canny_edge():
    src = cv2.imread("D:\\projects\\SampleCode\\006939-master\\ch09\\edges\\lenna.bmp", cv2.IMREAD_GRAYSCALE)

    if src is None:
        print("Image load failed!")
        return

    dst1 = cv2.Canny(src, 50, 100)
    dst2 = cv2.Canny(src, 50, 150)

    cv2.imshow("src", src)
    cv2.imshow("dst1", dst1)
    cv2.imshow("dst2", dst2)
    cv2.waitKey(0)
    cv2.destroyAllWindows()

def main():
    sobel_derivative()
    sobel_edge()
    canny_edge()

if __name__ == "__main__":
    main()

---

// C++

#include "opencv2/opencv.hpp"
#include <iostream>

using namespace cv;
using namespace std;

void sobel_derivative();
void sobel_edge();
void canny_edge();

int main(void)
{
	sobel_derivative();
	sobel_edge();
	canny_edge();

	return 0;
}

void sobel_derivative()
{
	Mat src = imread("lenna.bmp", IMREAD_GRAYSCALE);

	if (src.empty()) {
		cerr << "Image load failed!" << endl;
		return;
	}

	Mat mx = Mat_<float>({ 1, 3 }, { -1 / 2.f, 0, 1 / 2.f });
	Mat my = Mat_<float>({ 3, 1 }, { -1 / 2.f, 0, 1 / 2.f });

	Mat dx, dy;
	filter2D(src, dx, -1, mx, Point(-1, -1), 128);
	filter2D(src, dy, -1, my, Point(-1, -1), 128);

	imshow("src", src);
	imshow("dx", dx);
	imshow("dy", dy);

	waitKey();
	destroyAllWindows();
}

void sobel_edge()
{
	Mat src = imread("lenna.bmp", IMREAD_GRAYSCALE);

	if (src.empty()) {
		cerr << "Image load failed!" << endl;
		return;
	}

	Mat dx, dy;
	Sobel(src, dx, CV_32FC1, 1, 0);
	Sobel(src, dy, CV_32FC1, 0, 1);

	Mat fmag, mag;
	magnitude(dx, dy, fmag);
	fmag.convertTo(mag, CV_8UC1);

	Mat edge = mag > 150;

	imshow("src", src);
	imshow("mag", mag);
	imshow("edge", edge);

	waitKey();
	destroyAllWindows();
}

void canny_edge()
{
	Mat src = imread("lenna.bmp", IMREAD_GRAYSCALE);

	if (src.empty()) {
		cerr << "Image load failed!" << endl;
		return;
	}

	Mat dst1, dst2;
	Canny(src, dst1, 50, 100);
	Canny(src, dst2, 50, 150);

	imshow("src", src);
	imshow("dst1", dst1);
	imshow("dst2", dst2);

	waitKey();
	destroyAllWindows();
}

C++ Code 출처 : OpenCV 4로 배우는 컴퓨터 비전과 머신 러닝 - 황선규 저

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