ch04 utils

#python code

import cv2
import numpy as np

def mask_setTo():
    src = cv2.imread("D:\\projects\\SampleCode\\006939-master\\ch04\\utils\\lenna.bmp", cv2.IMREAD_COLOR)
    mask = cv2.imread("D:\\projects\\SampleCode\\006939-master\\ch04\\utils\\mask_smile.bmp", cv2.IMREAD_GRAYSCALE)

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

    src[mask > 0] = (0, 255, 255)

    cv2.imshow("src", src)
    cv2.imshow("mask", mask)
    cv2.waitKey(0)
    cv2.destroyAllWindows()

def mask_copyTo():
    src = cv2.imread("D:\\projects\\SampleCode\\006939-master\\ch04\\utils\\airplane.bmp", cv2.IMREAD_COLOR)
    mask = cv2.imread("D:\\projects\\SampleCode\\006939-master\\ch04\\utils\\mask_plane.bmp", cv2.IMREAD_GRAYSCALE)
    dst = cv2.imread("D:\\projects\\SampleCode\\006939-master\\ch04\\utils\\field.bmp", cv2.IMREAD_COLOR)

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

    dst[mask > 0] = src[mask > 0]

    cv2.imshow("src", src)
    cv2.imshow("dst", dst)
    cv2.imshow("mask", mask)
    cv2.waitKey(0)
    cv2.destroyAllWindows()

def time_inverse():
    src = cv2.imread("D:\\projects\\SampleCode\\006939-master\\ch04\\utils\\lenna.bmp", cv2.IMREAD_GRAYSCALE)

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

    dst = cv2.bitwise_not(src)

    cv2.imshow("src", src)
    cv2.imshow("dst", dst)
    cv2.waitKey(0)
    cv2.destroyAllWindows()

def useful_func():
    img = cv2.imread("D:\\projects\\SampleCode\\006939-master\\ch04\\utils\\lenna.bmp", cv2.IMREAD_GRAYSCALE)

    print("Sum:", np.sum(img))
    print("Mean:", np.mean(img))

    minVal, maxVal, minPos, maxPos = cv2.minMaxLoc(img)

    print("minVal:", minVal, "at", minPos)
    print("maxVal:", maxVal, "at", maxPos)

    src = np.array([-1.0, -0.5, 0.0, 0.5, 1.0], dtype=np.float32)
    dst = cv2.normalize(src, None, 0, 255, cv2.NORM_MINMAX, cv2.CV_8UC1)

    print("src:", src)
    print("dst:", dst)

    print("cv2.round(2.5):",  round(2.5))
    print("cv2.round(2.51):",  round(2.51))
    print("cv2.round(3.4999):", round(3.4999))
    print("cv2.round(3.5):", round(3.5))

def main():
    mask_setTo()
    mask_copyTo()
    time_inverse()
    useful_func()

if __name__ == "__main__":
    main()

---

// C++  code

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

using namespace cv;
using namespace std;

void mask_setTo();
void mask_copyTo();
void time_inverse();
void useful_func();

int main(void)
{
	mask_setTo();
	mask_copyTo();
	time_inverse();
	useful_func();

	return 0;
}

void mask_setTo()
{
	Mat src = imread("lenna.bmp", IMREAD_COLOR);
	Mat mask = imread("mask_smile.bmp", IMREAD_GRAYSCALE);

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

	src.setTo(Scalar(0, 255, 255), mask);

	imshow("src", src);
	imshow("mask", mask);

	waitKey(0);
	destroyAllWindows();
}

void mask_copyTo()
{
	Mat src = imread("airplane.bmp", IMREAD_COLOR);
	Mat mask = imread("mask_plane.bmp", IMREAD_GRAYSCALE);
	Mat dst = imread("field.bmp", IMREAD_COLOR);

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

	src.copyTo(dst, mask);

	imshow("src", src);
	imshow("dst", dst);
	imshow("mask", mask);

	waitKey(0);
	destroyAllWindows();
}

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

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

	Mat dst(src.rows, src.cols, src.type());

	TickMeter tm;
	tm.start();

	for (int j = 0; j < src.rows; j++) {
		for (int i = 0; i < src.cols; i++) {
			dst.at<uchar>(j, i) = 255 - src.at<uchar>(j, i);
		}
	}

	tm.stop();
	cout << "Image inverse took " << tm.getTimeMilli() << "ms." << endl;
}

void useful_func()
{
	Mat img = imread("lenna.bmp", IMREAD_GRAYSCALE);

	cout << "Sum: " << (int)sum(img)[0] << endl;
	cout << "Mean: " << (int)mean(img)[0] << endl;

	double minVal, maxVal;
	Point minPos, maxPos;
	minMaxLoc(img, &minVal, &maxVal, &minPos, &maxPos);

	cout << "minVal: " << minVal << " at " << minPos << endl;
	cout << "maxVal: " << maxVal << " at " << maxPos << endl;

	Mat src = Mat_<float>({ 1, 5 }, { -1.f, -0.5f, 0.f, 0.5f, 1.f });

	Mat dst;
	normalize(src, dst, 0, 255, NORM_MINMAX, CV_8UC1);

	cout << "src: " << src << endl;
	cout << "dst: " << dst << endl;

	cout << "cvRound(2.5): " << cvRound(2.5) << endl;
	cout << "cvRound(2.51): " << cvRound(2.51) << endl;
	cout << "cvRound(3.4999): " << cvRound(3.4999) << endl;
	cout << "cvRound(3.5): " << cvRound(3.5) << endl;
}

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

---

Sum: 32518590
Mean: 124.04857635498047
minVal: 25.0 at (508, 71)
maxVal: 245.0 at (116, 273)
src: [-1.  -0.5  0.   0.5  1. ]
dst: [[  0]
 [ 64]
 [128]
 [191]
 [255]]
cv2.round(2.5): 2
cv2.round(2.51): 3
cv2.round(3.4999): 3
cv2.round(3.5): 4