opencv-003-图像对象(Mat)创建与赋值

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知识点

  1. C++中Mat对象与创建
  2. Python中Numpy数组对象

代码（c++,python）

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

using namespace std;
using namespace cv;

int main(){
    Mat src = imread("../images/liuyifei_1.png");

    // 通过克隆或复制创建图像对象，m1和src指向不同内存块
    Mat m1 = src.clone();
    Mat m2;
    src.copyTo(m2);

    // 赋值法，m3和src指向同一内存块
    Mat m3 = src;

    // 创建空白图像
    Mat m4 = Mat::zeros(src.size(),src.type());
    Mat m5 = Mat::zeros(Size(512,512),CV_8UC3);
    Mat m6 = Mat::ones(Size(512,512),CV_8UC3);

    // kernel: [0, -1, 0
    //          -1, 5, -1
    //          0, -1, 0]
    Mat kernel = (Mat_<char>(3,3)<<0,-1,0,-1,5,-1,0,-1,0);

    waitKey(0);
    return 0;
}
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import cv2 as cv
import numpy as np

src = cv.imread("../images/liuyifei_1.png")
cv.namedWindow("input", cv.WINDOW_AUTOSIZE)
cv.imshow("input", src)

# 克隆图像
m1 = np.copy(src)

# 赋值
m2 = src
src[100:200,200:300,:] = 255 # 第三维代表图像通道
cv.imshow("m2",m2)

m3 = np.zeros(src.shape, src.dtype)
cv.imshow("m3", m3)

m4 = np.zeros([512,512], np.uint8)
# m4[:,:] =127 try to give gray value 127
cv.imshow("m4", m4)

m5 = np.ones(shape=[512,512,3], dtype=np.uint8)
m5[:,:,0] = 255
cv.imshow("m5", m5)

cv.waitKey(0)
cv.destroyAllWindows()

代码地址

github