知识点

1、图像对象的拷贝
学过C++的应该都很清楚，拷贝分为深拷贝和浅拷贝
OpenCV的clone()和copyTo是深拷贝，赋值运算符‘=’是浅拷贝
image.png
头部保存了该图像的宽度和高度还有通道数等信息，数据部分保存了该图像的像素信息

2、图像对象的创建
常用方法有Mat::zeros()和Mat::ones()

C++代码

  1. #include <opencv2/opencv.hpp>
  2. #include <iostream>
  4. using namespace std;
  5. using namespace cv;
  7. void day03() {
  9.     Mat src = imread("E:\\_Image\\OpenCVTest\\girl.jpg");
  11.     if (src.empty()) {
  12.         cout << "could not load image.." << endl;
  13.         return;
  14.     }
  16.     // 创建方法-克隆
  17.     Mat m1 = src.clone();
  19.     // 复制
  20.     Mat m2;
  21.     src.copyTo(m2);
  23.     // 赋值法
  24.     Mat m3 = src;
  26.     // 创建空白图像
  27.     Mat m4 = Mat::zeros(src.size(), src.type());
  28.     Mat m5 = Mat::zeros(Size(512, 512), CV_8UC3);
  29.     Mat m6 = Mat::ones(Size(512, 512), CV_8UC3);
  31.     waitKey(0);
  32. }

Python代码

  1. import cv2 as cv
  2. import numpy as np
  4. # 查看版本
  5. print(cv.__version__)
  7. # 读取图像
  8. src = cv.imread("E:/_Image/OpenCVTest/girl.jpg")
  10. # 深拷贝 克隆图像
  11. m1 = np.copy(src)
  13. # 浅拷贝 赋值
  14. m2 = src
  16. # 修改 src，m2 也会跟着变
  17. src[100:200, 200:300, :] = 255
  19. # 显示
  20. cv.imshow("src", src)
  21. cv.imshow("m1", m1)
  22. cv.imshow("m2", m2)
  24. # 创建图像对象
  25. m3 = np.zeros(src.shape, src.dtype)
  26. cv.imshow("m3", m3)
  28. m4 = np.zeros([512, 512], np.uint8)
  29. m4[:, :] = 127
  30. cv.imshow("m4", m4)
  32. m5 = np.ones(shape=[512, 512, 3], dtype=np.uint8)
  33. m5[:, :, 0] = 255
  34. cv.imshow("m5", m5)
  36. # 等待键盘输入
  37. cv.waitKey()
  39. # 释放内存
  40. cv.destroyAllWindows()

Javascript代码

  1. data() {
  2.   return {
  3.     num2type: {
  4.       1: 'CV_8SC1',
  5.       9: 'CV_8SC2',
  6.       17: 'CV_8SC3',
  7.       25: 'CV_8SC4',
  8.       0: 'CV_8UC1',
  9.       8: 'CV_8UC2',
  10.       16: 'CV_8UC3',
  11.       24: 'CV_8UC4',
  12.       3: 'CV_16SC1',
  13.       11: 'CV_16SC2',
  14.       19: 'CV_16SC3',
  15.       27: 'CV_16SC4',
  16.       2: 'CV_16UC1',
  17.       10: 'CV_16UC2',
  18.       18: 'CV_16UC3',
  19.       26: 'CV_16UC4',
  20.       5: 'CV_32FC1',
  21.       13: 'CV_32FC2',
  22.       21: 'CV_32FC3',
  23.       29: 'CV_32FC4',
  24.       4: 'CV_32SC1',
  25.       12: 'CV_32SC2',
  26.       20: 'CV_32SC3',
  27.       28: 'CV_32SC4',
  28.       6: 'CV_64FC1',
  29.       14: 'CV_64FC2',
  30.       22: 'CV_64FC3',
  31.       30: 'CV_64FC4'
  32.     }
  33.   }
  34. },
  35. methods: {
  36.   onOpenCvReady() {
  37.     if (!this.value) {
  38.       this.$message.error('请选择一种创建类型')
  39.       return
  40.     }
  42.     // 官方文档链接：https://docs.opencv.org/4.5.0/de/d06/tutorial_js_basic_ops.html
  43.     const cv = window.cv
  45.     // 读取图像
  46.     const src = cv.imread('imageSrcRaw')
  48.     // 拷贝 克隆 创建图像
  49.     let dst = null
  50.     switch (this.value) {
  51.       case 1:
  52.         dst = src.clone()
  53.         break
  54.       case 2:
  55.         dst = new cv.Mat()
  56.         src.copyTo(dst)
  57.         break
  58.       case 3:
  59.         dst = new cv.Mat()
  60.         break
  61.       case 4:
  62.         dst = new cv.Mat(512, 512, cv.CV_8UC4)
  63.         break
  64.       case 5:
  65.         dst = new cv.Mat(512, 512, cv.CV_8UC4, [255, 0, 0, 127])
  66.         break
  67.       case 6:
  68.         dst = cv.Mat.zeros(512, 512, cv.CV_8UC4)
  69.         break
  70.       case 7:
  71.         dst = cv.Mat.ones(512, 512, cv.CV_8UC4)
  72.         break
  73.       case 8:
  74.         dst = cv.Mat.eye(512, 512, cv.CV_8UC4)
  75.         break
  76.     }
  78.     // 显示图像
  79.     if (dst) cv.imshow('canvasOutput', dst)
  81.     // 销毁所有 mat 释放内存
  82.     src.delete()
  83.     if (dst) dst.delete()
  84.   },
  85.   showImgInfo() {
  86.     const img = window.cv.imread('imageSrcRaw')
  87.     let content = ''
  88.     content += 'img type: ' + this.num2type[img.type()] + ' '
  89.     content += 'img cols: ' + img.cols + ' '
  90.     content += 'img rows: ' + img.rows + ' '
  91.     content += 'img depth: ' + img.depth() + ' '
  92.     content += 'img channels: ' + img.channels() + ' '
  93.     this.$alert(content, '图像属性', {
  94.       confirmButtonText: '确定'
  95.     })
  96.   }
  97. }