opencv-015-绘制几何形状及随机数的生成

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知识点

绘制几何形状

  • 绘制直线
  • 绘制圆
  • 绘制矩形
  • 绘制椭圆
  • 填充几何形状

OpenCV没有专门的填充方法，只是把绘制几何形状时候的线宽thickness参数值设置为负数即表示填充该几何形状或者使用参数CV_FILLED

随机数方法：
RNG 表示OpenCV C++版本中的随机数对象，rng.uniform(a, b)生成[a, b)之间的随机数，包含a，但是不包含b。

np.random.rand() 表示numpy中随机数生成，生成浮点数0～1的随机数, 包含0，不包含1。

代码（c++,python）

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

using namespace std;
using namespace cv;

/*
 * 绘制几何形状及随机数
 */
int main() {
    Mat image = Mat::zeros(Size(512, 512), CV_8UC3);
    Rect rect(100, 100, 200, 200);
    // 绘制
    rectangle(image, rect, Scalar(255, 0, 0), 2, LINE_8, 0);
    circle(image, Point(256, 256), 50, Scalar(0, 255, 0), 2, LINE_8, 0);
    ellipse(image, Point(256, 256), Size(150, 50), 360, 0, 360, Scalar(0, 0, 255), 2, LINE_8, 0);
    imshow("image_draw", image);
    // 填充  thickness=-1 or FILLED
    rectangle(image, rect, Scalar(255, 0, 0), FILLED, LINE_8, 0);
    ellipse(image, Point(256, 256), Size(150, 50), 360, 0, 360, Scalar(0, 0, 255), FILLED, LINE_8, 0);
    circle(image, Point(256, 256), 50, Scalar(0, 255, 0), -1, LINE_8, 0);
    imshow("image_fill", image);

    // 随机数
    RNG rng(0xFFFFFF);
    image.setTo(Scalar(0, 0, 0));
    Mat image_copy = image.clone();
    for (int i = 0; i < 100000; ++i) {
        int x1 = rng.uniform(0, 512);
        int y1 = rng.uniform(0, 512);
        int x2 = rng.uniform(0, 512);
        int y2 = rng.uniform(0, 512);

        int b = rng.uniform(0, 256);
        int g = rng.uniform(0, 256);
        int r = rng.uniform(0, 256);

        rect.x = x1;
        rect.y = y1;
        rect.width = x2 - x1;
        rect.height = y2 - y1;
        // LINE_AA 反锯齿
        line(image, Point(x1, y1), Point(x2, y2), Scalar(b, g, r), 1, LINE_AA, 0);
        rectangle(image_copy, rect, Scalar(b, g, r), 1, LINE_AA, 0);
        imshow("image_line", image);
        imshow("image_rect", image_copy);
        char c = waitKey(20);
        if (c == 27){
            // ESC
            break;
        }
    }

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

image = np.zeros((512, 512, 3), dtype=np.uint8)

cv.rectangle(image, (100, 100), (300, 300), (255, 0, 0), 2, cv.LINE_8, 0)
cv.circle(image, (256, 256), 50, (0, 0, 255), 2, cv.LINE_8, 0)
cv.ellipse(image, (256, 256), (150, 50), 360, 0, 360, (0, 255, 0), 2, cv.LINE_8, 0)
cv.imshow("image", image)
cv.waitKey(0)

for i in range(100000):
    image[:,:,:]= 0
    x1 = np.random.rand() * 512
    y1 = np.random.rand() * 512
    x2 = np.random.rand() * 512
    y2 = np.random.rand() * 512

    b = np.random.randint(0, 256)
    g = np.random.randint(0, 256)
    r = np.random.randint(0, 256)
    # cv.line(image, (np.int(x1), np.int(y1)), (np.int(x2), np.int(y2)), (b, g, r), 4, cv.LINE_8, 0)
    cv.rectangle(image, (np.int(x1), np.int(y1)), (np.int(x2), np.int(y2)), (b, g, r), 1, cv.LINE_8, 0)
    cv.imshow("image", image)
    c = cv.waitKey(20)
    if c == 27:
        break  # ESC不


cv.imshow("image", image)
cv.waitKey(0)
cv.destroyAllWindows()

结果


代码地址

github