OpenCVSharp 4.5 图像矩

最新推荐文章于 2023-11-30 10:16:44 发布

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本文介绍如何使用 OpenCVSharp4.5 实现图像轮廓的检测与分析，包括轮廓面积、周长等关键信息的计算，并通过 C# 代码实现 OpenCV 官方教程中的图像矩及轮廓属性的提取。

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用OpenCVSharp 4.5 跑一遍 OpenCV官方教程

原官方教程链接：OpenCV: Image Moments

核心函数：

using System;
using OpenCvSharp;

namespace ConsoleApp1
{
    class tutorial27 : ITutorial
    {
        static Mat src_gray = new Mat();
        static int thresh = 100;
        static RNG rng = new RNG(12345);

        public void Run()
        {
            Mat src = Cv2.ImRead("I:\\csharp\\images\\cartoons.jpg");
            if (src.Empty())
            {
                Console.WriteLine("Could not open or find the image!");
                return;
            }
            Cv2.CvtColor(src, src_gray, ColorConversionCodes.BGR2GRAY);
            Cv2.Blur(src_gray, src_gray, new Size(5, 5));
            Cv2.NamedWindow("Source", WindowFlags.AutoSize);
            Cv2.ImShow("Source", src);
            Cv2.CreateTrackbar("Canny thresh:", "Source", ref thresh, 255, thresh_callback);
            thresh_callback(0, IntPtr.Zero);
            Cv2.WaitKey();
        }

        private void thresh_callback(int pos, IntPtr userData)
        {
            Mat canny_output = new Mat();
            Cv2.Canny(src_gray, canny_output, thresh, thresh * 2);
            Point[][] contours;
            HierarchyIndex[] hIndex;
            Cv2.FindContours(canny_output, out contours, out hIndex, RetrievalModes.Tree, ContourApproximationModes.ApproxSimple);

            Moments[] mu = new Moments[contours.Length];

            for (int i = 0; i < contours.Length; i++)
            {
                mu[i] = Cv2.Moments(contours[i]);
            }

            Point2f[] mc = new Point2f[contours.Length];

            for (int i = 0; i < contours.Length; i++)
            {
                //add 1e-5 to avoid division by zero
                mc[i] = new Point2f((float)(mu[i].M10 / (mu[i].M00 + 1e-5)),
                                     (float)(mu[i].M01 / (mu[i].M00 + 1e-5)));
                Console.WriteLine("mc[{0}]={1}", i, mc[i]);
            }

            Mat drawing = Mat.Zeros(canny_output.Size(), MatType.CV_8UC3);
            for (int i = 0; i < contours.Length; i++)
            {
                Scalar color = new Scalar(rng.Uniform(0, 256), rng.Uniform(0, 256), rng.Uniform(0, 256));
                Cv2.DrawContours(drawing, contours, (int)i, color, 1);
                Cv2.Circle(drawing, (Point)mc[i], 4, color, 1);
            }
            Cv2.ImShow("Contours", drawing);
            Console.WriteLine("\t Info: Area and Contour Length");
            for (int i = 0; i < contours.Length; i++)
            {
                Console.WriteLine(" * Contour[{0}] - Area (M_00) = {1} - Area OpenCV:{2:0.###} - Length:{3:0.###} ",
                    i, mu[i].M00,
                    Cv2.ContourArea(contours[i]),
                    Cv2.ArcLength(contours[i], true)
                    );
            }
        }
    }
}