OpenCVSharp 4.5 直方图均衡与直方图计算_opencvsharp绘制图像bgr直方图

用OpenCVSharp 4.5 跑一遍 OpenCV官方教程

原官方教程链接：

1. OpenCV: Histogram Equalization
2. OpenCV: Histogram Calculation

核心函数：equalizeHist，split，calcHist，normalize

using System;
using OpenCvSharp;
 
namespace ConsoleApp1
{
    class tutorial20 : ITutorial
    {
        public void Run()
        {
            using (Mat src = new Mat("I:\\csharp\\images\\lena.png", ImreadModes.Color))
            using(Mat dst = new Mat())
            {
                Cv2.CvtColor(src, src, ColorConversionCodes.BGR2GRAY);
                Cv2.EqualizeHist(src, dst);
                using( new Window("Source image", src))
                using (new Window("Equalized Image", dst))                    
                Window.WaitKey();
            }
        }
    }
}

using OpenCvSharp;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
 
namespace ConsoleApp1
{
    class tutorial19 : ITutorial
    {
        public void Run()
        {
 
            using (Mat src = new Mat("I:\\csharp\\images\\lena.png", ImreadModes.Color))
            {
                Mat[] bgr_planes = new Mat[3];
                Cv2.Split(src, out bgr_planes);
 
                int[] histSize = { 256 };
                Rangef[] histRange = { new Rangef(0, 256) }; //the upper boundary is exclusive               
 
                bool uniform = true, accumulate = false;
                Mat b_hist = new Mat();
                Mat g_hist = new Mat();
                Mat r_hist = new Mat();
 
                Cv2.CalcHist(bgr_planes, new int[] { 0 }, null, b_hist, 1, histSize, histRange, uniform, accumulate);
                Cv2.CalcHist(bgr_planes, new int[] { 1 }, null, g_hist, 1, histSize, histRange, uniform, accumulate);
                Cv2.CalcHist(bgr_planes, new int[] { 2 }, null, r_hist, 1, histSize, histRange, uniform, accumulate);
 
                int hist_w = 512, hist_h = 400;
                int bin_w = (int)Math.Round((double)hist_w / histSize[0]);
 
                Mat histImage = new Mat(hist_h, hist_w, MatType.CV_8UC3, new Scalar(0, 0, 0));
 
                Cv2.Normalize(b_hist, b_hist, 0, histImage.Rows, NormTypes.MinMax, -1, null);
                Cv2.Normalize(g_hist, g_hist, 0, histImage.Rows, NormTypes.MinMax, -1, null);
                Cv2.Normalize(r_hist, r_hist, 0, histImage.Rows, NormTypes.MinMax, -1, null);
                for (int i = 1; i < histSize[0]; i++)
                {
                    Cv2.Line(histImage,
                          new Point(bin_w * (i - 1), hist_h - Math.Round(b_hist.At<float>(i - 1))),
                          new Point(bin_w * (i), hist_h - Math.Round(b_hist.At<float>(i))),
                          new Scalar(255, 0, 0),
                          2,
                          LineTypes.Link8,
                          0);
 
                    Cv2.Line(histImage,
                        new Point(bin_w * (i - 1), hist_h - Math.Round(g_hist.At<float>(i - 1))),
                        new Point(bin_w * (i), hist_h - Math.Round(g_hist.At<float>(i))),
                        new Scalar(0, 255, 0),
                        2,
                        LineTypes.Link8,
                        0);
                    Cv2.Line(histImage,
                        new Point(bin_w * (i - 1), hist_h - Math.Round(r_hist.At<float>(i - 1))),
                        new Point(bin_w * (i), hist_h - Math.Round(r_hist.At<float>(i))),
                        new Scalar(0, 0, 255),
                        2,
                        LineTypes.Link8,
                        0);
                }
                using (new Window("Source image", src))
                using (new Window("calcHist Demo", histImage))
                    Window.WaitKey();
            }
        }
    }
}