C#：三通道图像直方图

一、程序

        private void uiButton5_Click(object sender, EventArgs e)
        {         
            //1:  计算直方图
            Mat[] mats = Cv2.Split(src_img); //分割图像(把三通道分割为3个单通道)
            Mat hist_B = new Mat();
            Mat hist_G = new Mat();
            Mat hist_R = new Mat();

            int[] channels0 = { 0 };
            int[] channels1 = { 1 };
            int[] channels2 = { 2 };
            int[] histSize = { 256 };

            Rangef[] rangefs = new Rangef[]
            {
                    new Rangef(0, 256),
            };

            Cv2.CalcHist(mats, channels0, new Mat(), hist_B, 1, histSize, rangefs, true, false);
            Cv2.CalcHist(mats, channels1, new Mat(), hist_G, 1, histSize, rangefs, true, false);
            Cv2.CalcHist(mats, channels2, new Mat(), hist_R, 1, histSize, rangefs, true, false);

            int high = 400;
            int width = 512;
            int bin_w = width / 256;//每个bins的宽度  画布的宽度除以bins的个数
            Mat histImage = new Mat(width, high, MatType.CV_8UC3, new Scalar(0, 0, 0)); //定义一个Mat对象，相当于一个画布

            //归一化，像素值有可能数据量很大，压缩一下。是范围在定义画布的范围内。
            Cv2.Normalize(hist_B, hist_B, 0, histImage.Rows, NormTypes.MinMax, -1, null);
            Cv2.Normalize(hist_G, hist_G, 0, histImage.Rows, NormTypes.MinMax, -1, null);
            Cv2.Normalize(hist_R, hist_R, 0, histImage.Rows, NormTypes.MinMax, -1, null);

            //绘制直方图

            for (int i = 1; i < 256; i++)//遍历直方图的级数
            {
                //B 画线，一条线有两个点组成。首先确定每个点的坐标(x,y) .遍历从1开始。0 ~ 1 两个点组成一条线，依次类推。
                Cv2.Line(histImage, new OpenCvSharp.Point(bin_w * (i - 1), high - Math.Round(hist_B.At<float>(i - 1))), new OpenCvSharp.Point(bin_w * (i - 1), high - Math.Round(hist_B.At<float>(i))), new Scalar(255, 0, 0), 1, LineTypes.AntiAlias);

                //G
                Cv2.Line(histImage, new OpenCvSharp.Point(bin_w * (i - 1), high - Math.Round(hist_G.At<float>(i - 1))), new OpenCvSharp.Point(bin_w * (i - 1), high - Math.Round(hist_G.At<float>(i))), new Scalar(0, 255, 0), 1, LineTypes.AntiAlias);

                //R
                Cv2.Line(histImage, new OpenCvSharp.Point(bin_w * (i - 1), high - Math.Round(hist_R.At<float>(i - 1))), new OpenCvSharp.Point(bin_w * (i - 1), high - Math.Round(hist_R.At<float>(i))), new Scalar(0, 0, 255), 1, LineTypes.AntiAlias);

            }
            pictureBox1.Image = histImage.ToBitmap();
        }
    

二、资料

「haixin-561」博客：
https://blog.csdn.net/weixin_41049188/article/details/93401792