C# - Opencv应用（3） 之矩阵Mat使用[图像截取粘贴、ROI操作、位运算、数学计算]

• 图像读取，大小、截取、位运算
• 图像ROI操作：粘贴+赋值、滤波
• 图像数学计算
• 部分结果如下：
  

1.图像读取，大小、截取、位运算

        //图像显示
        private static void showImg(string w_name,Mat img,int flg=0)
        {
            Cv2.NamedWindow(w_name, 0);
            Cv2.ImShow(w_name, img);
            Cv2.WaitKey(flg);
        }

        private static void SubMat()
        {
            var src = Cv2.ImRead("./images/Lenna.png");
            if(src.Empty())
            {
                Console.WriteLine("请检查图像输入！\n");
            }
            else
            {
                Console.WriteLine("读取图像大小：[" + src.Rows + "," + src.Cols + "]");
            }
            showImg("src", src);

            // Assign small image to mat
            var small = new Mat();
            Cv2.Resize(src, small, new Size(100, 100));
            src[10, 110, 10, 110] = small;
            showImg("src1", src);
            src[370, 470, 400, 500] = small.T();
            showImg("src2", src);
            // ↑ This is same as the following:
            //small.T().CopyTo(src[370, 470, 400, 500]);

            // Get partial mat (similar to cvSetImageROI)
            Mat part = src[200, 400, 200, 360];
            // Invert partial pixel values
            Cv2.BitwiseNot(part, part);

            // Fill the region (50..100, 100..150) with color (128, 0, 0)
            part = src.SubMat(50, 100, 400, 450);
            part.SetTo(128);

            using (new Window("SubMat", src))
            {
                Cv2.WaitKey();
            }

            part.Dispose();
        }

2. 图像ROI操作：粘贴+赋值、滤波

• 针对不同范围的区域即ROI进行不同的操作，根本上是像素/灰度值的改变

        //图像行列中的某些范围做操作
        private void RowColRangeOperation()
        {
            using var src = Cv2.ImRead(ImagePath.Lenna);

            Cv2.GaussianBlur(
                src.RowRange(100, 200),
                src.RowRange(200, 300),
                new Size(7, 7), 20);

            Cv2.GaussianBlur(
                src.ColRange(200, 300),
                src.ColRange(100, 200),
                new Size(7, 7), 20);

            using (new Window("RowColRangeOperation", src))
            {
                Cv2.WaitKey();
            }
        }

        /// <summary>
        /// Submatrix expression operations
        /// </summary>
        private void RowColOperation()
        {
            using var src = Cv2.ImRead(ImagePath.Lenna);

            var rand = new Random();
            for (int i = 0; i < 200; i++)
            {
                int c1 = rand.Next(100, 400);
                int c2 = rand.Next(100, 400);
                using Mat temp = src.Row(c1).Clone();
                src.Row(c2).CopyTo(src.Row(c1));
                temp.CopyTo(src.Row(c2));
            }

            ((Mat)~src.ColRange(450, 500)).CopyTo(src.ColRange(0, 50));

            src.RowRange(450, 460).SetTo(new Scalar(0, 0, 255));

            using (new Window("RowColOperation", src))
            {
                Cv2.WaitKey();
            }
        }

3.图像数学计算

• 通过矩阵进行普通与归一化矩阵计算

//数学计算
        /// <summary>
        /// Solve equation AX = Y
        /// </summary>
        private static void ByMat()
        {
            // x + y = 10
            // 2x + 3y = 26
            // (x=4, y=6)

            double[,] av = {{1, 1},
                          {2, 3}};
            double[] yv = { 10, 26 };

            var a = new Mat(2, 2, MatType.CV_64FC1, av);
            var y = new Mat(2, 1, MatType.CV_64FC1, yv);
            var x = new Mat();

            Cv2.Solve(a, y, x, DecompTypes.LU);

            Console.WriteLine("ByMat:");
            Console.WriteLine("X1 = {0}, X2 = {1}", x.At<double>(0), x.At<double>(1));
        }

        /// <summary>
        /// Solve equation AX = Y
        /// </summary>
        private static void ByNormalArray()
        {
            // x + y = 10
            // 2x + 3y = 26
            // (x=4, y=6)

            double[,] a = {{1, 1},
                          {2, 3}};

            double[] y = { 10, 26 };

            var x = new System.Collections.Generic.List<double>();

            Cv2.Solve(
                InputArray.Create(a), InputArray.Create(y),
                OutputArray.Create(x),
                DecompTypes.LU);

            Console.WriteLine("ByNormalArray:");
            Console.WriteLine("X1 = {0}, X2 = {1}", x[0], x[1]);
        }

完整代码

• 主要代码结构如下：

using System;
using OpenCvSharp;

namespace SamplesCore
{
    /// <summary>
    /// 
    /// </summary>
    class MatOperations
    {
        static void Main(string[] args)
        {
            ByMat();
            ByNormalArray();

            SubMat();
            RowColRangeOperation();
            RowColOperation();

            return;
        }
        
        //函数定义。。。。。。
    }
}