Conversion between mat and two-dimensional array in OpenCV

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In OpenCV, the mat (two-dimensional) corresponds to a two-dimensional array, assigning each pixel value in the mat to a two-dimensional array.

The full code is as follows:

#include <iostream>#include<opencv2/core/core.hpp>#include<opencv2/highgui/highgui.hpp>//contains identifiers such as Imread, imshow, etc.#include"opencv2/imgproc/imgproc.hpp" //includes Cvtcolor, etc.using namespacestd;using namespaceCV;//Test MatvoidMain5 () {//Read in ImageMat mat = Imread ("trabeculae.jpg"); //determine if a picture was read in error    if(Mat.empty ()) {if(!mat.data) {printf ("Oh,no, read the picture file Error ~! \ n"); } cout<<"Error"<<Endl; }      //perform grayscale operation of the imageCvtcolor (Mat, Mat, cv_bgr2gray);    //Getrow and column of Mat    introw =mat.rows; intCol =Mat.cols; cout<<"mat.rows:"<< mat.rows <<Endl; cout<<"Mat.cols:"<< Mat.cols <<Endl; //Create a two-dimensional array dynamically, row row col column    int**la =New int*[row];  for(inti =0; i < row; i + +) {La[i]=New int[col]; }//Loop two-dimensional array and mat, and assign the mat corresponding value to the corresponding value of the two-dimensional array, for(inti =0; i < row; i + +){         for(intj =0; J < Col; J + +) {La[i][j]= mat.at<uchar>(i, j);        }}//Free allocated space for(inti =0; i < row; i + +){        Delete[]la[i]; }    Delete[] La;cout<<Endl; Waitkey (0); System ("Pause");}

Analysis:

1. Read in an image

    // read in image    Mat mat = Imread ("trabeculae.jpg");     // determine if a picture was read in error    if (Mat.empty ())      {           if (!  Mat.data) {             printf ("oh,no, read picture file Error ~! \ n")         ;         } " Error " << Endl;    }  

2. Grayscale operation of the image to convert the mat to two-dimensional.

    //  Image grayscale Operation    Cvtcolor (Mat, Mat, Cv_bgr2gray);

3. MAT has rows and cols properties, rows represents the number of corresponding matrix rows, and cols represents the number of corresponding matrix columns:

    // Save the rows and columns    of the mat int row = mat.rows;     int col = mat.cols;

4. MAT also has a size () method, which can be used to obtain width and Height heights:

    Size s = mat.size ();     int width = s.width;     int height = s.height;

5. The relationship between Rows,cols,width,height:

    "  << s.width << endl;      " "<< s.height << endl;    
    "  << mat.rows << endl;      " "<< mat.cols << Endl;    

6. Printing results:

7. Conclusion:

The 5th and 6th steps are available:

Mat.size (). width == mat.rows;

8. Create a two-dimensional array dynamically:

Example: Create a two-dimensional array of 4 rows and 3 columns, as follows:

{{0, 0, 0}, {0, 0, 0}, {0, 0, 0}, {0, 0, 0}}

That is: {{0, 0, 0},

{0, 0, 0},

{0, 0, 0},

{0, 0, 0}

}

    //Create a two-dimensional array containing 4 one-dimensional arrays, i.e. define 4 rows firstint**array =New int*[4];    //loops a two-dimensional array and creates each element in a two-dimensional array as a one-dimensional array containing 3 elements    //How many rows are allocated first, and how many columns are allocated per row     for(inti =0; I <4; i + +) {Array[i]=New int[3]; }    //Iterate through two-dimensional arrays, rows as outer loops, columns as inner loops, one line through     for(inti =0; I <4; i + +){         for(intj =0; J <3; J + +) {Array[i][j]=0; cout<<" "<<Array[i][j]; } cout<<Endl; }    //The allocated space (memory) needs to be freed when the requested value is used//Free allocated space, one row of deletes     for(inti =0; I <4; i + +){        Delete[]array[i]; }    Delete[] array;

Results:

9. Dynamically create a two-dimensional array with the width and height of the mat image, and the height (row) represents the number of rows, and the width (col) represents the number of columns.

    //Create a two-dimensional array, height (row) row width (col) columnint**la =New int*[height];  for(inti =0; i < height; i + +) {La[i]=New int[Width]; }    //loop assigns the corresponding value in the mat to the LA two-dimensional array for(inti =0; i < row; i + +){         for(intj =0; J < Col; J + +) {La[i][j]= mat.at<uchar>(i, j); //cout << "<< la[i][j";        }        //cout << Endl;    }    //Releasing allocated Space for(inti =0; i < height; i + +){        Delete[]la[i]; }    Delete[] La;

10. Create a two-dimensional array of the row and column sizes of the mat:

When you know the size of a two-dimensional array, you need to assign the values in the two-dimensional array to a mat of the same size, using the mat display.

    // Create a mat variable  height (row) row width (col) column    Mat temp = Mat (height, width, cv_8u, Scalar::all ( 0 ));     // Cyclic Assignment      for (int0; i < height; i + +)        {for ( int  0; J < width; J + +) {            mat.at<uchar> (i, j) = la[i][j];        }    }

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Conversion between mat and two-dimensional array in OpenCV