opencv reshape函數說明

轉自http://blog.csdn.net/yang6464158/article/details/20129991

reshape有兩個參數：

其中，參數：cn為新的通道數，如果cn = 0，表示通道數不會改變。

參數rows為新的行數，如果rows = 0，表示行數不會改變。

注意：新的行*列必須與原來的行*列相等。就是說，如果原來是5行3列，新的行和列可以是1行15列，3行5列，5行3列，15行1列。僅此幾種，否則會報錯。

具體調用也很簡單，代碼如下所示：

 

#include <iostream>
#include <opencv/cv.h>
#include <opencv/highgui.h>
int main()
{
    cv::Mat testMat = cv::Mat::zeros ( 5, 3, CV_8UC3 );
    std::cout << "size of testMat: " << testMat.rows << " x " << testMat.cols << std::endl;
    std::cout<<"testMat = "<<testMat<<std::endl;
    cv::Mat result = testMat.reshape ( 0, 3 );
    std::cout << " size of original testMat: " << testMat.rows << " x " << testMat.cols << std::endl;
    std::cout << " size of reshaped testMat: " << result.rows << " x " << result.cols << std::endl;
    std::cout << "result = " << result << std::endl;
    cv::waitKey(0);
    system("pause");
    return 0;
}

結果如下：

 

 

比如說：下面的情況就會報錯：

 

#include <iostream>
#include <opencv/cv.h>
#include <opencv/highgui.h>
int main()
{
    cv::Mat testMat = cv::Mat::ones ( 5, 3, CV_8UC3 );
    std::cout << "size of testMat: " << testMat.rows << " x " << testMat.cols << std::endl;
    std::cout<<"testMat = "<<testMat<<std::endl;
    cv::Mat result = testMat.reshape ( 0, 6 );
    std::cout << " size of original testMat: " << testMat.rows << " x " << testMat.cols << std::endl;
    std::cout << " size of reshaped testMat: " << result.rows << " x " << result.cols << std::endl;
    std::cout << "result = " << result << std::endl;
    cv::waitKey(0);
    system("pause");
    return 0;
}

因為行和列的乘積不相等

 

結果如下：

我們在使用reshape的時候一定不能用定義的Mat類型賦給原來的類型，必須重新定義一個新類。

可以這樣：

 

unsigned char v11[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 };
cv::Mat A = cv::Mat(3, 4, CV_8U, v11);
cv::Mat B = A.reshape(1, 12);

但不能這樣：

 

 

cv::Mat testMat = cv::Mat::zeros ( 5, 3, CV_8UC3 );
std::cout << "size of testMat: " << testMat.rows << " x " << testMat.cols << std::endl;

testMat.reshape ( 0, 1 );
std::cout << " size of reshaped testMat: " << testMat.rows << " x " << testMat.cols << std::endl;