我想用反函数和很多函数处理图像。为了让代码快速运行，有谁能在 3 种反转方法中建议一种快速方法吗？
double cvInvert(const CvArr* src, CvArr* dst, int method=CV_LU)
- CV_LU 高斯消除并选择最佳主元元素
- CV_SVD 奇异值分解（SVD）方法
- CV_SVD_SYM 对称正定义矩阵的 SVD 方法。
在 OpenCV2.x 中，有一个新的接口，称为Mat::inv(int method)计算矩阵的逆。看参考.
C++: MatExpr Mat::inv(int method=DECOMP_LU) const
参数：
方法 -
Matrix inversion method. Possible values are the following:
DECOMP_LU is the LU decomposition. The matrix must be non-singular.
DECOMP_CHOLESKY is the Cholesky LL^T decomposition for symmetrical positively defined matrices only. This type is about twice faster than LU on big matrices.
DECOMP_SVD is the SVD decomposition. If the matrix is singular or even non-square, the pseudo inversion is computed.
我对每种方法都进行了测试，结果表明 DECOMP_CHOLESKY 对于测试用例来说是最快的，并且 LU 给出了类似的结果。
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <iostream>
int main(void)
{
cv::Mat img1 = cv::imread("2.png");
cv::Mat img2, img3, img;
cv::cvtColor(img1, img2, CV_BGR2GRAY);
img2.convertTo(img3, CV_32FC1);
cv::resize(img3, img, cv::Size(200,200));
double freq = cv::getTickFrequency();
double t1 = 0.0, t2 = 0.0;
t1 = (double)cv::getTickCount();
cv::Mat m4 = img.inv(cv::DECOMP_LU);
t2 = (cv::getTickCount()-t1)/freq;
std::cout << "LU:" << t2 << std::endl;
t1 = (double)cv::getTickCount();
cv::Mat m5 = img.inv(cv::DECOMP_SVD);
t2 = (cv::getTickCount()-t1)/freq;
std::cout << "DECOMP_SVD:" << t2 << std::endl;
t1 = (double)cv::getTickCount();
cv::Mat m6 = img.inv(cv::DECOMP_CHOLESKY);
t2 = (cv::getTickCount()-t1)/freq;
std::cout << "DECOMP_CHOLESKY:" << t2 << std::endl;
cv::waitKey(0);
}
下面是运行结果：
卢:0.000423759
DECOMP_SVD:0.0583525
DECOMP_CHOLESKY：9.3453e-05
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