我想处理具有反函数和许多函数的图像。对于快速运行的代码,可以在3种反演方法中建议快速方法吗?
double cvInvert(const CvArr* src, CvArr* dst, int method=CV_LU)
答案 0 :(得分:7)
在OpenCV2.x中,有一个名为Mat::inv(int method)
的新接口来计算矩阵的逆矩阵。请参阅reference。
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.
我对每个方法进行了测试,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);
}
这是正在运行的结果:
LU:0.000423759
DECOMP_SVD:0.0583525
DECOMP_CHOLESKY:9.3453e-05