Question

我想在非黑色像素的cv::mean上执行cv::mat。使用像：

这样的掩码很容易做到

cv::threshold(image, thresholded, 0, 255, cv::THRESH_BINARY);
return cv::mean(image,thresholded);

但是，还有更快的方法吗？也许在OpenCV中有某种内置的颜色屏蔽技术？

P.S。黑色我的意思是(0)或(0,0,0);不应该进行四舍五入。

Answer 1

更紧凑的形式是：

threshold(image, thresholded, 1, 255, cv::THRESH_BINARY);

还要注意：

threshold(image, thresholded, 0, 255, cv::THRESH_BINARY);

您正在屏蔽所有＆gt;的像素1，即0和1都将设置为0.您需要：

With threshold: 6.98269
With > 0 : 4.75043

掩盖所有非零像素。

<强>性能

这种方法也快一点：

#include "opencv2/opencv.hpp"
#include <iostream>
using namespace std;
using namespace cv;

int main(int, char**)
{
    Mat1b img(1000, 1000);
    randu(img, 0, 3);

    {
        double tic = double(getTickCount());
        Mat1b thresholded;
        threshold(img, thresholded, 0, 255, cv::THRESH_BINARY);
        Scalar m = cv::mean(img, thresholded);
        double toc = (double(getTickCount()) - tic) * 1000.0 / getTickFrequency();

        cout << "With threshold: " << toc << endl;
    }

    {
        double tic = double(getTickCount());
        Scalar m = mean(img, img > 0);
        double toc = (double(getTickCount()) - tic) * 1000.0 / getTickFrequency();

        cout << "With > 0 : " << toc << endl;
    }

    getchar();
    return 0;
}

测试代码：

compat-libstdc++-33-3.2.3-69-el6.x86_64.rpm

cv ::非黑色像素的平均值

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