使用Opencv获取多张图片的标准偏差

Question

我正在尝试使用OpenCV获得多张图片的标准偏差，我所做的是：

#包括#包括#包括

 using namespace std;
  using namespace cv;
 int main(){
cv::Mat frame,frame32f;
char filename[40];
cv::Mat mean;
const int count =134;
const int width  = 1920;
const int height = 1080;
cv::Mat resultframe = cv::Mat::zeros(height,width,CV_32FC3);
cv::Mat deviationframe = cv::Mat ::zeros(height,width,CV_32FC3);
cv::Mat temp = cv::Mat ::zeros(height,width,CV_32FC3);
for(int i = 1 ; i<= count; i++){
//int i = 3;
sprintf(filename,"d:\BMdvideos\images\image%d.tiff",i);
frame = imread(filename,CV_LOAD_IMAGE_COLOR);
frame.convertTo(frame32f,CV_32FC3 );
resultframe +=frame32f;
frame.release();
}
resultframe *= (1.0/count);
for(int j =1; j<count; j++){
    sprintf(filename,"d:\BMdvideos\images\image%d.tiff",j);
    frame = imread(filename,CV_LOAD_IMAGE_COLOR);
    frame.convertTo(frame32f,CV_32FC3);
    temp =(frame32f - resultframe);
    deviationframe+= temp.mul(temp);
    //temp.release();
}
imshow("devi",deviationframe);  // works
deviationframe *= 1.0/(count -1);
imshow("devi2",deviationframe); // works
cv::sqrt(deviationframe,deviationframe);
resultframe *= 1.0/255.0;
imshow("devi3",deviationframe);// works
deviationframe *= 1.0/255.0;
imshow("mean ",resultframe);
imshow("deviation frame ",deviationframe);// BLACK FRAME !!!!!!!!!!!!!!!!!!!
    waitKey(0);
return 0;

}

当我看到我得到的结果时，"平均值"是正确的，但标准偏差是错误的。知道我做错了什么吗，提前感谢的帮助

Answer 1

您没有累积差分平方图像的结果来计算标准偏差。当前代码的结果是，只有最后一个图像被平方并除以图像总数。之前的所有计算都无效。

此外，除以255仅用于图像的可视化，而不用于实际计算。在计算标准偏差之前，你要除以255，这会使你的结果不正确。

修改您的代码如下：

.
.
.
resultframe *= (1.0/count);
cv::Mat deviationResult = cv::Mat::zeros(height,width,CV_32FC3);
for(int j =1; j< count; j++)
{
    sprintf(filename,"d:\BMdvideos\images\image%d.tiff",j);
    frame = imread(filename,CV_LOAD_IMAGE_COLOR);
    frame.convertTo(frame32f,CV_32FC3);
    deviationframe =(frame32f - resultframe);
    deviationResult += deviationframe.mul(deviationframe);
}
resultframe *= (1.0/255.0);
deviationResult = deviationResult /(count -1 );
cv::sqrt(deviationResult ,deviationResult );
deviationResult *= (1.0/255.0);
imshow("mean ",resultframe);
imshow("deviation frame ",deviationResult);
waitKey(0);
return 0;

Answer 2

在@sgar91的帮助下，这是最后一段代码，我希望它能帮助任何

 #include <opencv2corecore.hpp>
#include <opencv2highguihighgui.hpp>
#include <opencv2opencv.hpp>
#include <stdlib.h>
using namespace std;
using namespace cv;
 int main(){
cv::Mat frame,frame32f;
char filename[40];
cv::Mat mean;
const int count =134;
const int width  = 1920;
const int height = 1080;
cv::Mat resultframe = cv::Mat::zeros(height,width,CV_32FC3);
cv::Mat deviationframe = cv::Mat ::zeros(height,width,CV_32FC3);
cv::Mat temp = cv::Mat ::zeros(height,width,CV_32FC3);
for(int i = 1 ; i<= count; i++){
    sprintf(filename,"d:\BMdvideos\images\image%d.tiff",i);
    frame = imread(filename,CV_LOAD_IMAGE_COLOR);
    frame.convertTo(frame32f,CV_32FC3 );
    resultframe +=frame32f;
    frame.release();
}
resultframe *= (1.0/count);
for(int j =1; j<count; j++){
    sprintf(filename,"d:\BMdvideos\images\image%d.tiff",j);
    frame = imread(filename,CV_LOAD_IMAGE_COLOR);
    frame.convertTo(frame32f,CV_32FC3);
    temp =(frame32f - resultframe);
    deviationframe+= temp.mul(temp);
    //temp.release();
}
deviationframe *= 1.0/(count -1);
deviationframe= deviationframe/255;
cv::sqrt(deviationframe,deviationframe);
resultframe *= 1.0/255.0;
imshow("mean ",resultframe);
imshow("deviation frame ",deviationframe);
waitKey(0);
return 0;
 }