有人可以帮我把这个命令翻译成 C++(OpenCV)吗?
[h t] = hist(img(roi_mask>0),2048);
对于直方图,您可以使用以下类(类来自 openCV 2 Computer Vision 书):
class Histogram1D{
private:
int histSize[1];
float hranges[2];
const float* ranges[1];
int channels[1];
cv::MatND hist;
public:
Histogram1D()
{
histSize[0] = 2048;
hranges[0]=0.0;
hranges[1] = 255.0;
ranges[0] = hranges;
channels[0] = 0;//by default, we look at channel 0
}
Histogram1D(float minval,float maxval)
{
histSize[0] = 2048;
hranges[0]=minval;
hranges[1] = maxval;
ranges[0] = hranges;
channels[0] = 0;//by default, we look at channel 0
}
//Hier wird die cv funktion zum bestimmen vom Histogramm gestartet
cv::MatND calcHistogram(const cv::Mat &image){
//compute histogram
cv::calcHist(&image,
1, //histogram from 1 image only
channels, //the channel used
cv::Mat(), //no mask is used
hist, //the resulting histogram
1, //it is a 1D histogram
histSize, //number of bins
ranges //pixel value range
);
return hist;
}
cv::MatND getHistogram(){
return hist;
}
cv::Mat getHistogramImage(){
//compute histogram first
cv::MatND hist= getHistogram();
//get min and max bin values
double maxVal=0;
double minVal=0;
cv::minMaxLoc(hist, &minVal, &maxVal, 0,0);
//Image on which to display histogram
cv::Mat histImg(histSize[0]+40, histSize[0],CV_8U,cv::Scalar(255));
//set highest point at 90% of nbins
int hpt = static_cast<int>(0.9*histSize[0]);
//Draw a vertical line for each bin
for (int h=0;h<histSize[0];h++)
{
float binVal=hist.at<float>(h);
int intensity = static_cast<int>(binVal*hpt/maxVal);
//This function draws a line between 2 points
cv::line(histImg,cv::Point(h,histSize[0]),cv::Point(h,histSize[0]-intensity),cv::Scalar::all(0));
}
//min und max val im Histogramm angeben
char maxValStr[10],minValStr[10];
sprintf (maxValStr, "%d",static_cast<int>(hranges[1]));
sprintf (minValStr, "%d",static_cast<int>(hranges[0]));
int fontFace = cv::FONT_HERSHEY_SCRIPT_SIMPLEX;
double fontScale = 0.3;
int thickness = 1;
cv::Point textOrgmax(histSize[0]-40, histSize[0]+20),textOrgmin(5, histSize[0]+20);
cv::putText(histImg, maxValStr, textOrgmax, fontFace, fontScale, cv::Scalar::all(0), thickness,8);
cv::putText(histImg, minValStr, textOrgmin, fontFace, fontScale, cv::Scalar::all(0), thickness,8);
return histImg;
}
};
这里是你如何使用它:
// Transform it into the C++ cv::Mat format
cv::Mat image(imagesource);
// Setup a rectangle to define your region of interest
cv::Rect myROI(10, 10, 100, 100);
// Crop the full image to that image contained by the rectangle myROI
// Note that this doesn't copy the data
cv::Mat croppedImage = image(myROI);
cv::Mat tmp = croppedImage .clone();//clone image
double min =0,max = 0;
cv::minMaxLoc(tmp,&min,&max);
cv::namedWindow("Histogram",CV_WINDOW_AUTOSIZE);
Histogram1D h(min,max);
h.calcHistogram(tmp);
cv::imshow("Histogram",h.getHistogramImage());
因此,您需要蒙版图像上的 2048 个 bin 的直方图,返回一个包含计数和 bin 值的矩阵。
我想您可以使用 calcHist,甚至可以自定义它或构建您自己的函数。您需要知道如何访问数组元素、数组操作和直方图的基本理论。
您的问题隐藏了许多问题,因为 Matlab 级别更高。分解你的问题,你会发现所有的答案都散落在论坛里......