的calcHist

Question

我的目标不当使用是产生的灰度图像的直方图。我使用的代码是：

Mat img = imread("leeds-castle.jpg",IMREAD_GRAYSCALE); 
Mat hst; 
int hstsize = 256; 
float ranges[] = { 0,256 }; 
float *hstrange = { ranges }; 
calcHist(img, 1,0, Mat(), hst, 1, &hstsize,&hstrange,true,false); 
int hst_w = 512, hst_h = 400; 
int bin_w = cvRound((double)hst_w/256); 
Mat histimg(hst_w, hst_h, CV_8U); 
normalize(hst, hst, 0, histimg.rows, NORM_MINMAX, -1, Mat()); 
for (int i = 1; i < 256; i++) 
{ 
    line(histimg, Point(bin_w*(i - 1), hst_h - cvRound(hst.at<float>(i - 1))), Point(bin_w*i, hst_h - cvRound(hst.at<float>(i))), 2, 8, 0); 
} 
imshow("Histogram", histimg); 

的唯一错误是calcHist()函数的用法。它有什么问题吗？

Answer 1

见上面calcHist的意见，以确定正确的用法：

// original image 
Mat img = imread("leeds-castle.jpg",IMREAD_GRAYSCALE); 
// NOTE: check if img.channels is equal to 1 

// histogram 
Mat hst; 

// number of bins 
int hstsize = 256; 
float ranges[] = { 0,256 }; 
float *hstrange = { ranges }; 

// parameters for histogram calculation 
bool uniform = true; 
bool accumulate = false; 

// calculate histogram 
// the '&' was missing here 
calcHist(&img, 1,0, Mat(), hst, 1, &hstsize,&hstrange,true,false);