灰度直方图

cv::Mat opencvTool::calculateHistogram(const cv::Mat& image)
{// 如果输入图像尚未处于灰度级，请将其转换为灰度级cv::Mat grayscale_image;if (image.channels() > 1){cv::cvtColor(image, grayscale_image, cv::COLOR_BGR2GRAY);}else{grayscale_image = image.clone();}// 计算直方图cv::Mat hist;int histSize = 256;float range[] = { 0, 256 };const float* histRange = { range };bool uniform = true, accumulate = false;cv::calcHist(&grayscale_image, 1, nullptr, cv::Mat(), hist, 1, &histSize, &histRange, uniform, accumulate);// 绘制直方图int hist_w = 512, hist_h = 400;int bin_w = cvRound((double)hist_w / histSize);cv::Mat histImage(hist_h, hist_w, CV_8UC3, cv::Scalar(255, 255, 255));cv::normalize(hist, hist, 0, histImage.rows, cv::NORM_MINMAX, -1, cv::Mat());for (int i = 1; i < histSize; i++){cv::line(histImage, cv::Point(bin_w * (i - 1), hist_h - cvRound(hist.at<float>(i - 1))),cv::Point(bin_w * (i), hist_h - cvRound(hist.at<float>(i))),cv::Scalar(0, 0, 0), 2, 8, 0);}return histImage;
}