opencv學習筆記24-直方圖反向投影calcBackProject

只用來記錄學習筆記

Mat src, hsv,hue;
const char* window_title = "image";
int bins = 12;
void Hist_And_Backprojection(int, void*);
int main(int argc, char** argv) {
	src = imread("C:/Users/Administrator/Pictures/d503.jpg");
	if (src.empty()) {
		cout << "no image" << endl;
		return -1;
	}
	namedWindow("input", CV_WINDOW_AUTOSIZE);
	namedWindow("Histogram", CV_WINDOW_AUTOSIZE);
	imshow("input", src);

	cvtColor(src, hsv, CV_BGR2HSV);//轉成hsv色彩空間
	hue.create(hsv.size(), hsv.depth());
	
	int nchannels[] = { 0,0 };
	mixChannels(&hsv, 1, &hue, 1, nchannels, 1);//從輸入中拷貝某通道到輸出中特定的通道。
	//&hsv:輸入圖像
	//1：輸入圖像的數量
	//&hue：輸出圖像
	//1：輸出圖像的數量
	//nchannels：輸入矩陣的通道對應輸出矩陣的通道
	//1：參數fromTo中的有幾組輸入輸出通道關係
	createTrackbar("Histogram Bins:","input", &bins, 180, Hist_And_Backprojection);//滑動塊
	Hist_And_Backprojection(0, 0);
	waitKey(0);
	return 0;
}

void Hist_And_Backprojection(int, void*) {
	float range[] = { 0,180 };
	const float *histRanges = { range };//定義值域範圍0-180
	Mat h_hist;
	calcHist(&hue, 1, 0, Mat(), h_hist,1, &bins, &histRanges, true, false);//直方圖計算
	normalize(h_hist, h_hist, 0, 255, NORM_MINMAX,-1,Mat());

	Mat backPrjImage;
	calcBackProject(&hue, 1, 0, h_hist, backPrjImage, &histRanges, 1, true);//計算反向投影圖像
	//&hue:輸入圖像
	//1:圖像數量
	//0：用於計算反向投影的通道列表
	//h_hist：輸入的直方圖
	//backPrjImage：目標反向投影輸出圖像，是一個單通道圖像，與原圖像有相同的尺寸和深度
	//&histRanges：直方圖中每個維度bin的取值範圍
	//1：可選輸出反向投影的比例因子
	//true：直方圖是否均勻分佈(uniform)的標識符，有默認值true
	imshow(window_title, backPrjImage);

	int hist_h = 400;
	int hist_w = 400;
	Mat histImage(hist_w, hist_h, CV_8UC3, Scalar(0, 0, 0));
	int bin_w = (hist_w / bins);//400/bins;
	for (int i = 1; i < bins; i++) {
		rectangle(histImage, Point((i - 1)*bin_w, hist_h - cvRound(h_hist.at<float>(i - 1) * (400 / 255))),
			//Point((i)*bin_w, cvRound(hist_h - h_hist.at<float>(i) * (400 / 255)))
			Point(i*bin_w, hist_h)
			,Scalar(0,0,255),-1);//劃矩形
	}
	imshow("Histogram", histImage);
	return;
}

bins = 12：

bin=85：