1 /**
2 * @file BackProject_Demo1.cpp
3 * @brief Sample code for backproject function usage
4 * @author OpenCV team
5 */
6
7 #include "opencv2/imgproc/imgproc.hpp"
8 #include "opencv2/imgcodecs.hpp"
9 #include "opencv2/highgui/highgui.hpp"
10
11 #include <iostream>
12
13 using namespace cv;
14 using namespace std;
15
16 /// Global Variables
17 Mat src; Mat hsv; Mat hue;
18 int bins = 25;
19
20 /// Function Headers
21 void Hist_and_Backproj(int, void* );
22
23
24 /**
25 * @function main
26 */
main(int,char ** argv)27 int main( int, char** argv )
28 {
29 /// Read the image
30 src = imread( argv[1], 1 );
31 /// Transform it to HSV
32 cvtColor( src, hsv, COLOR_BGR2HSV );
33
34 /// Use only the Hue value
35 hue.create( hsv.size(), hsv.depth() );
36 int ch[] = { 0, 0 };
37 mixChannels( &hsv, 1, &hue, 1, ch, 1 );
38
39 /// Create Trackbar to enter the number of bins
40 const char* window_image = "Source image";
41 namedWindow( window_image, WINDOW_AUTOSIZE );
42 createTrackbar("* Hue bins: ", window_image, &bins, 180, Hist_and_Backproj );
43 Hist_and_Backproj(0, 0);
44
45 /// Show the image
46 imshow( window_image, src );
47
48 /// Wait until user exits the program
49 waitKey(0);
50 return 0;
51 }
52
53
54 /**
55 * @function Hist_and_Backproj
56 * @brief Callback to Trackbar
57 */
Hist_and_Backproj(int,void *)58 void Hist_and_Backproj(int, void* )
59 {
60 MatND hist;
61 int histSize = MAX( bins, 2 );
62 float hue_range[] = { 0, 180 };
63 const float* ranges = { hue_range };
64
65 /// Get the Histogram and normalize it
66 calcHist( &hue, 1, 0, Mat(), hist, 1, &histSize, &ranges, true, false );
67 normalize( hist, hist, 0, 255, NORM_MINMAX, -1, Mat() );
68
69 /// Get Backprojection
70 MatND backproj;
71 calcBackProject( &hue, 1, 0, hist, backproj, &ranges, 1, true );
72
73 /// Draw the backproj
74 imshow( "BackProj", backproj );
75
76 /// Draw the histogram
77 int w = 400; int h = 400;
78 int bin_w = cvRound( (double) w / histSize );
79 Mat histImg = Mat::zeros( w, h, CV_8UC3 );
80
81 for( int i = 0; i < bins; i ++ )
82 { rectangle( histImg, Point( i*bin_w, h ), Point( (i+1)*bin_w, h - cvRound( hist.at<float>(i)*h/255.0 ) ), Scalar( 0, 0, 255 ), -1 ); }
83
84 imshow( "Histogram", histImg );
85
86 }
87