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
13using namespace cv;
14using namespace std;
15
16/// Global Variables
17Mat src; Mat hsv; Mat hue;
18int bins = 25;
19
20/// Function Headers
21void Hist_and_Backproj(int, void* );
22
23
24/**
25 * @function main
26 */
27int 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 */
58void 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