opencv videocapture lag

asked 2016-01-14 05:57:21 -0500

grisi gravatar image

hi everybody,

we have implemented a colour detection, as can be seen in the attached code. the problem is, that when moving the object, that shall be detected, reveils a delay of about 3 seconds. we assume the problem is the buffer size of the processed frames is too big.

a solution might be to process only every n-th frame, instead of each. unfortunately I can't access the lab these days, so if someone has further ideas I'm very thankful for every input.

#include <cv.h>
#include <highgui.h>
#include <iostream>
#include "opencv2/imgproc/imgproc.hpp"
#include <math.h>

using namespace cv;

//initial min and max HSV filter values.
//these will be changed using trackbars
int H_MIN = 167;
int H_MAX = 195;
int S_MIN = 121;
int S_MAX = 256;
int V_MIN = 0;
int V_MAX = 256;

//default capture width and height
const int FRAME_WIDTH = 640;
const int FRAME_HEIGHT = 480;
//max number of objects to be detected in frame
const int MAX_NUM_OBJECTS=50;
//minimum and maximum object area
const int MIN_OBJECT_AREA = 5*5;
//names that will appear at the top of each window
const string windowName = "Original Image";
const string windowName1 = "HSV Image";
const string windowName2 = "Thresholded Image";
const string windowName3 = "After Morphological Operations";
const string trackbarWindowName = "Trackbars";

// Marker Jump
#define  ArraySize 5
int CoordinatesHistory[ArraySize][2];
int CurrentCoordinates[1][2];

int distance = 0;
int radius = 0;
int history = 0;

void on_trackbar( int, void* )
{//This function gets called whenever a
    // trackbar position is changed


string intToString(int number){
    std::stringstream ss;
    ss << number;
    return ss.str();
void createTrackbars(){
    //create window for trackbars
     createTrackbar( "H_MIN", trackbarWindowName, &H_MIN, H_MAX, on_trackbar );
    createTrackbar( "H_MAX", trackbarWindowName, &H_MAX, H_MAX, on_trackbar );
    createTrackbar( "S_MIN", trackbarWindowName, &S_MIN, S_MAX, on_trackbar );
    createTrackbar( "S_MAX", trackbarWindowName, &S_MAX, S_MAX, on_trackbar );
    createTrackbar( "V_MIN", trackbarWindowName, &V_MIN, V_MAX, on_trackbar );
    createTrackbar( "V_MAX", trackbarWindowName, &V_MAX, V_MAX, on_trackbar );
void drawObject(int x, int y,Mat &frame){

    //use some of the openCV drawing functions to draw crosshairs
    //on your tracked image!

    //UPDATE:JUNE 18TH, 2013
    //added 'if' and 'else' statements to prevent
    //memory errors from writing off the screen (ie. (-25,-25) is not within the window!)

    else line(frame,Point(x,y),Point(x,0),Scalar(0,255,0),2);
    else line(frame,Point(x,y),Point(x,FRAME_HEIGHT),Scalar(0,255,0),2);
    else line(frame,Point(x,y),Point(0,y),Scalar(0,255,0),2);
    else line(frame,Point(x,y),Point(FRAME_WIDTH,y),Scalar(0,255,0),2);

    putText(frame,intToString(x)+","+intToString(y),Point(x,y+30),1,1,Scalar(0 ...
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