I have written the following program to detect a circle in real time. But it doesn't work.
The compiler doesn't show any error but the problem is that the program doesn't even detect a circle. How can I fix it?
here is my code
using namespace cv;
int main()
{
VideoCapture cap(0);
namedWindow("main",CV_WINDOW_AUTOSIZE);
namedWindow("blur",CV_WINDOW_AUTOSIZE);
Mat img;
Mat img2;
int c;
float radius;
while(1)
{
cap>>img;
imshow("main",img);
cvtColor(img,img2,CV_BGR2GRAY);
GaussianBlur(img2,img2,Size(9,9),2,2);
imshow("blur",img2);
vector <Vec3f> circles;
HoughCircles(img2,circles,CV_HOUGH_GRADIENT,1,img2.rows/8,200,100,0,0);
for(size_t i=0;i<circles.size();i++)
{
Point center(cvRound(circles[i][0]),cvRound(circles[i][1]));
radius = cvRound(circles[i][2]);
circle(img,center,3,Scalar(0,255,0),-1,8,0);
circle(img,center,radius,Scalar(0,0,255),3,8,0);
}
c = waitKey(33);
if(c==27)
break;
}
destroyAllWindows();
return 0;
}
I checked your program, it seems you just forgot to visualize it using imshow() after the detection. You only drew the image before the detection, in this way, you were not able to see the circles (maybe this mistakenly make you think there is no circles detected) even it did detect some circles.
Try to add
imshow("main", img);
right before c = waitKey(33);.
You will see the circles if it does detect some circles.
Edit: to answer your comment for real time circle detection:
Do it in a while loop style will make it work for video frames. However, whether it is real time or not depends on how fast HoughCircles() will work and also other stuff inside the loop despite you setup the proper time for waitKey().
Related
So, here is my situation. I have created a object detection program which is based on color object detection. My program detects the color red and it works perfectly. But here is the problems i am facing:-
Whenever there are more than one red object in the surrounding, my program detects them and it cannot really track one object at that time(i.e it tracks other red objects of various sizes in the background. It shows me the error that "too much noise in the background". As you can see in the "threshold image" attached, it detects the round object (which is my tracking object) and my cap which is red in color. I want my program to detect only my tracking object("which is a round shaped coke cap"). How can i achieve that? Please help me out. I have my engineering design contest in few days and i have to demo my program infront of my lecturers. My program should only be able to detect and track the object which i want. Thanks
My code for the objectdetection program is a little long. So, i am hereby explaining the code as follows- I captured a frame from the webcam frame-converted it to HSV- used HSV Inrange filter to filter out the other colors but red- applied morphological operations on the filtered image. This all goes in my main function
I am using a frame resolution of 1280*720 for my webcam frame. It kind of slows down my program but it was a trade off which i had to do for performing gesture controlled operations. Anyways here is my drawobjectfunction and trackfilteredobjectfunction.
int H_MIN = 0;
int H_MAX = 256;
int S_MIN = 0;
int S_MAX = 256;
int V_MIN = 0;
int V_MAX = 256;
//default capture width and height
const int FRAME_WIDTH = 1280;
const int FRAME_HEIGHT = 720;
//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 = 20*20;
const int MAX_OBJECT_AREA = FRAME_HEIGHT*FRAME_WIDTH/1.5;
void drawObject(int x, int y,Mat &frame){
circle(frame,Point(x,y),20,Scalar(0,255,0),2);
if(y-25>0)
line(frame,Point(x,y),Point(x,y-25),Scalar(0,255,0),2);
else line(frame,Point(x,y),Point(x,0),Scalar(0,255,0),2);
if(y+25<FRAME_HEIGHT)
line(frame,Point(x,y),Point(x,y+25),Scalar(0,255,0),2);
else line(frame,Point(x,y),Point(x,FRAME_HEIGHT),Scalar(0,255,0),2);
if(x-25>0)
line(frame,Point(x,y),Point(x-25,y),Scalar(0,255,0),2);
else line(frame,Point(x,y),Point(0,y),Scalar(0,255,0),2);
if(x+25<FRAME_WIDTH)
line(frame,Point(x,y),Point(x+25,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(0,255,0),2);
}
void trackFilteredObject(int &x, int &y, Mat threshold, Mat &cameraFeed){
Mat temp;
threshold.copyTo(temp);
//these two vectors needed for output of findContours
vector< vector<Point> > contours;
vector<Vec4i> hierarchy;
//find contours of filtered image using openCV findContours function
findContours(temp,contours,hierarchy,CV_RETR_CCOMP,CV_CHAIN_APPROX_SIMPLE );
//use moments method to find our filtered object
double refArea = 0;
bool objectFound = false;
if (hierarchy.size() > 0) {
int numObjects = hierarchy.size();
//if number of objects greater than MAX_NUM_OBJECTS we have a noisy filter
if(numObjects<MAX_NUM_OBJECTS){
for (int index = 0; index >= 0; index = hierarchy[index][0]) {
Moments moment = moments((cv::Mat)contours[index]);
double area = moment.m00;
//if the area is less than 20 px by 20px then it is probably just noise
//if the area is the same as the 3/2 of the image size, probably just a bad filter
//we only want the object with the largest area so we safe a reference area each
//iteration and compare it to the area in the next iteration.
if(area>MIN_OBJECT_AREA && area<MAX_OBJECT_AREA && area>refArea){
x = moment.m10/area;
y = moment.m01/area;
objectFound = true;
refArea = area;
}else objectFound = false;
}
//let user know you found an object
if(objectFound ==true){
putText(cameraFeed,"Tracking Object",Point(0,50),2,1,Scalar(0,255,0),2);
//draw object location on screen
drawObject(x,y,cameraFeed);}
}else putText(cameraFeed,"TOO MUCH NOISE! ADJUST FILTER",Point(0,50),1,2,Scalar(0,0,255),2);
}
}
Here is the link of the image; as you can see it also detects the red hat in the background along with the red cap of the coke bottle.
My observations:- Here is what i think, to achieve my desired goal of not detecting objects of unknown sizes of red color. I think i have to edit the value of maximum object area which i declared in the above program as (const int MAX_OBJECT_AREA = FRAME_HEIGHT*FRAME_WIDTH/1.5;). I think i have to change this value, that might eliminate the detection of bigger continous red pictures. But also, there is another problem some objects are not completely red in color and they have patches of red and other colors. So, if the detected area is within the range specfied in my program then my program detects those red patches too. What i mean to say is i was wearing a tshirt which has mixed colors and when i tested my program by wearing that tshirt, my program was able to detect the red color out of the other colors. Now, how do i solve this issue?
I think you can try out the following procedure:
obtain a circular kernel having roughly the same area as your object of interest. You can do it like: Mat kernel = getStructuringElement(MORPH_ELLIPSE, Size(d, d));
where d is the diameter of the disk.
perform normalized-cross-correlation or convolution of the filtered regions image with this kernel (I think normalized-cross-correlation would be better. And add an empty boarder around the kernel).
the peak of the resulting image should give you the location of the circular region in your filtered image (if you are using normalized-cross-correlation, you'll have to add the shift).
To speed things up, you can perform this at a reduced resolution.
You can filter out non-circular shapes by detecting circles in your thresholded image. OpenCV provides a built-on method to detect circles using Hough transform, more info here. You can take advantage of this function to retain only circles that have a radius in a given range.
Another possibility is to implement connected component labeling (CCL) into your demo program.
I believe that it was removed at some point in verions 2.x of OpenCV, but a basic implementation of the two-pass version is straightforward from the Wikipedia page.
CCL will assign a unique ID for each object after thresholding. You then have to implement matching between the objects at frame (T-1) and objects in frame (T) (for example based on some nearest distance criterion) and possibly trajectory filtering or smoothing, but this would definitely give you some extra-points.
I am trying to implement a grabcut algorithm in OpenCV using C++
I stumble upon this site and found a very simple way how to do it. Unfortunately, it seems like the code is not working for me
#include "opencv2/opencv.hpp"
#include <iostream>
using namespace cv;
using namespace std;
int main( )
{
// Open another image
Mat image;
image= cv::imread("images/mango11a.jpg");
// define bounding rectangle
cv::Rect rectangle(50,70,image.cols-150,image.rows-180);
cv::Mat result; // segmentation result (4 possible values)
cv::Mat bgModel,fgModel; // the models (internally used)
// GrabCut segmentation
cv::grabCut(image, // input image
result, // segmentation result
rectangle,// rectangle containing foreground
bgModel,fgModel, // models
1, // number of iterations
cv::GC_INIT_WITH_RECT); // use rectangle
cout << "oks pa dito" <<endl;
// Get the pixels marked as likely foreground
cv::compare(result,cv::GC_PR_FGD,result,cv::CMP_EQ);
// Generate output image
cv::Mat foreground(image.size(),CV_8UC3,cv::Scalar(255,255,255));
image.copyTo(foreground,result); // bg pixels not copied
// draw rectangle on original image
cv::rectangle(image, rectangle, cv::Scalar(255,255,255),1);
cv::namedWindow("Image");
cv::imshow("Image",image);
// display result
cv::namedWindow("Segmented Image");
cv::imshow("Segmented Image",foreground);
waitKey();
return 0;
}
Can anyone help me with this please? What is supposed to be the problem
PS: NO errors were printed while compiling.
check your settings again. I just executed the same tutorial and it worked fine for me.
I have a code in OpenCV (in C++) which uses "haarcascade_mcs_upperbody.xml" to detect upper body.
It detects single upper body. How can I make it detect multiple upper bodies.
I think CV_HAAR_FIND_BIGGEST_OBJECT is detecting only the biggest object. But I am not knowing how to solve this issue
The code goes like this:
int main(int argc, const char** argv)
{
CascadeClassifier body_cascade;
body_cascade.load("haarcascade_mcs_upperbody.xml");
VideoCapture captureDevice;
captureDevice.open(0);
Mat captureFrame;
Mat grayscaleFrame;
namedWindow("outputCapture", 1);
//create a loop to capture and find faces
while(true)
{
//capture a new image frame
captureDevice>>captureFrame;
//convert captured image to gray scale and equalize
cvtColor(captureFrame, grayscaleFrame, CV_BGR2GRAY);
equalizeHist(grayscaleFrame, grayscaleFrame);
//create a vector array to store the face found
std::vector<Rect> bodies;
//find faces and store them in the vector array
body_cascade.detectMultiScale(grayscaleFrame, faces, 1.1, 3,
CV_HAAR_FIND_BIGGEST_OBJECT|CV_HAAR_SCALE_IMAGE, Size(30,30));
//draw a rectangle for all found faces in the vector array on the original image
for(int i = 0; i < faces.size(); i++)
{
Point pt1(bodies[i].x + bodies[i].width, bodies[i].y + bodies[i].height);
Point pt2(bodies[i].x, bodies[i].y);
rectangle(captureFrame, pt1, pt2, cvScalar(0, 255, 0, 0), 1, 8, 0);
}
//print the output
imshow("outputCapture", captureFrame);
//pause for 33ms
waitKey(33);
}
return 0;
}
It seems there is some inconsistency in your code, since face_cascade is not defined anywhere, but I assume its type is CascadeClassifier.
detectMultiScale stores all detected objects in the faces vector. Are you sure it contains only one object?
Try removing the CV_HAAR_FIND_BIGGEST_OBJECT flag, because you want all objects to be detected, and not only the biggest one.
Also, make sure you set the minSize and maxSize parameters correctly (see documentation), since those parameters determine the minimal and maximal detectable object sizes.
Is there a quick solution to specify the ROI only within the contours of the blob I'm intereseted in?
My ideas so far:
Using the boundingRect, but it contains too much stuff I don't want to analyse.
Applying goodFeaturesToTrack to the whole image and then loop through the output coordinates to eliminate the once outside my blobs contour
Thanks in advance!
EDIT
I found what I need: cv::pointPolygonTest() seems to be the right thing, but I'm not sure how to implement it …
Here's some code:
// ...
IplImage forground_ipl = result;
IplImage *labelImg = cvCreateImage(forground.size(), IPL_DEPTH_LABEL, 1);
CvBlobs blobs;
bool found = cvb::cvLabel(&forground_ipl, labelImg, blobs);
IplImage *imgOut = cvCreateImage(cvGetSize(&forground_ipl), IPL_DEPTH_8U, 3);
if (found) {
vb::CvBlob *greaterBlob = blobs[cvb::cvGreaterBlob(blobs)];
cvb::cvRenderBlob(labelImg, greaterBlob, &forground_ipl, imgOut);
CvContourPolygon *polygon = cvConvertChainCodesToPolygon(&greaterBlob->contour);
}
"polygon" contains the contour I need.
goodFeaturesToTrack is implemented this way:
- (std::vector<cv::Point2f>)pointsFromGoodFeaturesToTrack:(cv::Mat &)_image
{
std::vector<cv::Point2f> corners;
cv::goodFeaturesToTrack(_image,corners, 100, 0.01, 10);
return corners;
}
So next I need to loop through the corners and check each point with cv::pointPolygonTest(), right?
You can create a mask over your interest region:
EDIT
How to make a mask:
Make a mask;
Mat mask(origImg.size(), CV_8UC1);
mask.setTo(Scalar::all(0));
// here I assume your contour is extracted with findContours,
// and is stored in a vector<vector<Point>>
// and that you know which contour is the blob
// if it's not the case, use fillPoly instead of drawContour();
Scalar color(255,255,255); // white. actually, it's monchannel.
drawContours(mask, contours, contourIdx, color );
// fillPoly(Mat& img, const Point** pts, const int* npts,
// int ncontours, const Scalar& color)
And now you're ready to use it. BUT, look carefully at the result - I have heard about some bugs in OpenCV regarding the mask parameter for feature extractors, and I am not sure if it's about this one.
// note the mask parameter:
void goodFeaturesToTrack(InputArray image, OutputArray corners, int maxCorners,
double qualityLevel, double minDistance,
InputArray mask=noArray(), int blockSize=3,
bool useHarrisDetector=false, double k=0.04 )
This will also improve the speed of your aplication - goodFeaturesToTrack eats a hoge amount of time, and if you apply it only on a smaller image, the overall gain is significant.
I am a newbie to openCV. I have installed the opencv library on a ubuntu system, compiled it and trying to look into some image/video processing apps in opencv to understand more.
I am interested to know if OpenCV library has any algorithm/class for removal flicker in captured videos? If yes what document or code should I should look deeper into?
If openCV does not have it, are there any standard implementations in some other Video processing library/SDK/Matlab,.. which provide algorithms for flicker removal from video sequences?
Any pointers would be useful
Thank you.
-AD.
I don't know any standard way to deflicker a video.
But VirtualDub is a Video Processing software which has a Filter for deflickering the video. You can find it's filter source and documents (algorithm description probably) here.
I wrote my own Deflicker C++ function. here it is. You can cut and paste this code as is - no headers needed other than the usual openCV ones.
Mat deflicker(Mat,int);
Mat prevdeflicker;
Mat deflicker(Mat Mat1,int strengthcutoff = 20){ //deflicker - compares each pixel of the frame to a previously stored frame, and throttle small changes in pixels (flicker)
if (prevdeflicker.rows){//check if we stored a previous frame of this name.//if not, theres nothing we can do. clone and exit
int i,j;
uchar* p;
uchar* prevp;
for( i = 0; i < Mat1.rows; ++i)
{
p = Mat1.ptr<uchar>(i);
prevp = prevdeflicker.ptr<uchar>(i);
for ( j = 0; j < Mat1.cols; ++j){
Scalar previntensity = prevp[j];
Scalar intensity = p[j];
int strength = abs(intensity.val[0] - previntensity.val[0]);
if(strength < strengthcutoff){ //the strength of the stimulus must be greater than a certain point, else we do not want to allow the change
//value 25 works good for medium+ light. anything higher creates too much blur around moving objects.
//in low light however this makes it worse, since low light seems to increase contrasts in flicker - some flickers go from 0 to 255 and back. :(
//I need to write a way to track large group movements vs small pixels, and only filter out the small pixel stuff. maybe blur first?
if(intensity.val[0] > previntensity.val[0]){ // use the previous frames value. Change it by +1 - slow enough to not be noticable flicker
p[j] = previntensity.val[0] + 1;
}else{
p[j] = previntensity.val[0] - 1;
}
}
}
}//end for
}
prevdeflicker = Mat1.clone();//clone the current one as the old one.
return Mat1;
}
Call it as: Mat= deflicker(Mat). It needs a loop, and a greyscale image, like so:
for(;;){
cap >> frame; // get a new frame from camera
cvtColor( frame, src_grey, CV_RGB2GRAY ); //convert to greyscale - simplifies everything
src_grey = deflicker(src_grey); // this is the function call
imshow("grey video", src_grey);
if(waitKey(30) >= 0) break;
}