Adjust code to detect multiple circles instead of just 1 in OPENCV - opencv

I have got this circle detection working but only detects 1 circle. How would I adjust code to detect multiple circles(max circles that will be detected is 22 as using it for snooker). I presume i would be editing the circle detectoin method but i am stuck:(
#include <stdio.h>
#include "cv.h"
#include "highgui.h"
#include <iostream>
#include <math.h>
#include <string.h>
#include <conio.h>
using namespace std;
IplImage* img = 0;
CvMemStorage * cstorage;
CvMemStorage * hstorage;
void detectCircle( IplImage *frame );
int main( int argc, char **argv )
{
CvCapture *capture = 0;
IplImage *frame = 0;
int key = 0;
hstorage = cvCreateMemStorage( 0 );
cstorage = cvCreateMemStorage( 0 );
//CvVideoWriter *writer = 0;
//int colour = 1;
//int fps = 25;
//int frameW = 640;
//int frameH = 480;
//writer = cvCreateVideoWriter("test.avi",CV_FOURCC('P', 'I', 'M', '1'),fps,cvSize(frameW,frameH),colour);
//initialise camera
capture = cvCaptureFromCAM( 0 );
//check if camera present
if ( !capture )
{
fprintf( stderr, "cannot open webcam\n");
return 1;
}
//create a window
cvNamedWindow( "Snooker", CV_WINDOW_AUTOSIZE );
while(key !='q')
{
//get frame
frame = cvQueryFrame(capture);
//int nFrames = 50;
//for (int i=0; i<nFrames;i++){
//cvGrabFrame(capture);
//frame = cvRetrieveFrame(capture);
//cvWriteFrame(writer, frame);
//}
//check for frame
if( !frame ) break;
detectCircle(frame);
//display current frame
//cvShowImage ("Snooker", frame );
//exit if Q pressed
key = cvWaitKey( 20 );
}
// free memory
cvDestroyWindow( "Snooker" );
cvReleaseCapture( &capture );
cvReleaseMemStorage( &cstorage);
cvReleaseMemStorage( &hstorage);
//cvReleaseVideoWriter(&writer);
return 0;
}
**void detectCircle( IplImage * img )
{
int px;
int py;
int edge_thresh = 1;
IplImage *gray = cvCreateImage( cvSize(img->width,img->height), 8, 1);
IplImage *edge = cvCreateImage( cvSize(img->width,img->height), 8, 1);
cvCvtColor(img, gray, CV_BGR2GRAY);
gray->origin = 1;
// color threshold
cvThreshold(gray,gray,100,255,CV_THRESH_BINARY);
// smooths out image
cvSmooth(gray, gray, CV_GAUSSIAN, 11, 11);
// get edges
cvCanny(gray, edge, (float)edge_thresh, (float)edge_thresh*3, 5);
// detects circle
CvSeq* circle = cvHoughCircles(gray, cstorage, CV_HOUGH_GRADIENT, 1, gray->height/50, 5, 35);
// draws circle and its centerpoint
float* p = (float*)cvGetSeqElem( circle, 0 );
if( p==null ){ return;}
cvCircle( img, cvPoint(cvRound(p[0]),cvRound(p[1])), 3, CV_RGB(255,0,0), -1, 8, 0 );
cvCircle( img, cvPoint(cvRound(p[0]),cvRound(p[1])), cvRound(p[2]), CV_RGB(200,0,0), 1, 8, 0 );
px=cvRound(p[0]);
py=cvRound(p[1]);**
cvShowImage ("Snooker", img );
}

Your code finds all circles - you just draw one:
// draws circle and its centerpoint
float* p = (float*)cvGetSeqElem( circle, 0 );
if( p==null ){ return;}
cvCircle( img, cvPoint(cvRound(p[0]),cvRound(p[1])), 3, CV_RGB(255,0,0), -1, 8, 0 );
cvCircle( img, cvPoint(cvRound(p[0]),cvRound(p[1])), cvRound(p[2]), CV_RGB(200,0,0), 1, 8, 0);
px=cvRound(p[0]);
py=cvRound(p[1]);
You should do it in cycle, something like:
for( int i=0; i < circles->total; i++ )
{
float* p = (float*) cvGetSeqElem( circles, i );
// ... d draw staff
}

Related

Accurate subpixel edge location in C (OPENCV)

I want to find subpixel and I resarched this topic However I think that subpixels must be such as 152.6 , 49.3 ...
I find this document in opencv http://docs.opencv.org/2.4/modules/imgproc/doc/feature_detection.html?highlight=cornersubpix#cornersubpix
And I try this code
#include <iostream>
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
using namespace cv;
using namespace std;
Mat src, src_gray;
int maxCorners = 10;
int maxTrackbar = 50;
RNG rng(11111);
char* source_window = "Image";
void goodFeaturesToTrack_Demo( int, void* );
int main( int argc, char** argv )
{
src = imread( "a.png", 1 );
cvtColor( src, src_gray, CV_BGR2GRAY );
namedWindow( source_window, CV_WINDOW_AUTOSIZE );
createTrackbar( "Max corners:", source_window, &maxCorners, maxTrackbar, goodFeaturesToTrack_Demo);
imshow( source_window, src );
goodFeaturesToTrack_Demo( 0, 0 );
waitKey(0);
return(0);
}
void goodFeaturesToTrack_Demo( int, void* )
{
if( maxCorners < 1 )
{ maxCorners = 1; }
vector<Point2f> corners;
double qualityLevel = 0.01;
double minDistance = 10;
int blockSize = 3;
bool useHarrisDetector = false;
double k = 0.04;
Mat copy;
copy = src.clone();
goodFeaturesToTrack( src_gray,corners,maxCorners,qualityLevel,minDistance,Mat(),blockSize,useHarrisDetector,k );
cout<<"** Number of corners detected: "<<corners.size()<<endl;
int r = 4;
for( int i = 0; i < corners.size(); i++ )
{ circle( copy, corners[i], r, Scalar(rng.uniform(0,255), rng.uniform(0,255),rng.uniform(0,255)), -1, 8, 0 ); }
namedWindow( source_window, CV_WINDOW_AUTOSIZE );
imshow( source_window, copy );
Size winSize = Size( 10, 10 );
Size zeroZone = Size( -1, -1 );
TermCriteria criteria = TermCriteria( CV_TERMCRIT_EPS + CV_TERMCRIT_ITER, 40, 0.001 );
cornerSubPix( src_gray, corners, winSize, zeroZone, criteria );
for( int i = 0; i < corners.size(); i++ )
{ cout<<" -- Refined Corner ["<<i<<"] ("<<corners[i].x<<","<<corners[i].y<<")"<<endl; }
}
But I have this result:
this code ofind only corner's subpixel I want to find edge's subpixel

Why is the lines of optical flow are not drawn in my code

I'm trying to use the optical flow, but optical flow lines are not drawn and instead only points, what's the problem ?
Here is the source code of the project. Looked through the debugger. GDB shows that always p0.x = p1.x and p0.y = p1.y. but why ? Sorry for my bad English.
#include "opencv/cv.h"
#include "opencv2/core/core.hpp"
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/objdetect/objdetect.hpp>
#include <opencv2/opencv.hpp>
#include <iostream>
#include <stdio.h>
std::vector<cv::Point2f> corners;
std::vector<cv::Point2f> corners_b;
double qualityLevel = 0.01;
double minDistance = 10;
int blockSize = 3;
bool useHarrisDetector = false;
double k = 0.04;
int maxCorners = 200;
int maxTrackbar = 100;
void MotionDetection(cv::Mat frame1, cv::Mat frame2)
{
cv::Mat prev, next;
cvtColor(frame1, prev, CV_BGR2GRAY);
cvtColor(frame2, next, CV_BGR2GRAY);
goodFeaturesToTrack( prev,
corners,
maxCorners,
qualityLevel,
minDistance,
cv::Mat(),
blockSize,
useHarrisDetector,
k );
cornerSubPix(prev,
corners,
cvSize( 10, 10 ) ,
cvSize( -1, -1 ),
cvTermCriteria( CV_TERMCRIT_ITER | CV_TERMCRIT_EPS, 20, 0.03 ) );
std::vector<uchar> features_found;
features_found.reserve(maxCorners);
std::vector<float> feature_errors;
feature_errors.reserve(maxCorners);
calcOpticalFlowPyrLK(prev, next, corners, corners_b, features_found,
feature_errors, cvSize( 10, 10 ), 5, cvTermCriteria( CV_TERMCRIT_ITER | CV_TERMCRIT_EPS, 20, 0.3 ), 0);
IplImage g = next;
for( int i = 0; i < maxCorners; ++i )
{
CvPoint p0 = cvPoint( cvRound( corners[i].x ), cvRound( corners[i].y ) );
CvPoint p1 = cvPoint( cvRound( corners_b[i].x ), cvRound( corners_b[i].y ) );
cvLine( &g, p0, p1, CV_RGB(255,0,0), 3, CV_AA );
}
cv::Mat rs(&g);
imshow( "result window", rs );
int key = cv::waitKey(5);
}
int main(int argc, char* argv[])
{
cv::VideoCapture cap(0);
if(!cap.isOpened())
{
std::cout<<"[!] Error: cant open camera!"<<std::endl;
return -1;
}
cv::Mat edges;
cv::namedWindow("result window", 1);
cv::Mat frame, frame2;
cap >> frame;
while(1)
{
cap >> frame2;
MotionDetection(frame, frame2);
}
return 0;
}
in you Main function frame is clone frame2.
I think, that
cap >> frame2;
frame2.copyTo( frame );
instead of
cap >> frame;
thats all

histogram on opencv

hey i tried to made a histogram that shows frames substraction, the code is running but i got gray window without result.
the message on the command window is:
Compiler did not align stack variables. Libavcodec has been miscompiled
and may be very slow or crash. This is not a bug in libavcodec,
but in the compiler. You may try recompiling using gcc >= 4.2.
Do not report crashes to FFmpeg developers.
OpenCV Error: Assertion failed (images[j].channels() == 1) in unknown function,
file ........\ocv\opencv\src\cv\cvhistogram.cpp, line 137
here is the code someone have an idea?thanks for help.....
int main()
{
int key = 0;
CvCapture* capture = cvCaptureFromAVI( "macroblock.mpg" );
IplImage* frame = cvQueryFrame( capture );
IplImage* currframe = cvCreateImage(cvGetSize(frame),IPL_DEPTH_8U,3);
IplImage* destframe = cvCreateImage(cvGetSize(frame),IPL_DEPTH_8U,3);
IplImage* imgHistogram = 0;
CvHistogram* hist;
if ( !capture )
{
fprintf( stderr, "Cannot open AVI!\n" );
return 1;
}
int fps = ( int )cvGetCaptureProperty( capture, CV_CAP_PROP_FPS );
cvNamedWindow( "dest", CV_WINDOW_AUTOSIZE );
cvNamedWindow( "imgHistogram", CV_WINDOW_AUTOSIZE );
while( key != 'x' )
{
frame = cvQueryFrame( capture );
currframe = cvCloneImage( frame );
frame = cvQueryFrame( capture );
cvSub(frame,currframe,destframe);
int bins = 256;
int hsize[] = {bins};
float max_value = 0, min_value = 0;
float value;
int normalized;
float xranges[] = {0, 256};
float* ranges[] = {xranges};
IplImage* planes[] = {destframe};
hist = cvCreateHist(1, hsize, CV_HIST_ARRAY, ranges,1);
cvCalcHist(planes, hist, 0, NULL);
cvGetMinMaxHistValue(hist, &min_value, &max_value);
// printf("Minimum Histogram Value: %f, Maximum Histogram Value: %f\n", min_value, max_value);
imgHistogram = cvCreateImage(cvSize(bins, 50),IPL_DEPTH_8U,3);
cvRectangle(imgHistogram, cvPoint(0,0), cvPoint(256,50), CV_RGB(255,255,255),-1);
for(int i=0; i < bins; i++){
value = cvQueryHistValue_1D(hist, i);
normalized = cvRound(value*50/max_value);
cvLine(imgHistogram,cvPoint(i,50), cvPoint(i,50-normalized), CV_RGB(0,0,0));
}
if(key==27 )break;
cvShowImage( "dest",destframe);
cvShowImage( "imgHistogram",imgHistogram);
key = cvWaitKey( 1000 / 10 );
}
cvDestroyWindow( "dest" );
cvReleaseCapture( &capture );
return 0;
}
Since you are trying to show a 1D histogram, the histogram plane needs to be in grayscale. So, you need to convert the resulting image from cvSub() to grayscale first. Try
IplImage *gray = NULL;
gray = cvCreateImage(cvGetSize(frame), IPL_DEPTH_8U, 1);
while(key != 'x') {
...
cvSub(frame, currframe, destframe);
cvCvtColor(destframe, gray, CV_BGR2GRAY);
...
IplImage* planes[] = {gray};
..
}
Let me know if it works for you.

How to increase haar detector's window size in OpenCV

I am using the code available in this website: http://nashruddin.com/OpenCV_Face_Detection to do face detection.
I would like to increase the size of the detected face region. I am not sure how to do it. Need some help on it..
The code i am using is this:
//
#include "stdafx.h"
#include <stdio.h>
#include <cv.h>
#include <highgui.h>
CvHaarClassifierCascade *cascade;
CvMemStorage *storage;
void detectFaces( IplImage *img );
int main( int argc, char** argv )
{
CvCapture *capture;
IplImage *frame;
int key;
char *filename = "C:/OpenCV2.1/data/haarcascades/haarcascade_frontalface_alt.xml";
cascade = ( CvHaarClassifierCascade* )cvLoad( filename, 0, 0, 0 );
storage = cvCreateMemStorage( 0 );
capture = cvCaptureFromCAM( 0 );
assert( cascade && storage && capture );
cvNamedWindow( "video", 1 );
while( key != 'q' ) {
frame = cvQueryFrame( capture );
if( !frame ) {
fprintf( stderr, "Cannot query frame!\n" );
break;
}
cvFlip( frame, frame, -1 );
frame->origin = 0;
detectFaces( frame );
key = cvWaitKey( 10 );
}
cvReleaseCapture( &capture );
cvDestroyWindow( "video" );
cvReleaseHaarClassifierCascade( &cascade );
cvReleaseMemStorage( &storage );
return 0;
}
void detectFaces( IplImage *img )
{
int i;
CvSeq *faces = cvHaarDetectObjects(
img,
cascade,
storage,
1.1,
3,
0 /*CV_HAAR_DO_CANNY_PRUNNING*/,
cvSize( 40, 40 ) );
for( i = 0 ; i < ( faces ? faces->total : 0 ) ; i++ ) {
CvRect *r = ( CvRect* )cvGetSeqElem( faces, i );
cvRectangle( img,
cvPoint( r->x, r->y ),
cvPoint( r->x + r->width, r->y + r->height ),
CV_RGB( 255, 0, 0 ), 1, 8, 0 );
}
cvShowImage( "video", img );
}
This increases the size of the rectangle around the face. If you meant increasing the haar detector's window size, please update your question.
int padding_width = 30; // pixels
int padding_height = 30; // pixels
for( i = 0 ; i < ( faces ? faces->total : 0 ) ; i++ ) {
CvRect *r = ( CvRect* )cvGetSeqElem( faces, i );
// Yes yes, all of this could be written much more compactly.
// It was written like this for clarity.
int topleft_x = r->x - (padding_width / 2);
int topleft_y = r->y - (padding_height / 2);
if (topleft_x < 0)
topleft_x = 0;
if (topleft_y < 0)
topleft_y = 0;
int bottomright_x = r->x + r->width + (padding_width / 2);
int bottomright_y = r->y + r->height + (padding_height / 2);
if (bottomright_x >= img->width)
bottomright_x = img->width - 1;
if (bottomright_y >= img->height)
bottomright_y = img->height - 1;
cvRectangle( img,
cvPoint(topleft_x, topleft_y),
cvPoint(bottomright_x, bottomright_y),
CV_RGB( 255, 0, 0 ), 1, 8, 0 );
}

display a video from my webcam trying to implement circle detection

I'm trying to display a video from my webcam (which was working grand) and now I'm trying to implement circle detection into this video stream.
Unhandled exception at 0x001a1a4d in test.exe: 0xC0000005: Access violation reading location 0x00000004.)
The error is linked to the line of code:
cvCircle( img, cvPoint(cvRound(p[0]),cvRound(p[1])), 3, CV_RGB(255,0,0), -1, 8, 0 );.
Can anyone help please?
#include <stdio.h>
#include "cv.h"
#include "highgui.h"
#include <iostream>
#include <math.h>
#include <string.h>
#include <conio.h>
using namespace std;
IplImage* img = 0;
CvMemStorage * cstorage;
CvMemStorage * hstorage;
void detectCircle( IplImage *frame );
int main( int argc, char **argv )
{
CvCapture *capture = 0;
IplImage *frame = 0;
int key = 0;
hstorage = cvCreateMemStorage( 0 );
cstorage = cvCreateMemStorage( 0 );
//CvVideoWriter *writer = 0;
//int colour = 1;
//int fps = 25;
//int frameW = 640;
//int frameH = 480;
//writer = cvCreateVideoWriter("test.avi",CV_FOURCC('P', 'I', 'M', '1'),fps,cvSize(frameW,frameH),colour);
//initialise camera
capture = cvCaptureFromCAM( 0 );
//check if camera present
if ( !capture )
{
fprintf( stderr, "cannot open webcam\n");
return 1;
}
//create a window
cvNamedWindow( "Snooker", CV_WINDOW_AUTOSIZE );
while(key !='q')
{
//get frame
frame = cvQueryFrame(capture);
//int nFrames = 50;
//for (int i=0; i<nFrames;i++){
//cvGrabFrame(capture);
//frame = cvRetrieveFrame(capture);
//cvWriteFrame(writer, frame);
//}
//check for frame
if( !frame ) break;
detectCircle(frame);
//display current frame
//cvShowImage ("Snooker", frame );
//exit if Q pressed
key = cvWaitKey( 20 );
}
// free memory
cvDestroyWindow( "Snooker" );
cvReleaseCapture( &capture );
cvReleaseMemStorage( &cstorage);
cvReleaseMemStorage( &hstorage);
//cvReleaseVideoWriter(&writer);
return 0;
}
void detectCircle( IplImage * img )
{
int px;
int py;
int edge_thresh = 1;
IplImage *gray = cvCreateImage( cvSize(img->width,img->height), 8, 1);
IplImage *edge = cvCreateImage( cvSize(img->width,img->height), 8, 1);
cvCvtColor(img, gray, CV_BGR2GRAY);
gray->origin = 1;
// color threshold
cvThreshold(gray,gray,100,255,CV_THRESH_BINARY);
// smooths out image
cvSmooth(gray, gray, CV_GAUSSIAN, 11, 11);
// get edges
cvCanny(gray, edge, (float)edge_thresh, (float)edge_thresh*3, 5);
// detects circle
CvSeq* circle = cvHoughCircles(gray, cstorage, CV_HOUGH_GRADIENT, 1, gray->height/50, 5, 35);
// draws circle and its centerpoint
float* p = (float*)cvGetSeqElem( circle, 0 );
cvCircle( img, cvPoint(cvRound(p[0]),cvRound(p[1])), 3, CV_RGB(255,0,0), -1, 8, 0 );
cvCircle( img, cvPoint(cvRound(p[0]),cvRound(p[1])), cvRound(p[2]), CV_RGB(200,0,0), 1, 8, 0 );
px=cvRound(p[0]);
py=cvRound(p[1]);
cvShowImage ("Snooker", img );
}

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