Dashu's profile - activity

I am implementing PCA function, so I can not just call PCA function of OpenCV. I have trouble in calculating eigenvectors using Eigen function, input covariance matrix is 10000x10000 (because image size is 100x100, so 10000 features for one image, training set is only 5 images), eigenvectors returned by Eigen is not usual, every row of eigenvectors has 9999 "0" and only one "1", 00000000.....0010000....00000, I think this vector is normalised already. I try to use low dimension input covariance matrix, eigenvectors is ok. I also try to use Eigen function of Eigen library(https://eigen.tuxfamily.org), but it take a lot of time and I can not wait. Any function from OpenCV I can use? Or I need to implement my own Eigen function to reduce cost?

@StevenPuttemans are there any tutorial for building opencv with qt?

@StevenPuttemans Thanks!

@StevenPuttemans highgui have check-box and button? I can not find

Hi friends, I am writing vision program with OpenCV in Linux, highgui of OpenCV is not suitable for me, so I made a GUI with QT, but QT take too much cpu and memory, I have to write another GUI for vision code, I need your suggestions! The picture show the GUI design, new GUI may not be beacutiful, I just want the basic function. Thanks!

Hi, friends, Happy New Year 2014! I am doing color tracking using OpenCV,I want to rewrite the follwing code, I hope it can be a looping or use function ,so less code. In fact, it's a very straight program. I need your suggestions. Thanks again!

#include <stdio.h>
#include "cv.h"
#include "highgui.h"

int main() {
    /// Variables /////////////////////////////////////////////////////////
    CvMemStorage *storage = cvCreateMemStorage(0); 
    CvSeq *contour_R, *contour_Y, *contmax_R, *contmax_Y;
    IplImage *frame, *imgHSV, *imgThresh,*imgRed, *imgYellow;
    ///////////////////////////////////////////////////////////////////////
    cvNamedWindow("Original", 1);
    cvMoveWindow("Original", 750, 100);
    cvNamedWindow("Red", 1);
    cvMoveWindow("Red", 100, 100);
    cvNamedWindow("Yellow", 1);
    cvMoveWindow("Yellow", 420, 100);
    cvNamedWindow("Result", 1);
    cvMoveWindow("Result", 1080, 100);

    frame = cvLoadImage("color.jpg",1);

    if (frame == NULL) {
        printf("Image Fail\n");
        return -1;
    }

    imgHSV = cvCreateImage(cvGetSize(frame), IPL_DEPTH_8U, 3); 
    cvCvtColor(frame, imgHSV, CV_BGR2HSV);  // convert RGB to HSV

    ///////////////For Red Color////////////////////////////////////////////      
    imgRed=cvCreateImage(cvGetSize(imgHSV),IPL_DEPTH_8U, 1); // create binary image
    cvInRangeS(imgHSV, cvScalar(160,160,60,0), cvScalar(179,255,255,0), imgRed); // scan red color (HSV)
    cvFindContours(imgRed, storage, &contour_R, sizeof(CvContour), CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE,cvPoint(0,0)); 
    cvZero(imgRed);

    int area,maxArea = 0;

    for(;contour_R != 0;contour_R = contour_R->h_next)    // find the largest red area
    { 
         area = fabs(cvContourArea(contour_R, CV_WHOLE_SEQ,1 ));
         if(area > maxArea){ 
                contmax_R = contour_R;
                maxArea = area;
               }    
    }

    cvDrawContours(imgRed, contmax_R, CV_RGB(255,255,255), CV_RGB(255,255,255), 0, CV_FILLED, 8, cvPoint(0, 0));// draw largest red contour 
    CvRect rect_R = cvBoundingRect(contmax_R,0); 
    cvRectangle(frame, cvPoint(rect_R.x, rect_R.y), cvPoint(rect_R.x + rect_R.width, rect_R.y + rect_R.height),CV_RGB(0, 255, 0), 1, 8, 0); 
    printf("Red 1 (%d, %d)-(%d, %d)\n",rect_R.x, rect_R.y,rect_R.x + rect_R.width, rect_R.y + rect_R.height);
    /////////For Yellow Color//////////////////////////////////////////////////////////////////////////////
    imgYellow=cvCreateImage(cvGetSize(imgHSV),IPL_DEPTH_8U, 1); 
    cvInRangeS(imgHSV, cvScalar(22,160,60,0), cvScalar(38,255,255,0), imgYellow);
    cvFindContours(imgYellow, storage, &contour_Y, sizeof(CvContour), CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE,cvPoint(0,0)); 
    cvZero(imgYellow);

    maxArea = 0;

    for(;contour_Y != 0;contour_Y = contour_Y->h_next)  
    { 
        area = fabs(cvContourArea(contour_Y, CV_WHOLE_SEQ,1 ));
         if(area > maxArea){ 
                contmax_Y = contour_Y;
                maxArea = area;
               }            

    }

    cvDrawContours(imgYellow, contmax_Y, CV_RGB(255,255,255), CV_RGB(255,255,255), 0, CV_FILLED, 8, cvPoint(0, 0)); 
    CvRect rect_Y = cvBoundingRect(contmax_Y,0);
    cvRectangle(frame, cvPoint(rect_Y.x, rect_Y.y), cvPoint(rect_Y.x + rect_Y.width, rect_Y.y + rect_Y.height),CV_RGB(0, 0, 255), 1, 8, 0); 
    printf("Yellow 1 (%d, %d)-(%d, %d)\n",rect_Y.x, rect_Y.y,rect_Y.x + rect_Y.width, rect_Y.y + rect_Y.height);
    //////////////////////////////////////////////////////////////////    
    imgThresh=cvCreateImage(cvGetSize(imgHSV),IPL_DEPTH_8U, 1);
    cvAdd(imgRed,imgYellow,imgThresh,0); // 

    cvShowImage("Original", frame);
    cvShowImage("Red", imgRed);
    cvShowImage("Yellow", imgYellow);
    cvShowImage("Result", imgThresh);

    while (1) {
       int c = cvWaitKey(10);
       if((char)c==27 ) break;  
    }

    cvReleaseMemStorage(&storage);  
    cvReleaseImage(&imgThresh);
    cvReleaseImage(&imgRed);
    cvReleaseImage(&imgYellow);
    cvReleaseImage(&frame);
    cvReleaseImage(&imgHSV);

    cvDestroyAllWindows();

    return 0;
}

Hi, friends, I am writing vision code(C or C++) with OpenCV and cvBlob, can track N(1-5) different color at the same time. For example, the attached picture include 7 or 8 color, I want to detect 5 color (black,red,blue,green,yellow) at same time time and find the largest area of each color, track the five color area and report their position. How should I do? I need your suggestions!

Hi, friends, I am coding using opencv. I want to find three largest contour in picture/video, I have write code that can find two largest contour, I have difficulty in finding third largest, so I need your suggestions,Merry Christmas! Here is my core code, how to change.

CvSeq *cont = 0
cvFindContours( tempImg, storage, &cont, sizeof(CvContour), 
CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE, cvPoint(0,0) ); 

CvSeq *contmax = 0;
CvSeq *contmax2 = contmax;

for(;cont;cont = cont->h_next) //get the two max area, and mark
{
    area = fabs(cvContourArea( cont, CV_WHOLE_SEQ )); 
    printf("area == %lf\n", area);
    if(area > maxArea)
    {
        contmax2 = contmax;
        max2Area = maxArea;
        contmax = cont;
        maxArea = area;
    }
    else if(area > max2Area && area < maxArea)
    {
        contmax2 = cont;
        max2Area = area;
    }

}
CvRect aRect = cvBoundingRect( contmax, 0 );
CvRect bRect = cvBoundingRect( contmax2, 0 );

Thanks, Haris!

Hi, Haris, how should I get (x,y) of top left corner of rectangular. Thanks

Hi friends, I am writing colortracking code using C with OpenCV. I want to detect red color area and remove other small red area or noise, mark max red area with drawing rectangular box and printf the coordinate of the top left corner of box. This is requirement. Now I can detect red color ,but can not draw rectangular box and get the (x,y), What should I do now? Thx!

#include <stdio.h>
#include "cv.h"
#include "highgui.h"

IplImage* GetThresholdedImage(IplImage* imgHSV){        
       IplImage* imgThresh=cvCreateImage(cvGetSize(imgHSV),IPL_DEPTH_8U, 1); //Create binary image(1 channel)
       cvInRangeS(imgHSV, cvScalar(170,160,60,0), cvScalar(180,255,255,0), imgThresh); //check if array elements lie between lower and upper
       return imgThresh;
} 

int main(){
      CvCapture* capture ;       
      capture = cvCaptureFromCAM(-1); //'-1' means default camera

      cvSetCaptureProperty(capture,CV_CAP_PROP_FRAME_WIDTH,320);
      cvSetCaptureProperty(capture,CV_CAP_PROP_FRAME_HEIGHT,240);

      if(!capture){
            printf("Capture failure\n");
            return -1;
      }

      IplImage* frame;
      cvNamedWindow("Original",1);      
      cvNamedWindow("Result",1);

      while(1){

            frame = cvQueryFrame(capture);            
            if(!frame) break;

            frame=cvCloneImage(frame); // why clone? because the returned image shouldn't be released or modified
            //cvSmooth(frame, frame, CV_GAUSSIAN,3,3,0,0); //Smooth the original image using Gaussian kernel 
            cvDilate(frame,frame,NULL,1);
            cvErode(frame,frame,NULL,1);  // suture breaks,smooth image          

            IplImage* imgHSV = cvCreateImage(cvGetSize(frame), IPL_DEPTH_8U, 3); 
            cvCvtColor(frame, imgHSV, CV_BGR2HSV); //Change the color format from BGR to HSV
            IplImage* imgThresh = GetThresholdedImage(imgHSV);

            cvShowImage("Result", imgThresh);            
            cvShowImage("Original", frame);

            //Clean up used images          
            cvReleaseImage(&imgHSV);
            cvReleaseImage(&imgThresh);            
            cvReleaseImage(&frame);

            //Wait 10ms
            int c = cvWaitKey(10);
            //If 'ESC' is pressed, break the loop
            if((char)c==27 ) break;      
      }

      cvDestroyAllWindows() ;
      cvReleaseCapture(&capture);     

      return 0;
}

I am writing C code (not C++) with OpenCV and cvBlob. For cvblob, always has error " /usr/local/include/cvblob.h:33:20: fatal error: iostream: No such file or directory " In my code, header has cvblob.h. here is cvblob.hlink text For OpenCV, everything is ok. so for C, how to use cvBlob?