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POOpenCV CvConvexityDefects can't work and can't detect fingers！
 

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  1. POOpenCV CvConvexityDefects can't work and can't detect fingers！
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    <p>I'm using OpenCv to detect fingertips, but now I meet with some obstacles! The findContours &amp; convexHull &amp; convexityDefects method doesn't work with my project. It's my first time to ask a question. Thanks everybody!</p> <p>My code is below:</p> <pre><code>int main() { CvScalar white = cvRealScalar(255); CvScalar black = cvRealScalar(0); CvSeq* contours = 0; CvMemStorage* storage = cvCreateMemStorage(0); IplImage* img = cvLoadImage("h.jpg"); IplImage* imgGray = cvCreateImage(cvGetSize(img), img-&gt;depth, 1); IplImage* contoursImg = cvCreateImage(cvGetSize(img), img-&gt;depth, 1); cvZero(contoursImg); int nWidth = contoursImg-&gt;width; int nHeight = contoursImg-&gt;height; int nChannels = contoursImg-&gt;nChannels; int nStep = contoursImg-&gt;widthStep; for (int i=0; i&lt;nHeight; i++) for(int j=0; j&lt;nWidth; j++) contoursImg-&gt;imageData[i*nStep + j*nChannels] = 255 - contoursImg-&gt;imageData[i*nStep + j*nChannels]; cvCvtColor(img, imgGray, CV_BGR2GRAY); cvThreshold(imgGray, imgGray, 230, 255, CV_THRESH_BINARY); cvSmooth(imgGray, imgGray); cvFindContours(imgGray, storage, &amp;contours, sizeof(CvContour), CV_RETR_LIST, CV_CHAIN_APPROX_SIMPLE, cvPoint(0,0)); contours = cvApproxPoly(contours, sizeof(CvContour), storage, CV_POLY_APPROX_DP, 35, 1); cvDrawContours(contoursImg, contours, CV_RGB(0, 0, 0), CV_RGB(0, 0, 0), 1, 1, 8, cvPoint(0, 0)); CvSeq* hull = cvConvexHull2(contours, 0, CV_CLOCKWISE, 0); CvSeq* defect = cvConvexityDefects(contours, hull, NULL); for(; defect; defect = defect-&gt;h_next) { int nomdef = defect-&gt;total; if(!nomdef) continue; CvConvexityDefect* defectArray = (CvConvexityDefect*)malloc(sizeof(CvConvexityDefect)*nomdef); cvCvtSeqToArray(defect, defectArray, CV_WHOLE_SEQ); for(int i = 0; i &lt; nomdef; i++) { cvCircle(contoursImg, *(defectArray[i].end), 5, CV_RGB(255, 0, 0), -1, 8, 0); cvCircle(contoursImg, *(defectArray[i].start), 5, CV_RGB(0, 255, 0), -1, 8, 0); cvCircle(contoursImg, *(defectArray[i].depth_point), 5, CV_RGB(0, 0, 255), -1, 8, 0); } free(defectArray); } cvNamedWindow("image", 1); cvShowImage("image", contoursImg); cvWaitKey(0); cvReleaseMemStorage(&amp;storage); cvReleaseImage(&amp;img); cvReleaseImage(&amp;imgGray); cvReleaseImage(&amp;contoursImg); cvDestroyWindow("image"); return 0; } </code></pre> <p>This is my hand picture:</p> <p><a href="http://www.billwang.net/bbs/oldattach/2006/12/29/billwang_5315954-038-embed.jpg" rel="nofollow">http://www.billwang.net/bbs/oldattach/2006/12/29/billwang_5315954-038-embed.jpg</a></p>
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    1. COThank you for editing my post~ vasile
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    2. COYour code works like a charm for your image. I am able to generate the contour image. What error are you getting?
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    3. COThank you, go4sri. The code can generate the contour image. But it should also generate small black circles on the fingertips; unfortnately, the result isn't what I want.
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