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POHow to extract width and height of contour in javacv?
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copied!<p>I am developing project on component identification using javacv package (Opencv ). I used a method to return set of rectangles on the image as "CvSeq" What I need to know is how to do following things</p> <ul> <li>How can I get each rectangle from methods output (from CvSeq)?</li> <li>How to access the lengths and width of the rectangle ? </li> </ul> <p>This is the method that returns the rectangles </p> <pre><code>public static CvSeq findSquares( final IplImage src, CvMemStorage storage) { CvSeq squares = new CvContour(); squares = cvCreateSeq(0, sizeof(CvContour.class), sizeof(CvSeq.class), storage); IplImage pyr = null, timg = null, gray = null, tgray; timg = cvCloneImage(src); CvSize sz = cvSize(src.width() & -2, src.height() & -2); tgray = cvCreateImage(sz, src.depth(), 1); gray = cvCreateImage(sz, src.depth(), 1); pyr = cvCreateImage(cvSize(sz.width()/2, sz.height()/2), src.depth(), src.nChannels()); // down-scale and upscale the image to filter out the noise cvPyrDown(timg, pyr, CV_GAUSSIAN_5x5); cvPyrUp(pyr, timg, CV_GAUSSIAN_5x5); cvSaveImage("ha.jpg", timg); CvSeq contours = new CvContour(); // request closing of the application when the image window is closed // show image on window // find squares in every color plane of the image for( int c = 0; c < 3; c++ ) { IplImage channels[] = {cvCreateImage(sz, 8, 1), cvCreateImage(sz, 8, 1), cvCreateImage(sz, 8, 1)}; channels[c] = cvCreateImage(sz, 8, 1); if(src.nChannels() > 1){ cvSplit(timg, channels[0], channels[1], channels[2], null); }else{ tgray = cvCloneImage(timg); } tgray = channels[c]; // try several threshold levels for( int l = 0; l < N; l++ ) { // hack: use Canny instead of zero threshold level. // Canny helps to catch squares with gradient shading if( l == 0 ) { // apply Canny. Take the upper threshold from slider // and set the lower to 0 (which forces edges merging) cvCanny(tgray, gray, 0, thresh, 5); // dilate canny output to remove potential // // holes between edge segments cvDilate(gray, gray, null, 1); } else { // apply threshold if l!=0: cvThreshold(tgray, gray, (l+1)*255/N, 255, CV_THRESH_BINARY); } // find contours and store them all as a list cvFindContours(gray, storage, contours, sizeof(CvContour.class), CV_RETR_LIST, CV_CHAIN_APPROX_SIMPLE); CvSeq approx; // test each contour while (contours != null && !contours.isNull()) { if (contours.elem_size() > 0) { approx = cvApproxPoly(contours, Loader.sizeof(CvContour.class),storage, CV_POLY_APPROX_DP, cvContourPerimeter(contours)*0.02, 0); if( approx.total() == 4 && Math.abs(cvContourArea(approx, CV_WHOLE_SEQ, 0)) > 1000 && cvCheckContourConvexity(approx) != 0 ){ double maxCosine = 0; // for( int j = 2; j < 5; j++ ) { // find the maximum cosine of the angle between joint edges double cosine = Math.abs(angle(new CvPoint(cvGetSeqElem(approx, j%4)), new CvPoint(cvGetSeqElem(approx, j-2)), new CvPoint(cvGetSeqElem(approx, j-1)))); maxCosine = Math.max(maxCosine, cosine); } if( maxCosine < 0.2 ){ cvSeqPush(squares, approx); } } } contours = contours.h_next(); } contours = new CvContour(); } } return squares; } </code></pre> <p>This is the sample original image that I used</p> <p><img src="https://i.stack.imgur.com/pqn2r.png" alt="enter image description here"></p> <p>And this is the image that I got after drawing lines around the matching rectangles </p> <p><img src="https://i.stack.imgur.com/OFOe1.jpg" alt="enter image description here"></p> <p>Actually in above images I'm tying to remove those large rectangles and just need to identify other rectangles so I need some code example to understand how to archive above goals. Please be kind enough to share your experience with me. Thanks ! </p>

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