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copied!<p>I am just in this moment working on the same problem and have a first solution. There's a lot of approaches out there but unfortunately most of them are ugly and slow. My main goal to this point was to stay in the JavaCV/OpenCV-World.</p> <p>These Links pushed me in the right direction:</p> <ol> <li><a href="https://stackoverflow.com/questions/4641817/blob-extraction-in-opencv">Blob extraction in OpenCV</a></li> <li><a href="http://voices.yahoo.com/connected-components-using-opencv-5462975.html?cat=15" rel="nofollow noreferrer">http://voices.yahoo.com/connected-components-using-opencv-5462975.html?cat=15</a></li> <li><a href="http://opencv.willowgarage.com/documentation/cpp/structural_analysis_and_shape_descriptors.html#cv-findcontours" rel="nofollow noreferrer">http://opencv.willowgarage.com/documentation/cpp/structural_analysis_and_shape_descriptors.html#cv-findcontours</a></li> </ol> <p>Here's a complete Demo class that should show you how it's done. Try it with a black background image with simple objects and sharp corners for best results. Make sure to check the second link above to get informed about what's happening in the code. </p> <pre><code>import static com.googlecode.javacpp.Loader.sizeof; import static com.googlecode.javacv.cpp.opencv_core.CV_FILLED; import static com.googlecode.javacv.cpp.opencv_core.CV_RGB; import static com.googlecode.javacv.cpp.opencv_core.IPL_DEPTH_8U; import static com.googlecode.javacv.cpp.opencv_core.cvCreateImage; import static com.googlecode.javacv.cpp.opencv_core.cvCreateMemStorage; import static com.googlecode.javacv.cpp.opencv_core.cvDrawContours; import static com.googlecode.javacv.cpp.opencv_core.cvGetSize; import static com.googlecode.javacv.cpp.opencv_core.cvPoint; import static com.googlecode.javacv.cpp.opencv_highgui.cvLoadImage; import static com.googlecode.javacv.cpp.opencv_highgui.cvSaveImage; import static com.googlecode.javacv.cpp.opencv_imgproc.CV_BGR2GRAY; import static com.googlecode.javacv.cpp.opencv_imgproc.CV_CHAIN_APPROX_SIMPLE; import static com.googlecode.javacv.cpp.opencv_imgproc.CV_RETR_CCOMP; import static com.googlecode.javacv.cpp.opencv_imgproc.CV_THRESH_BINARY; import static com.googlecode.javacv.cpp.opencv_imgproc.cvCvtColor; import static com.googlecode.javacv.cpp.opencv_imgproc.cvFindContours; import static com.googlecode.javacv.cpp.opencv_imgproc.cvThreshold; import java.awt.Color; import java.util.Random; import com.googlecode.javacv.cpp.opencv_core.CvContour; import com.googlecode.javacv.cpp.opencv_core.CvMemStorage; import com.googlecode.javacv.cpp.opencv_core.CvScalar; import com.googlecode.javacv.cpp.opencv_core.CvSeq; import com.googlecode.javacv.cpp.opencv_core.IplImage; /** * A demo for blob extraction using only JavaCV / OpenCV * @see https://stackoverflow.com/questions/4641817/blob-extraction-in-opencv * @see http://voices.yahoo.com/connected-components-using-opencv-5462975.html?cat=15 * @see http://opencv.willowgarage.com/documentation/cpp/structural_analysis_and_shape_descriptors.html#cv-findcontours * @author happyburnout */ public class JavaCVBlobDemo { static String sourcePath = "c:/test/source.jpg"; static String targetPath = "c:/test/target.jpg"; public static void main (String args[]){ IplImage image = cvLoadImage(sourcePath); IplImage grayImage = cvCreateImage(cvGetSize(image), IPL_DEPTH_8U, 1); cvCvtColor(image, grayImage, CV_BGR2GRAY); CvMemStorage mem; CvSeq contours = new CvSeq(); CvSeq ptr = new CvSeq(); cvThreshold(grayImage, grayImage, 150, 255, CV_THRESH_BINARY); mem = cvCreateMemStorage(0); cvFindContours(grayImage, mem, contours, sizeof(CvContour.class) , CV_RETR_CCOMP, CV_CHAIN_APPROX_SIMPLE, cvPoint(0,0)); Random rand = new Random(); for (ptr = contours; ptr != null; ptr = ptr.h_next()) { Color randomColor = new Color(rand.nextFloat(), rand.nextFloat(), rand.nextFloat()); CvScalar color = CV_RGB( randomColor.getRed(), randomColor.getGreen(), randomColor.getBlue()); cvDrawContours(image, ptr, color, CV_RGB(0,0,0), -1, CV_FILLED, 8, cvPoint(0,0)); } cvSaveImage(targetPath, image); } } </code></pre>

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