Good Day Guys,
I am detecting a paper by finding out biggest rectangle in an image which is performed by code given below which i found in the link [link text](http://stackoverflow.com/questions/8667818/opencv-c-obj-c-detecting-a-sheet-of-paper-square-detection/8863060#8863060). and[java code](http://stackoverflow.com/questions/18020455/java-opencv-tesseract-ocr-code-regocnition/18042054#18042054)
Image [link text](http://cl.ly/2o3V2g3l3f0e3m0s1p1K)
But still not able to retrive the found biggest rectangle the the image
import java.util.ArrayList;
import java.util.List;
import org.opencv.core.Core;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.core.MatOfInt;
import org.opencv.core.MatOfPoint;
import org.opencv.core.MatOfPoint2f;
import org.opencv.core.Point;
import org.opencv.core.Rect;
import org.opencv.core.Scalar;
import org.opencv.core.Size;
import org.opencv.highgui.Highgui;
import org.opencv.imgproc.Imgproc;
public class detection {
private static double angle(Point p1, Point p2, Point p0 ) {
double dx1 = p1.x - p0.x;
double dy1 = p1.y - p0.y;
double dx2 = p2.x - p0.x;
double dy2 = p2.y - p0.y;
return (dx1 * dx2 + dy1 * dy2) / Math.sqrt((dx1 * dx1 + dy1 * dy1) * (dx2 * dx2 + dy2 * dy2) + 1e-10);
}
private static MatOfPoint find(Mat src) throws Exception {
Mat blurred = src.clone();
Imgproc.medianBlur(src, blurred, 9);
Mat gray0 = new Mat(blurred.size(), CvType.CV_8U), gray = new Mat();
List contours = new ArrayList<>();
List blurredChannel = new ArrayList<>();
blurredChannel.add(blurred);
List gray0Channel = new ArrayList<>();
gray0Channel.add(gray0);
MatOfPoint2f approxCurve;
double maxArea = 0;
int maxId = -1;
for (int c = 0; c < 3; c++) {
int ch[] = {c, 0};
Core.mixChannels(blurredChannel, gray0Channel, new MatOfInt(ch));
int thresholdLevel = 1;
for (int t = 0; t < thresholdLevel; t++) {
if (t == 0) {
Imgproc.Canny(gray0, gray, 10, 20, 3, true); // true ?
Imgproc.dilate(gray, gray, new Mat(), new Point(-1, -1), 1); // 1 ?
} else {
Imgproc.adaptiveThreshold(gray0, gray, thresholdLevel, Imgproc.ADAPTIVE_THRESH_GAUSSIAN_C, Imgproc.THRESH_BINARY, (src.width() + src.height()) / 200, t);
}
Imgproc.findContours(gray, contours, new Mat(), Imgproc.RETR_LIST, Imgproc.CHAIN_APPROX_SIMPLE);
for (MatOfPoint contour : contours) {
MatOfPoint2f temp = new MatOfPoint2f(contour.toArray());
double area = Imgproc.contourArea(contour);
approxCurve = new MatOfPoint2f();
Imgproc.approxPolyDP(temp, approxCurve, Imgproc.arcLength(temp, true) * 0.02, true);
if (approxCurve.total() == 4 && area >= maxArea) {
double maxCosine = 0;
List curves = approxCurve.toList();
for (int j = 2; j < 5; j++)
{
double cosine = Math.abs(angle(curves.get(j % 4), curves.get(j - 2), curves.get(j - 1)));
maxCosine = Math.max(maxCosine, cosine);
}
if (maxCosine < 0.3) {
maxArea = area;
maxId = contours.indexOf(contour);
//contours.set(maxId, getHull(contour));
}
}
}
}
}
if (maxId >= 0) {
return contours.get(maxId);
//Imgproc.drawContours(src, contours, maxId, new Scalar(255, 0, 0, .8), 8);
}
return null;
}
public static void main(String args[]) throws Exception
{
System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
detection d=new detection();
Mat image=Highgui.imread("qwe.jpg");
Mat image1=new Mat();
MatOfPoint contour = d.find(image);
System.out.println(contour.size());
List contours = new ArrayList<>();
contours.add(contour);
for (int i = 0; i < contours.size(); i++) {
Imgproc.drawContours(image1, contours, 0, new Scalar(255, 255, 255), -1);
}
Highgui.imwrite("debug_image.jpg", image1);
//Highgui.imwrite("a.jpg", contour);
/* MatOfPoint2f approxCurve = new MatOfPoint2f();
//Imgproc.drawContours(image, contours, Core.FILLED, new Scalar(255, 255, 255));
MatOfPoint2f contour2f = new MatOfPoint2f( contours.get(0).toArray() );
//Processing on mMOP2f1 which is in type MatOfPoint2f
double approxDistance = Imgproc.arcLength(contour2f, true)*0.02;
Imgproc.approxPolyDP(contour2f, approxCurve, approxDistance, true);
//Convert back to MatOfPoint
MatOfPoint points = new MatOfPoint( approxCurve.toArray() );
// Get bounding rect of contour
Rect rect = Imgproc.boundingRect(points);
// draw enclosing rectangle (all same color, but you could use variable i to make them unique)
Core.rectangle(image, new Point(rect.x,rect.y), new Point(rect.x+rect.width,rect.y+rect.height),new Scalar(0,255,0));
Rect rect_crop = new Rect(rect.x-1, rect.y-1, rect.width+1, rect.height+1);
Mat image_roi = new Mat(image,rect_crop);
Highgui.imwrite("a.jpg",image_roi);
*/
}
}
Thanks
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