alokitnigam's profile - activity

Good day guys,

currently I am working on developing an android app which finds the biggest rectangle in camera preview in run time(To detect a page or a rectangular object) and perform OCR to it. I have problem in detecting image in run time. It shows the following error.

FATAL EXCEPTION: main Process: sansys.helpinghands, PID: 978 CvException [org.opencv.core.CvException: cv::Exception: /Volumes/Linux/builds/master_pack-android/opencv/modules/imgproc/src/color.cpp:8282: error: (-215) sz.width % 2 == 0 && sz.height % 3 == 0 && depth == CV_8U in function void cv::cvtColor(cv::InputArray, cv::OutputArray, int, int) ] at org.opencv.imgproc.Imgproc.cvtColor_0(Native Method) at org.opencv.imgproc.Imgproc.cvtColor(Imgproc.java:1715) at sansys.helpinghands.CameraPreview.processFrame(CameraPreview.java:201) at sansys.helpinghands.CameraPreview.onPreviewFrame(CameraPreview.java:65) at android.hardware.Camera$EventHandler.handleMessage(Camera.java:1129) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5443) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:728) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)

I have presented my code below.

Thanks

Camera preview class

public class CameraPreview implements SurfaceHolder.Callback, Camera.PreviewCallback {
private Camera mCamera = null;
private ImageView MyCameraPreview = null;
private Bitmap bitmap,bmp = null;
private int[] pixels = null;
private byte[] FrameData = null;
private int imageFormat;
private int PreviewSizeWidth;
private int PreviewSizeHeight;
private boolean bProcessing = false;
private Mat mYuv;

Handler mHandler = new Handler(Looper.getMainLooper());

public CameraPreview(int PreviewlayoutWidth, int PreviewlayoutHeight,
                     ImageView CameraPreview) {
    PreviewSizeWidth = PreviewlayoutWidth;
    PreviewSizeHeight = PreviewlayoutHeight;
    MyCameraPreview = CameraPreview;
    mYuv = new Mat(PreviewlayoutHeight+PreviewlayoutWidth / 2, PreviewlayoutWidth, CvType.CV_8UC1);
    Log.v("-------------------->",""+mYuv.channels());


    pixels = new int[PreviewSizeWidth * PreviewSizeHeight];
}

@Override
public void onPreviewFrame(byte[] arg0, Camera arg1) {
    // At preview mode, the frame data will push to here.
    if (imageFormat == ImageFormat.NV21) {
        //We only accept the NV21(YUV420) format.
        if (!bProcessing) {
            FrameData = arg0;
            this.processFrame(arg0);
            bmp=processFrame(arg0);

            mHandler.post(DoImageProcessing);
        }
    }
}

public void onPause() {
    mCamera.stopPreview();
}

@Override
public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) {
    Camera.Parameters parameters;

    parameters = mCamera.getParameters();
    // Set the camera preview size
    parameters.setPreviewSize(PreviewSizeWidth, PreviewSizeHeight);

    imageFormat = parameters.getPreviewFormat();

    mCamera.setParameters(parameters);

    mCamera.startPreview();
}

@Override
public void surfaceCreated(SurfaceHolder arg0) {
    mCamera = Camera.open();
    try {
        // If did not set the SurfaceHolder, the preview area will be black.
        mCamera.setPreviewDisplay(arg0);
        mCamera.setPreviewCallback(this);
    } catch (IOException e) {
        mCamera.release();
        mCamera = null;
    }
}

@Override
public void surfaceDestroyed(SurfaceHolder arg0) {
    mCamera.setPreviewCallback(null);
    mCamera.stopPreview();
    mCamera.release();
    mCamera = null;
}


static {
    System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
}

private Runnable DoImageProcessing = new Runnable() {
    public void run() {

        System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
        // Mat mat = Imgcodecs.imdecode(new MatOfByte(FrameData), Imgcodecs.CV_LOAD_IMAGE_UNCHANGED);
        Mat tmp = new Mat(bitmap.getHeight(), bitmap.getWidth(), CvType.CV_8UC3);
        bitmap = Bitmap.createBitmap(PreviewSizeWidth, PreviewSizeHeight, Bitmap.Config.ARGB_8888);
        Log.i("MyRealTimeImageProcess", "DoImageProcessing():");
        bProcessing = true;

        bitmap.sameAs(bmp);
        Utils.bitmapToMat(bitmap, tmp);
        Log.v("qweedfdfbfdbf",tmp.width()+""+tmp.height());
        // detection d = new detection(PreviewSizeWidth, PreviewSizeHeight, FrameData, pixels);
        detection d = new detection();
        MatOfPoint point = null;
        try {
            point ...

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. andjava code Image link text 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<MatOfPoint> contours = new ArrayList<>();

        List<Mat> blurredChannel = new ArrayList<>();
        blurredChannel.add(blurred);
        List<Mat> 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<Point> 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<MatOfPoint> 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 ...