Edge refinement OpenCV android

Question

ok so I am a newbie to opencv, I have manage to perform a grabcut which seems "ok" to me except the edges are pretty out of shape, I want to get realistic edges, maybe blur the edges out to get a perfectly done image, another thing I have noticed is the colors tend to be too bright after the entire process I wanted to reduce the vibrancy to somewhat acceptable below is my code

private Bitmap backGrndErase()
{

    color = new Scalar(255, 0, 0, 255);
    dst = new Mat();
    Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.myshirt);
    Log.d(TAG, "bitmap: " + bitmap.getWidth() + "x" + bitmap.getHeight());


    bitmap = ResizeImage.getResizedBitmap(bitmap, calculatePercentage(40, bitmap.getWidth()), calculatePercentage(40, bitmap.getHeight()));



    bitmap = bitmap.copy(Bitmap.Config.ARGB_8888, true);
    Log.d(TAG, "bitmap 8888: " + bitmap.getWidth() + "x" + bitmap.getHeight());



    Mat img = new Mat();
    Utils.bitmapToMat(bitmap, img);


    Point p1 = new Point((img.cols()/10), (img.rows()/10));
    Point p2 = new Point((img.cols()-img.cols()/10), (img.rows()-img.rows()/10));
    Rect rect = new Rect(p1,p2);

    int border = 20;
    int border2 = border + border;
    Rect rect2 = new Rect( border, border, img.cols() - border2, img.rows()-border2);




    Mat mask = new Mat();
    debugger(""+mask.type());
    mask.setTo(new Scalar(125));
    Mat fgdModel = new Mat();
    fgdModel.setTo(new Scalar(255, 255, 255));
    Mat bgdModel = new Mat();
    bgdModel.setTo(new Scalar(255, 255, 255));

    Mat imgC3 = new Mat();
    Imgproc.cvtColor(img, imgC3, Imgproc.COLOR_RGBA2RGB);
    Log.d(TAG, "imgC3: " + imgC3);
    Log.d(TAG, "Grabcut begins");
    Imgproc.grabCut(imgC3, mask, rect2, bgdModel, fgdModel, 2, Imgproc.GC_INIT_WITH_RECT);
    Mat source = new Mat(1, 1, CvType.CV_8U, new Scalar(3.0));
    //Do Sth
    Core.compare(mask, source, mask, Core.CMP_EQ);
    //Do Sth
    Mat foreground = new Mat(img.size(), CvType.CV_8UC3, new Scalar(255, 255, 255));
    img.copyTo(foreground, mask);
    Imgproc.rectangle(img, p1, p2, color);

    Mat background = new Mat();
    try {
        background = Utils.loadResource(getApplicationContext(),
                R.drawable.blackcolor );
    } catch (IOException e) {

        e.printStackTrace();
    }
    Mat tmp = new Mat();
    Imgproc.resize(background, tmp, img.size());

    background = tmp;

    Mat tempMask = new Mat(foreground.size(), CvType.CV_8UC1, new Scalar(255, 255, 255));
    Imgproc.cvtColor(foreground, tempMask, 6/* COLOR_BGR2GRAY */);


    Mat vals = new Mat(1, 1, CvType.CV_8UC3, new Scalar(0.0));
    dst = new Mat();
    background.setTo(vals, tempMask);
    Imgproc.resize(foreground, tmp, mask.size());
    foreground = tmp;
    Core.add(background, foreground, dst, tempMask);
    Log.d(TAG, "Convert to Bitmap");


    //removing blackbaground started

     Mat tmp2 = new Mat();
     Mat alpha = new Mat();
     Imgproc.cvtColor(dst, tmp2, Imgproc.COLOR_BGR2GRAY);
     Imgproc.threshold(tmp2, alpha, 100, 255, Imgproc.THRESH_BINARY);


     List<Mat> rgb = new ArrayList<Mat>(3);
     Core.split(dst, rgb);


     List<Mat> rgba = new ArrayList<Mat>(4);
     rgba.add(rgb.get(0));
     rgba.add(rgb.get(1));
     rgba.add(rgb.get(2));
     rgba.add(alpha);
     Core.merge(rgba, dst);
     Bitmap output = Bitmap.createBitmap(dst.width(), dst.height(), Bitmap.Config.ARGB_8888);
     Utils.matToBitmap(dst, output);

    //removing back ended


    Utils.matToBitmap(dst, bitmap);



    //release MAT part
    img.release();
    imgC3.release();
    mask.release();
    fgdModel.release();
    bgdModel.release();
    alreadyRun = true;
    return  bitmap;

}

I have posted the same question on the opencv site but there seems to be low audience there compared to here, images

Answer 1

Try this code. It working for me

public Bitmap removeBackground(Bitmap bitmap) {
    //GrabCut part
    Mat img = new Mat();
    Utils.bitmapToMat(bitmap, img);

    int r = img.rows();
    int c = img.cols();
    Point p1 = new Point(c / 100, r / 100);
    Point p2 = new Point(c - c / 100, r - r / 100);
    Rect rect = new Rect(p1, p2);

    Mat mask = new Mat();
    Mat fgdModel = new Mat();
    Mat bgdModel = new Mat();

    Mat imgC3 = new Mat();
    Imgproc.cvtColor(img, imgC3, Imgproc.COLOR_RGBA2RGB);

    Imgproc.grabCut(imgC3, mask, rect, bgdModel, fgdModel, 5, Imgproc.
            GC_INIT_WITH_RECT);

    Mat source = new Mat(1, 1, CvType.CV_8U, new Scalar(3.0));
    Core.compare(mask, source/* GC_PR_FGD */, mask, Core.CMP_EQ);

    //This is important. You must use Scalar(255,255, 255,255), not Scalar(255,255,255)
    Mat foreground = new Mat(img.size(), CvType.CV_8UC3, new Scalar(255,
            255, 255,255));
    img.copyTo(foreground, mask);

    // convert matrix to output bitmap
    bitmap = Bitmap.createBitmap((int) foreground.size().width,
            (int) foreground.size().height,
            Bitmap.Config.ARGB_8888);
    Utils.matToBitmap(foreground, bitmap);
    return bitmap;
}

Answer 2

If you want to detect the edges or corners very precicely opencv has a set o subpixel resolution tools, and it could be a good idea to apply a gaussianFilter before the edge detection, that erase some undesirable noise

Answer 3

a trial code just to show some possibilities around your question ( assuming the background will be always white )

#include "opencv2/opencv.hpp"

using namespace cv;

int main(int argc, char** argv)
{
Mat src= imread( argv[1] );
Mat original = src.clone();

imshow("source", src);

src = src + Scalar(40,40,40); // to remove jpeg artifacts

Mat mask;
cvtColor( src, mask, COLOR_BGR2GRAY );

mask = mask < 255;

add(src,Scalar(0,60,20),src,mask);

Mat blackbg = Mat::zeros(src.size(),CV_8UC3);
original.copyTo( blackbg, mask);

imshow("mask", mask);
imshow("changed color", src);
imshow("original image with black background", blackbg);
waitKey();

return 0;
}