Opencv4Android grabcut's output image has different colors(brighter colors) than the input image

问题

public class Grabcut extends Activity {
ImageView iv;
Bitmap bitmap;
Canvas canvas;
Scalar color = new Scalar(255, 0, 0, 255);
Point tl, br;
int counter;
Bitmap bitmapResult, bitmapBackground;
Mat dst = new Mat();
final String pathToImage  = Environment.getExternalStorageDirectory()+"/gcut.png";
public static final String TAG = "Grabcut demo";
static {
      if (!OpenCVLoader.initDebug()) {
        // Handle initialization error
      }
    }
@Override
public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
    setContentView(R.layout.grabcut_main);
    iv = (ImageView) this.findViewById(R.id.imageView);


    Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.grabcut);
    Log.d(TAG, "bitmap: " + bitmap.getWidth() + "x" + bitmap.getHeight());


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


    //GrabCut part
    Mat img = new Mat();
    Utils.bitmapToMat(bitmap, img);
    Log.d(TAG, "img: " + img);

    int r = img.rows();
    int c = img.cols();

    Point p1 = new Point(c/5, r/5);
    Point p2 = new Point(c-c/5, r-r/8);

    Rect rect = new Rect(p1,p2);
    //Rect rect = new Rect(50,30, 100,200);
    Log.d(TAG, "rect: " + rect);

    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, 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, mask, Core.CMP_EQ);
    Mat foreground = new Mat(img.size(), CvType.CV_8UC3, new Scalar(255, 255, 255));
    img.copyTo(foreground, mask);
    Core.rectangle(img, p1, p2, color);

    Mat background = new Mat();
    try {
        background = Utils.loadResource(getApplicationContext(),
                R.drawable.wall2 );
    } 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 */);
    //Imgproc.threshold(tempMask, tempMask, 254, 255, 1 /* THRESH_BINARY_INV */);

    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);

    //convert to Bitmap
    Log.d(TAG, "Convert to Bitmap");
    Utils.matToBitmap(dst, bitmap);

    iv.setBackgroundResource(R.drawable.wall2);
    iv.setImageBitmap(bitmap);
    //release MAT part
    img.release();
    imgC3.release();
    mask.release();
    fgdModel.release();
    bgdModel.release();

}

public void debugger(String s){
    Log.v("","########### "+s);
}

}

I had followed above tutorial.But problem is that output image I get has brighter colors than my input image. Why is that and how to solve it? My input image is Here and output image is here.Output image is actually screenshot of my application where large one is input image and small one with black background is output image.

回答1:

I finally found solution to my problem. Here is code to grab cut background of an image using Grabcut algorithm in opencv for android.

public void grabcutAlgo(Bitmap bit){
    Bitmap b = bit.copy(Bitmap.Config.ARGB_8888, true);
    Point tl=new Point();
    Point br=new Point();
    //GrabCut part
    Mat img = new Mat();
    Utils.bitmapToMat(b, img);
    Imgproc.cvtColor(img, img, Imgproc.COLOR_RGBA2RGB);

    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);
    //Rect rect = new Rect(tl, br);
    Mat background = new Mat(img.size(), CvType.CV_8UC3,
            new Scalar(255, 255, 255));
    Mat firstMask = new Mat();
    Mat bgModel = new Mat();
    Mat fgModel = new Mat();
    Mat mask;
    Mat source = new Mat(1, 1, CvType.CV_8U, new Scalar(Imgproc.GC_PR_FGD));
    Mat dst = new Mat();


    Imgproc.grabCut(img, firstMask, rect, bgModel, fgModel, 5, Imgproc.GC_INIT_WITH_RECT);
    Core.compare(firstMask, source, firstMask, Core.CMP_EQ);

    Mat foreground = new Mat(img.size(), CvType.CV_8UC3, new Scalar(255, 255, 255));

    img.copyTo(foreground, firstMask);

    Scalar color = new Scalar(255, 0, 0, 255);
    Imgproc.rectangle(img, tl, br, color);

    Mat tmp = new Mat();
    Imgproc.resize(background, tmp, img.size());
    background = tmp;
    mask = new Mat(foreground.size(), CvType.CV_8UC1,
            new Scalar(255, 255, 255));

    Imgproc.cvtColor(foreground, mask, Imgproc.COLOR_BGR2GRAY);
    Imgproc.threshold(mask, mask, 254, 255, Imgproc.THRESH_BINARY_INV);
    System.out.println();
    Mat vals = new Mat(1, 1, CvType.CV_8UC3, new Scalar(0.0));
    background.copyTo(dst);

    background.setTo(vals, mask);

    Core.add(background, foreground, dst, mask);
    Bitmap grabCutImage = Bitmap.createBitmap(dst.cols(), dst.rows(), Bitmap.Config.ARGB_8888);
    Bitmap processedImage = Bitmap.createBitmap(dst.cols(), dst.rows(), Bitmap.Config.RGB_565);
    Utils.matToBitmap(dst, grabCutImage);
    dst.copyTo(sampleImage);
    imageView.setImageBitmap(grabCutImage);
    firstMask.release();
    source.release();
    bgModel.release();
    fgModel.release();
}

来源：https://stackoverflow.com/questions/50076708/opencv4android-grabcuts-output-image-has-different-colorsbrighter-colors-than