Comment mettre une image de masque pour grabCut dans OpenCV?

Exemple de travail dans OpenCV:

//Fill with the background value
Mat mask = cv::Mat::ones(src.size(), CV_8U) * cv::GC_BGD;

//Fill a smaller rectangle with the probably-foreground value.
Rect area;
area.x=10;  area.y=10;
area.width=250; area.height=250;
rectangle(mask, area , cv::Scalar(cv::GC_PR_FGD),-1,8,0);

//Fill a smaller rectangle with the foreground value.
area.x=50;  area.y=50;
area.width=20;  area.height=20;
rectangle(mask, area , cv::Scalar(cv::GC_FGD),-1,8,0);

Mat bgd,fgd;
cv::grabCut(src, mask, area, bgd, fgd, 1, cv::GC_INIT_WITH_MASK);

//Visualize results.
compare(mask,cv::GC_FGD,mask,cv::CMP_EQ);
Mat foreground(src.size(),CV_8UC3, cv::Scalar(0,0,0));
src.copyTo(foreground,mask);
imshow("segm",foreground);

OriginalL'auteur William

Les images de l'entrée (lena.png, lena_mask.png):

Code (JAVA):

import org.opencv.core.Core;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.core.Rect;
import org.opencv.core.Scalar;
import org.opencv.highgui.Highgui;
import org.opencv.imgproc.Imgproc;

/**
 * Example how to use grabCut algorithm in OpenCV using GC_INIT_WITH_MASK.
 *
 */
public class ImageSegmentByMask {

    public static void main(String[] args) {
        System.loadLibrary(Core.NATIVE_LIBRARY_NAME);

        //will read image
        Mat image = Highgui.imread("lena.png");
        Mat mask = Highgui.imread("lena_mask.png", Highgui.CV_LOAD_IMAGE_GRAYSCALE);

        Rect rectangle = new Rect(10, 10, image.cols() - 20, image.rows() - 20);

        Mat bgdModel = new Mat(); //extracted features for background
        Mat fgdModel = new Mat(); //extracted features for foreground
        Mat source = new Mat(1, 1, CvType.CV_8U, new Scalar(0));

        convertToOpencvValues(mask); //from human readable values to OpenCV values 

        int iterCount = 1;
        Imgproc.grabCut(image, mask, rectangle, bgdModel, fgdModel, iterCount, Imgproc.GC_INIT_WITH_MASK);


        convertToHumanValues(mask); //back to human readable values
        Imgproc.threshold(mask,mask,128,255,Imgproc.THRESH_TOZERO);

        Mat foreground = new Mat(image.size(), CvType.CV_8UC1, new Scalar(0, 0, 0));
        image.copyTo(foreground, mask);

        Highgui.imwrite("sandbox/sucess1.jpg", foreground);
    }

    private static void convertToHumanValues(Mat mask) {
        byte[] buffer = new byte[3];
        for (int x = 0; x < mask.rows(); x++) {
            for (int y = 0; y < mask.cols(); y++) {
                mask.get(x, y, buffer);
                int value = buffer[0];
                if (value == Imgproc.GC_BGD) {
                    buffer[0] = 0; //for sure background
                } else if (value == Imgproc.GC_PR_BGD) {
                    buffer[0] = 85; //probably background
                } else if (value == Imgproc.GC_PR_FGD) {
                    buffer[0] = (byte) 170; //probably foreground
                } else {
                    buffer[0] = (byte) 255; //for sure foreground

                }
                mask.put(x, y, buffer);
            }
        }
    }

    /**
     * Converts level of grayscale into OpenCV values. White - foreground, Black
     * - background.
     * 
     * @param mask
     */
    private static void convertToOpencvValues(Mat mask) {
        byte[] buffer = new byte[3];
        for (int x = 0; x < mask.rows(); x++) {
            for (int y = 0; y < mask.cols(); y++) {
                mask.get(x, y, buffer);
                int value = buffer[0];
                if (value >= 0 && value < 64) {
                    buffer[0] = Imgproc.GC_BGD; //for sure background
                } else if (value >= 64 && value < 128) {
                    buffer[0] = Imgproc.GC_PR_BGD; //probably background
                } else if (value >= 128 && value < 192) {
                    buffer[0] = Imgproc.GC_PR_FGD; //probably foreground
                } else {
                    buffer[0] = Imgproc.GC_FGD; //for sure foreground

                }
                mask.put(x, y, buffer);
            }
        }

    }

}

Résultat:

OriginalL'auteur Radim Burget