如何在OpenCV中爲grabCut設置遮罩圖像？

Question

如何在OpenCV中爲grabCut功能設置遮罩圖像？ 我想做GC_INIT_WITH_MASK與選項

GC_BGD = 0, 
GC_FGD = 1, 
GC_PR_BGD = 2, 
GC_PR_FGD = 3, 

如果你可以用JavaCV回答這個問題，因爲我在斯卡拉/ Java的這樣做，這將是巨大的。

Answer 1

初始圖像掩模的第二個參數grabCut，所以你應該只能夠與CvMat.create()創建一個圖像，然後適當地設定的值，以GC_BGD, GC_FGC, GC_PR_BGD, GC_PR_FGD，例如（不能夠在該計算機上測試代碼）：

val mask = cvCreateImage(cvGetSize(image), IPL_DEPTH_8U, 1) 
// Set mask pixel values to what you want 
mask.put(offset, GC_BGD) 
... 
grabCut(image, mask, ... <your other options here>) 

我不是最熟悉javacv，有可能是在設定範圍或塊的值的面具，而不是一次一個像素一個好辦法。

此外，根據docs爲grabCut：

Answer 2

「注意GC_INIT_WITH_RECT和GC_INIT_WITH_MASK可以結合， 那麼所有的ROI之外的像素被自動與GC_BGD初始化 」

OpenCV中的工作示例：

//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); 

Answer 3

public class ImageSegment { 

    public static void main(String[] args) { 
     System.loadLibrary("opencv_java244"); 

     Mat image = null; 
     image = Highgui.imread("syh.jpg"); 

     Rect rectangle = new Rect(25,25,image.cols()-64,image.rows()-64); 
     Mat result = new Mat(); 
     Mat bgdModel = new Mat(); 
     Mat fgdModel = new Mat(); 
     Mat source = new Mat(1, 1, CvType.CV_8U, new Scalar(3)); 
     Imgproc.grabCut(image, result, rectangle, bgdModel, fgdModel, 1, 0); 
     Core.compare(result, source,result, Core.CMP_EQ); 
     Mat foreground= new Mat(image.size(), CvType.CV_8UC1, new Scalar(0, 0, 0)); 
     image.copyTo(foreground, result); 
     Highgui.imwrite("sucess1.jpg", foreground); 
     System.out.println("grabcut sucess!"); 
    } 

} 

Answer 4

輸入圖像（lena.png，lena_mask.png）：

代碼（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); 
      } 
     } 

    } 

} 

結果：