图像处理之计算连通区域的角度方向

package com.gloomyfish.image.moments;
 
import java.awt.image.BufferedImage;
 
import com.gloomyfish.filter.study.AbstractBufferedImageOp;
import com.gloomyfish.rice.analysis.FastConnectedComponentLabelAlg;
 
public class DirectionRegionMoments extends AbstractBufferedImageOp {
 
  @Override
  public BufferedImage filter(BufferedImage src, BufferedImage dest) {
    int width = src.getWidth();
        int height = src.getHeight();
 
        if ( dest == null )
          dest = createCompatibleDestImage( src, null );
 
        // first step - make it as binary image output pixel
        int[] inPixels = new int[width*height];
        int[] outPixels = new int[width*height];
        getRGB( src, 0, 0, width, height, inPixels );
        int index = 0;
        for(int row=0; row<height; row++) {
          int tr = 0;
          for(int col=0; col<width; col++) {
            index = row * width + col;
                tr = (inPixels[index] >> 16) & 0xff;
                if(tr > 127)
                {
                   outPixels[index] = 1;
                }
                else
                {
                  outPixels[index] = 0;
                }
          }
        }
        
        // second step, connected component labeling algorithm
        FastConnectedComponentLabelAlg ccLabelAlg = new FastConnectedComponentLabelAlg();
        ccLabelAlg.setBgColor(0);
        int[] labels = ccLabelAlg.doLabel(outPixels, width, height);
        int max = 0;
        for(int i=0; i<labels.length; i++)
        {
          if(max < labels[i])
          {
            System.out.println("Label Index = " + labels[i]);
            max = labels[i];
          }
        }
        
        // third step, calculate the orientation of the region
        int[] input = new int[labels.length];
        GeometricMomentsAlg momentsAlg = new GeometricMomentsAlg();
        momentsAlg.setBACKGROUND(0);
        double[][] labelCenterPos = new double[max][2];
        double[][] centerAngles = new double[max][3];
        for(int i=1; i<=max; i++)
        {
          int numberOfLabel = 0;
          for(int p=0; p<input.length; p++)
          {
            if(labels[p] == i)
            {
              input[p] = labels[p];  
              numberOfLabel++;
            }
            else
            {
              input[p] = 0;
            }
          }
          labelCenterPos[i-1] = momentsAlg.getGeometricCenterCoordinate(input, width, height);
          double m11 = momentsAlg.centralMoments(input, width, height, 1, 1);
          double m02 = momentsAlg.centralMoments(input, width, height, 0, 2);
          double m20 = momentsAlg.centralMoments(input, width, height, 2, 0);
          double m112 = m11 * m11;
          double dd = Math.pow((m20-m02), 2);
          double sum1 = Math.sqrt(dd + 4*m112);
          double sum2 = m02 + m20;
          double a1 = sum2 + sum1;
          double a2 = sum2 - sum1;
          // double ecc = a1 / a2;
          
          double ra = Math.sqrt((2*a1)/Math.abs(numberOfLabel));
          double rb = Math.sqrt((2*a2)/Math.abs(numberOfLabel));
          double angle = Math.atan((2*m11)/(m20 - m02))/2.0;
          centerAngles[i-1][0] = angle;
          centerAngles[i-1][1] = ra;
          centerAngles[i-1][2] = rb;
        }
        
        
        // render the angle/orientation info for each region
        // render the each connected component center position
        for(int row=0; row<height; row++) {
          for(int col=0; col<width; col++) {
            index = row * width + col;
            if(labels[index] == 0)
            {
              outPixels[index] = (255 << 24) | (0 << 16) | (0 << 8) | 0; // make it as black for background
            }
            else
            {
              outPixels[index] = (255 << 24) | (0 << 16) | (0 << 8) | 100; // make it as blue for each region area
            }
          }
        }
        
        int labelCount = centerAngles.length;
        for(int i=0; i<labelCount; i++)
        {
          System.out.println("Region " + i + "'s angle = " + centerAngles[i][0]);
          System.out.println("Region " + i + " ra = " + centerAngles[i][1]);
          System.out.println("Region " + i + " rb = " + centerAngles[i][2]);
          double sin = Math.sin(centerAngles[i][0]);
          double cos = Math.cos(centerAngles[i][0]);
          System.out.println("sin = " + sin);
          System.out.println("cos = " + cos);
          System.out.println();
          int crow = (int)labelCenterPos[i][0];
          int ccol = (int)labelCenterPos[i][1];
          int radius = (int)centerAngles[i][1]; // ra
          for(int j=0; j<radius; j++)
          {
            int drow = (int)(crow - j * sin); // it is trick, display correct angle as you see!!!
            int dcol = (int)(ccol + j * cos);
            if(drow >= height) continue;
            if(dcol >= width) continue;
            index = drow * width + dcol;
              outPixels[index] = (255 << 24) | (255 << 16) | (255 << 8) | 0; 
          }
        }
        
        // make it as white color for each center position
        for(int i=0; i<max; i++)
        {
          int crow = (int)labelCenterPos[i][0];
          int ccol = (int)labelCenterPos[i][1];
          index = crow * width + ccol;
          outPixels[index] = (255 << 24) | (255 << 16) | (255 << 8) | 255; 
        }
        
        setRGB( dest, 0, 0, width, height, outPixels );
    return dest;
  }
 
}