YoungBendingEnergy.java

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package theba.descriptors;

import java.util.ArrayList;

import theba.core.ImageFunctions;
import theba.core.RegionDescriptor;
import theba.core.RegionMask;


public class YoungBendingEnergy implements RegionDescriptor {

        public Object measure(RegionMask vmask) {
                short[] mask = new short[vmask.getWidth() * vmask.getHeight()];
                for (int x = 0; x < vmask.getWidth(); x++)
                        for (int y = 0; y < vmask.getHeight(); y++)
                                if (vmask.isSet(x, y, 0))
                                        mask[x + y * vmask.getWidth()] = 1;
                return measure(mask, vmask.getWidth(), vmask.getHeight());
        }

        public double measure(short[] pixels, int width, int height) {
                ArrayList points = ImageFunctions.borderTrace(pixels, width, height);
                int[] chaincode = ImageFunctions.getChaincode(points);
                double[] s = ImageFunctions.getArcLenghts(chaincode);
                if (s == null)
                        return -1; // return error, -1 is an impossible value

                double bendingEnergy = 0;
                for (int i = 1; i < s.length; i++) {
                        bendingEnergy += Math.pow((chaincode[i] - chaincode[i - 1])
                                        / (s[i] - s[i - 1]), 2);
                }
                return bendingEnergy / (s.length - 1);
        }

        public String getName() {
                return "Young Bending Energy";
        }

        public String getAbout() {
                return "Returns the average Young-curvature of a 4-connected 2D region";
        }

        public boolean does3D() {
                return false;
        }

        public boolean isNumeric() {
                return true;
        }

}