EccentricityDescriptor.java

Go to the documentation of this file.

package theba.descriptors;

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

public class EccentricityDescriptor 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) {

                double m_0_0 = 0, m_1_0 = 0, m_0_1 = 0;

                for (int x = 0; x < width; x++) {
                        for (int y = 0; y < height; y++) {
                                int index = x + y * width;
                                if (pixels[index] != 0) {
                                        m_0_0 += 1;
                                        m_1_0 += x;
                                        m_0_1 += y;
                                }
                        }
                }

                double x_c = m_1_0 / m_0_0;
                double y_c = m_0_1 / m_0_0;
                double m_0_2 = 0, m_2_0 = 0, m_1_1 = 0;
                for (int x = 0; x < width; x++) {
                        for (int y = 0; y < height; y++) {
                                int index = x + y * width;
                                if (pixels[index] != 0) {
                                        m_1_1 += (x - x_c) * (y - y_c);
                                        m_2_0 += (x - x_c) * (x - x_c);
                                        m_0_2 += (y - y_c) * (y - y_c);
                                }
                        }
                }

                double factor = m_2_0
                                + m_0_2
                                + Math.sqrt((m_2_0 - m_0_2) * (m_2_0 - m_0_2) + 4 * m_1_1
                                                * m_1_1);
                double dividend = m_2_0
                                + m_0_2
                                - Math.sqrt((m_2_0 - m_0_2) * (m_2_0 - m_0_2) + 4 * m_1_1
                                                * m_1_1);

                return factor / dividend;
        }

        public String getName() {
                return "Eccentricity";
        }

        public String getAbout() {
                return "Returns the eccentricity of a single 2D region";
        }

        public boolean does3D() {
                return false;
        }

        public boolean isNumeric() {
                return true;
        }

}