jaitools.media.jai.kernel.KernelUtil Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of kernel Show documentation
Factory and utility classes to work with KernelJAI objects
There is a newer version: 1.0.1
/*
 * Copyright 2009 Michael Bedward
 *
 * This file is part of jai-tools.

 * jai-tools is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.

 * jai-tools is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.

 * You should have received a copy of the GNU Lesser General Public
 * License along with jai-tools.  If not, see .
 *
 */

package jaitools.media.jai.kernel;

import javax.media.jai.KernelJAI;

/**
 * Various utility methods that work with KernelJAI objects
 *
 * @author Michael Bedward
 * @since 1.0
 * @source $URL: https://jai-tools.googlecode.com/svn/tags/1.0.0/kernel/src/main/java/jaitools/media/jai/kernel/KernelUtil.java $
 * @version $Id: KernelUtil.java 531 2009-08-06 12:27:52Z michael.bedward $
 */
public class KernelUtil {

    /**
     * Create a copy of the input kernel with element values
     * standardized to sum to 1.0. The input kernel's
     * dimensions and location of the key element are retained
     * by the new kernel.
     *
     * @param kernel the input kernel
     * @return a new KernelJAI object
     */
    public static KernelJAI standardize(KernelJAI kernel) {
        float[] data = kernel.getKernelData();
        float sum = 0f;
        for (float f : data) {
            sum += f;
        }

        for (int i = 0; i < data.length; i++) {
            data[i] /= sum;
        }

        return new KernelJAI(
                kernel.getWidth(),
                kernel.getHeight(),
                kernel.getXOrigin(),
                kernel.getYOrigin(),
                data);
    }

    /**
     * A utility function that returns a string representation of
     * a KernelJAI object's data.
     *
     * @param kernel the input kernel
     * @param multiLine if true, each row of kernel data is followed by a newline;
     * if false, the string contains no newlines
     *
     * @return a String
     */
    public static String kernelToString(KernelJAI kernel, boolean multiLine) {
        float[] data = kernel.getKernelData();
        int w = kernel.getWidth();
        int h = kernel.getHeight();
        StringBuilder sb = new StringBuilder();

        boolean binaryData = true;
        for (int i = 0; i < data.length && binaryData; i++) {
            if (!(feq(data[i], 0) || feq(data[i], 1))) {
                binaryData = false;
            }
        }

        int k = 0;
        sb.append("[");
        for (int i = 0; i < w; i++) {
            sb.append("[");
            for (int j = 0; j < h; j++, k++) {
                if (binaryData) {
                    sb.append((int) data[k]);
                } else {
                    sb.append(String.format("%.4f", data[k]));
                    if (j < w-1) sb.append(" ");
                }
            }
            sb.append("]");
            if (i < w - 1) {
                if (multiLine) {
                    sb.append("\n ");
                } else {
                    sb.append(" ");
                }
            }
        }
        sb.append("]");

        return sb.toString();
    }

    // round-off tolerance: used in the fcomp method below
    private static final float TOL = 1.0e-8f;

    /**
     * Test if two float values are equal, taking into accont a
     * round-off tolerance
     * @param f1 first value
     * @param f2 second value
     * @return true if equal, false otherwise
     */
    private static boolean feq(float f1, float f2) {
        return Math.abs(f1 - f2) < TOL;
    }
}