algorithms.quality.ColorDivergenceVariance.java Source code

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Here is the source code for algorithms.quality.ColorDivergenceVariance.java

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/*
 * Copyright 2014 Fraunhofer IGD
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package algorithms.quality;

import java.awt.Color;
import java.awt.geom.Point2D;
import java.util.Iterator;

import org.apache.commons.math3.stat.descriptive.DescriptiveStatistics;

import algorithms.MedianDivergenceComputer;
import algorithms.sampling.SamplingStrategy;
import de.fhg.igd.iva.colormaps.Colormap;

/**
 * Computes the variance of the color distance/map distance ratio.
 * @author Martin Steiger
 */
public final class ColorDivergenceVariance implements ColormapQuality {
    private final SamplingStrategy strategy;

    public ColorDivergenceVariance(SamplingStrategy strategy) {
        this.strategy = strategy;
    }

    @Override
    public double getQuality(Colormap colormap) {
        DescriptiveStatistics stats = new DescriptiveStatistics();
        Iterator<Point2D> ptIt = strategy.getPoints().iterator();

        while (ptIt.hasNext()) {
            Point2D p1 = ptIt.next();

            if (!ptIt.hasNext())
                break;

            Point2D p2 = ptIt.next();

            double dist = p1.distance(p2);

            Color colorA = colormap.getColor(p1.getX(), p1.getY());
            Color colorB = colormap.getColor(p2.getX(), p2.getY());

            // roughly 0-100
            double cdist = MedianDivergenceComputer.colorDiff(colorA, colorB);

            double ratio = cdist / dist;

            stats.addValue(ratio);
        }

        return stats.getStandardDeviation();
    }

    @Override
    public boolean moreIsBetter() {
        return false;
    }

    @Override
    public String getName() {
        return "Dist. Ratio Divergence";
    }

    @Override
    public String getDescription() {
        return "The standard deviation of the color distance/map distance ratio";
    }
}