/**
 * Java Modular Image Synthesis Toolkit (JMIST)
 * Copyright (C) 2008-2013 Bradley W. Kimmel
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */
package ca.eandb.jmist.framework.tone;

import ca.eandb.jmist.framework.color.CIEXYZ;

/**
 * @author Brad
 *
 */
public final class ReinhardToneMapperFactory implements ToneMapperFactory {

	/** Serialization version ID. */
	private static final long serialVersionUID = -8014074363504189066L;

	private static final double DEFAULT_DELTA = 1.0;

	private final double delta;

	public ReinhardToneMapperFactory(double delta) {
		this.delta = delta;
	}

	public ReinhardToneMapperFactory() {
		this(DEFAULT_DELTA);
	}

	/* (non-Javadoc)
	 * @see ca.eandb.jmist.framework.color.ToneMapperFactory#createToneMapper(java.lang.Iterable)
	 */
	public ToneMapper createToneMapper(Iterable<CIEXYZ> samples) {
		double Yavg = 0.0;
		double Ymax = 0.0;
		int n = 0;
		for (CIEXYZ sample : samples) {
			if (sample != null) {
				double Y = sample.Y();
				if (Y > Ymax) {
					Ymax = Y;
				}
				Yavg += Math.log(delta + Y);
				n++;
			}
		}
		Yavg /= (double) n;
		Yavg = Math.exp(Yavg) - delta;

		double Ymid = 1.03 - 2.0 / (2.0 + Math.log10(Yavg + 1.0));
		return new ReinhardToneMapper(Ymid / Yavg, Ymax);
	}

}

/**
 * Java Modular Image Synthesis Toolkit (JMIST)
 * Copyright (C) 2008-2013 Bradley W. Kimmel
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */
package ca.eandb.jmist.framework.tone;

import ca.eandb.jmist.framework.color.CIEXYZ;
import ca.eandb.jmist.math.MathUtil;

/**
 * @author Brad
 *
 */
public final class ReinhardToneMapperFactory implements ToneMapperFactory {

	/** Serialization version ID. */
	private static final long serialVersionUID = -8014074363504189066L;

	private static final double DEFAULT_KEY = 0.18;

	private static final double DEFAULT_DELTA = MathUtil.EPSILON;

	private final double key;

	private final double delta;

	public ReinhardToneMapperFactory(double key, double delta) {
		this.key = key;
		this.delta = delta;
	}

	public ReinhardToneMapperFactory() {
		this(DEFAULT_KEY, DEFAULT_DELTA);
	}

	/* (non-Javadoc)
	 * @see ca.eandb.jmist.framework.color.ToneMapperFactory#createToneMapper(java.lang.Iterable)
	 */
	public ToneMapper createToneMapper(Iterable<CIEXYZ> samples) {
		double Yavg = 0.0;
		double Ymax = 0.0;
		int n = 0;
		for (CIEXYZ sample : samples) {
			if (sample != null) {
				double Y = sample.Y();
				if (Y > Ymax) {
					Ymax = Y;
				}
				Yavg += Math.log(delta + Y);
				n++;
			}
		}
		Yavg /= (double) n;
		Yavg = Math.exp(Yavg) - delta;

		return new ReinhardToneMapper(key / Yavg, Ymax);
	}

}

Fix Y-scale calc for ReinhardToneMapperFactory