/*
 * Copyright (c) 2015, Harald Kuhr
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * * Redistributions of source code must retain the above copyright notice, this
 *   list of conditions and the following disclaimer.
 *
 * * Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 *
 * * Neither the name of the copyright holder nor the names of its
 *   contributors may be used to endorse or promote products derived from
 *   this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package com.twelvemonkeys.imageio.plugins.hdr.tonemap;

/**
 * GammaToneMapper.
 * <p>
 * Normalizes values to range [0...1] using:
 * </p>
 * <p>
 *     <em>V<sub>out</sub> = A V<sub>in</sub><sup>\u03b3</sup></em>
 * </p>
 * <p>
 * Where <em>A</em> is constant and <em>\u03b3</em> is the gamma.
 * Values &gt; 1 are clamped.
 * </p>
 *
 * @author <a href="mailto:harald.kuhr@gmail.com">Harald Kuhr</a>
 * @author last modified by $Author: harald.kuhr$
 * @version $Id: GammaToneMapper.java,v 1.0 28/07/15 harald.kuhr Exp$
 */
public final class GammaToneMapper implements ToneMapper {

    private final float constant;
    private final float gamma;

    public GammaToneMapper() {
        this(0.5f, .25f);
    }

    public GammaToneMapper(final float constant, final float gamma) {
        this.constant = constant;
        this.gamma = gamma;
    }

    @Override
    public void map(final float[] rgb) {
        // Gamma Vo = A * Vi^y
        for (int i = 0; i < rgb.length; i++) {
            rgb[i] = Math.min(1f, (float) (constant * Math.pow(rgb[i], gamma)));
        }
    }
}
