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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libjava/] [classpath/] [gnu/] [java/] [awt/] [color/] [GrayScaleConverter.java] - Blame information for rev 769

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1 769 jeremybenn
/* GrayScaleConverter.java -- Linear grayscale conversion class
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   Copyright (C) 2004 Free Software Foundation
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING.  If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library.  Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module.  An independent module is a module which is not derived from
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or based on this library.  If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so.  If you do not wish to do so, delete this
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exception statement from your version. */
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package gnu.java.awt.color;
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/**
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 * Linear Grayscale converter
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 *
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 * @author Sven de Marothy
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 */
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public class GrayScaleConverter implements ColorSpaceConverter
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{
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  // intensity factors (ITU Rec. BT.709)
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  double[] coeff = { 0.2125f, 0.7154f, 0.0721f };
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  /**
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   * CIE 1931 D50 white point (in Lab coordinates)
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   */
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  private static float[] D50 = { 0.96422f, 1.00f, 0.82521f };
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  public float[] toCIEXYZ(float[] in)
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  {
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    float g = in[0];
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    if (g < 0)
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      g = 1 + g;
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    float[] out = { g * D50[0], g * D50[1], g * D50[2] }; // White spot
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    return out;
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  }
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  public float[] toRGB(float[] in)
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  {
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    float[] out = new float[3];
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    if (in[0] <= 0.00304f)
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      out[0] = in[0] * 12.92f;
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    else
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      out[0] = 1.055f * ((float) Math.exp((1 / 2.4) * Math.log(in[0])))
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               - 0.055f;
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    out[1] = out[2] = out[0];
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    return out;
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  }
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  public float[] fromCIEXYZ(float[] in)
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  {
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    float[] temp = new float[3];
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    temp[0] = 3.1338f * in[0] - 1.6171f * in[1] - 0.4907f * in[2];
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    temp[1] = -0.9785f * in[0] + 1.9160f * in[1] + 0.0334f * in[2];
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    temp[2] = 0.0720f * in[0] - 0.2290f * in[1] + 1.4056f * in[2];
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    float[] out = new float[1];
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    for (int i = 0; i < 3; i++)
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      out[0] = (float) (temp[i] * coeff[i]);
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    return out;
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  }
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  public float[] fromRGB(float[] in)
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  {
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    float[] out = new float[1];
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    // Convert non-linear RGB coordinates to linear ones,
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    //  numbers from the w3 spec.
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    out[0] = 0;
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    for (int i = 0; i < 3; i++)
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      {
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        float n = in[i];
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        if (n < 0)
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          n = 0f;
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        if (n > 1)
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          n = 1f;
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        if (n <= 0.03928f)
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          out[0] += (float) (coeff[i] * n / 12.92);
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        else
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          out[0] += (float) (coeff[i] * Math.exp(2.4 * Math.log((n + 0.055) / 1.055)));
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      }
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    return out;
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  }
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}

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