001/* ICC_ProfileGray.java -- the ICC profile for a Gray colorspace
002   Copyright (C) 2002, 2004 Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038
039package java.awt.color;
040
041/**
042 * ICC_ProfileGray - a special case of ICC_Profiles.
043 *
044 * The ICC_Profile.getInstance() method will return an instance of the 
045 * ICC_ProfileGray subclass when all the following conditions are met:
046 * The device color space of the profile is TYPE_GRAY.
047 * The profile contains a gray TRCTag.
048 * The profile contains a mediaWhitePointTag.
049 *
050 * As per the ICC specification, the color space conversion can then
051 * be done through the following method:
052 * linearGray = grayTRC[deviceGray]
053 *
054 * Note that if the profile contains a CLUT for the color space conversion,
055 * it should be used instead, and the TRC information ignored. 
056 *
057 * @author Sven de Marothy
058 * @since 1.2
059 */
060public class ICC_ProfileGray extends ICC_Profile
061{
062  /**
063   * Compatible with JDK 1.2+.
064   */
065  private static final long serialVersionUID = -1124721290732002649L;
066  private transient float[] whitePoint;
067
068  /**
069   * Package-private constructor used by ICC_ColorSpace for creating an
070   * ICC_ProfileGray from a predefined ColorSpace (CS_GRAY)
071   */
072  ICC_ProfileGray(int cspace)
073  {
074    super(cspace);
075    whitePoint = getXYZData(icSigMediaWhitePointTag);
076  }
077
078  /**
079   * Package-private constructor used by ICC_ColorSpace for creating an
080   * ICC_ProfileGray from profile data.
081   */
082  ICC_ProfileGray(byte[] data)
083  {
084    super(data);
085    whitePoint = getXYZData(icSigMediaWhitePointTag);
086  }
087
088
089  /**
090   * Returns the media white point of the profile.
091   */
092  public float[] getMediaWhitePoint()
093  {
094    float[] wp = new float[3];
095    wp[0] = whitePoint[0];
096    wp[1] = whitePoint[1];
097    wp[2] = whitePoint[2];
098    return wp;
099  }
100
101  /**
102   * Returns the TRC gamma value.
103   * @throws ProfileDataException if the TRC is described by a lookup
104   * table and not a gamma value.
105   */
106  public float getGamma()
107  {
108    short[] data = getCurve(icSigGrayTRCTag);
109    if (data == null)
110      throw new IllegalArgumentException("Couldn't read Gray TRC data.");
111    if (data.length != 1)
112      throw new ProfileDataException("TRC is a table, not a gamma value.");
113
114    // convert the unsigned 7.8 fixed-point gamma to a float.
115    double gamma = (double) (data[0] & (0xFFFF)) / 256.0;
116    return (float) gamma;
117  }
118
119  /**
120   * Returns the TRC lookup table.
121   * @throws ProfileDataException if the TRC is described by a gamma value
122   * and not a lookup table.
123   */
124  public short[] getTRC()
125  {
126    short[] data = getCurve(icSigGrayTRCTag);
127    if (data == null)
128      throw new IllegalArgumentException("Couldn't read Gray TRC data.");
129    if (data.length <= 1)
130      throw new ProfileDataException("Gamma value, not a TRC table.");
131    return data;
132  }
133} // class ICC_ProfileGray