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author | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
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committer | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
commit | 554fd8c5195424bdbcabf5de30fdc183aba391bd (patch) | |
tree | 976dc5ab7fddf506dadce60ae936f43f58787092 /libjava/classpath/gnu/java/awt/color/ToneReproductionCurve.java | |
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Diffstat (limited to 'libjava/classpath/gnu/java/awt/color/ToneReproductionCurve.java')
-rw-r--r-- | libjava/classpath/gnu/java/awt/color/ToneReproductionCurve.java | 177 |
1 files changed, 177 insertions, 0 deletions
diff --git a/libjava/classpath/gnu/java/awt/color/ToneReproductionCurve.java b/libjava/classpath/gnu/java/awt/color/ToneReproductionCurve.java new file mode 100644 index 000000000..208e16883 --- /dev/null +++ b/libjava/classpath/gnu/java/awt/color/ToneReproductionCurve.java @@ -0,0 +1,177 @@ +/* ToneReproductionCurve.java -- Representation of an ICC 'curv' type TRC + Copyright (C) 2004 Free Software Foundation + +This file is part of GNU Classpath. + +GNU Classpath is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2, or (at your option) +any later version. + +GNU Classpath is distributed in the hope that it will be useful, but +WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +General Public License for more details. + +You should have received a copy of the GNU General Public License +along with GNU Classpath; see the file COPYING. If not, write to the +Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301 USA. + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + +package gnu.java.awt.color; + + +/** + * ToneReproductionCurve - TRCs are used to describe RGB + * and Grayscale profiles. The TRC is essentially the gamma + * function of the color space. + * + * For example, Apple RGB has a gamma of 1.8, most monitors are ~2.2, + * sRGB is 2.4 with a small linear part near 0. + * Linear spaces are of course 1.0. + * (The exact function is implemented in SrgbConverter) + * + * The ICC specification allows the TRC to be described as a single + * Gamma value, where the function is thus out = in**gamma. + * Alternatively, the gamma function may be represented by a lookup table + * of values, in which case linear interpolation is used. + * + * @author Sven de Marothy + */ +public class ToneReproductionCurve +{ + private float[] trc; + private float gamma; + private float[] reverseTrc; + + /** + * Constructs a TRC from a gamma values + */ + public ToneReproductionCurve(float gamma) + { + trc = null; + reverseTrc = null; + this.gamma = gamma; + } + + /** + * Constructs a TRC from a set of float values + */ + public ToneReproductionCurve(float[] trcValues) + { + trc = new float[trcValues.length]; + System.arraycopy(trcValues, 0, trc, 0, trcValues.length); + setupReverseTrc(); + } + + /** + * Constructs a TRC from a set of short values normalized to + * the 0-65535 range (as in the ICC profile file). + * (Note the values are treated as unsigned) + */ + public ToneReproductionCurve(short[] trcValues) + { + trc = new float[trcValues.length]; + for (int i = 0; i < trcValues.length; i++) + trc[i] = (float) ((int) trcValues[i] & (0xFFFF)) / 65535.0f; + setupReverseTrc(); + } + + /** + * Performs a TRC lookup + */ + public float lookup(float in) + { + float out; + + if (trc == null) + { + if (in == 0f) + return 0.0f; + return (float) Math.exp(gamma * Math.log(in)); + } + else + { + double alpha = in * (trc.length - 1); + int index = (int) Math.floor(alpha); + alpha = alpha - (double) index; + if (index >= trc.length - 1) + return trc[trc.length - 1]; + if (index <= 0) + return trc[0]; + out = (float) (trc[index] * (1.0 - alpha) + trc[index + 1] * alpha); + } + return out; + } + + /** + * Performs an reverse lookup + */ + public float reverseLookup(float in) + { + float out; + + if (trc == null) + { + if (in == 0f) + return 0.0f; + return (float) Math.exp((1.0 / gamma) * Math.log(in)); + } + else + { + double alpha = in * (reverseTrc.length - 1); + int index = (int) Math.floor(alpha); + alpha = alpha - (double) index; + if (index >= reverseTrc.length - 1) + return reverseTrc[reverseTrc.length - 1]; + if (index <= 0) + return reverseTrc[0]; + out = (float) (reverseTrc[index] * (1.0 - alpha) + + reverseTrc[index + 1] * alpha); + } + return out; + } + + /** + * Calculates a reverse-lookup table. + * We use a whopping 10,000 entries.. This is should be more than any + * real-life TRC table (typically around 256-1024) so we won't be losing + * any precision. + * + * This will of course generate completely invalid results if the curve + * is not monotonic and invertable. But what's the alternative? + */ + public void setupReverseTrc() + { + reverseTrc = new float[10000]; + int j = 0; + for (int i = 0; i < 10000; i++) + { + float n = ((float) i) / 10000f; + while (trc[j + 1] < n && j < trc.length - 2) + j++; + + if (j == trc.length - 2) + reverseTrc[i] = trc[trc.length - 1]; + else + reverseTrc[i] = (j + (n - trc[j]) / (trc[j + 1] - trc[j])) / ((float) trc.length); + } + } +} |