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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/SrgbConverter.java | |
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Diffstat (limited to 'libjava/classpath/gnu/java/awt/color/SrgbConverter.java')
-rw-r--r-- | libjava/classpath/gnu/java/awt/color/SrgbConverter.java | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/libjava/classpath/gnu/java/awt/color/SrgbConverter.java b/libjava/classpath/gnu/java/awt/color/SrgbConverter.java new file mode 100644 index 000000000..76831c0ea --- /dev/null +++ b/libjava/classpath/gnu/java/awt/color/SrgbConverter.java @@ -0,0 +1,152 @@ +/* SrgbConverter.java -- sRGB conversion class + 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; + + +/** + * SrgbConverter - conversion routines for the sRGB colorspace + * sRGB is a standard for RGB colorspaces, adopted by the w3c. + * + * The specification is available at: + * http://www.w3.org/Graphics/Color/sRGB.html + * + * @author Sven de Marothy + */ +/** + * + * Note the matrix numbers used here are NOT identical to those in the + * w3 spec, as those numbers are CIE XYZ relative a D65 white point. + * The CIE XYZ we use is relative a D50 white point, so therefore a + * linear Bradford transform matrix for D65->D50 mapping has been applied. + * (The ICC documents describe this transform) + * + * Linearized Bradford transform: + * 0.8951 0.2664 -0.1614 + * -0.7502 1.7135 0.0367 + * 0.0389 -0.0685 1.0296 + * + * Inverse: + * 0.9870 -0.1471 0.1600 + * 0.4323 0.5184 0.0493 + * -0.00853 0.0400 0.9685 + */ +public class SrgbConverter implements ColorSpaceConverter +{ + public float[] fromCIEXYZ(float[] in) + { + return XYZtoRGB(in); + } + + public float[] toCIEXYZ(float[] in) + { + return RGBtoXYZ(in); + } + + public float[] toRGB(float[] in) + { + float[] out = new float[3]; + System.arraycopy(in, 0, out, 0, 3); + return out; + } + + public float[] fromRGB(float[] in) + { + float[] out = new float[3]; + System.arraycopy(in, 0, out, 0, 3); + return out; + } + + /** + * CIE XYZ (D50 relative) --> sRGB + * + * Static as it's used by other ColorSpaceConverters to + * convert to sRGB if the color space is defined in XYZ. + */ + public static float[] XYZtoRGB(float[] in) + { + float[] temp = new float[3]; + temp[0] = 3.1338f * in[0] - 1.6171f * in[1] - 0.4907f * in[2]; + temp[1] = -0.9785f * in[0] + 1.9160f * in[1] + 0.0334f * in[2]; + temp[2] = 0.0720f * in[0] - 0.2290f * in[1] + 1.4056f * in[2]; + + float[] out = new float[3]; + for (int i = 0; i < 3; i++) + { + if (temp[i] < 0) + temp[i] = 0.0f; + if (temp[i] > 1) + temp[i] = 1.0f; + if (temp[i] <= 0.00304f) + out[i] = temp[i] * 12.92f; + else + out[i] = 1.055f * ((float) Math.exp((1 / 2.4) * Math.log(temp[i]))) + - 0.055f; + } + return out; + } + + /** + * sRGB --> CIE XYZ (D50 relative) + * + * Static as it's used by other ColorSpaceConverters to + * convert to XYZ if the color space is defined in RGB. + */ + public static float[] RGBtoXYZ(float[] in) + { + float[] temp = new float[3]; + float[] out = new float[3]; + for (int i = 0; i < 3; i++) + if (in[i] <= 0.03928f) + temp[i] = in[i] / 12.92f; + else + temp[i] = (float) Math.exp(2.4 * Math.log((in[i] + 0.055) / 1.055)); + + /* + * Note: The numbers which were used to calculate this only had four + * digits of accuracy. So don't be fooled by the number of digits here. + * If someone has more accurate source, feel free to update this. + */ + out[0] = (float) (0.436063750222 * temp[0] + 0.385149601465 * temp[1] + + 0.143086418888 * temp[2]); + out[1] = (float) (0.222450894035 * temp[0] + 0.71692584775 * temp[1] + + 0.060624511256 * temp[2]); + out[2] = (float) (0.0138985186 * temp[0] + 0.097079690112 * temp[1] + + 0.713996045725 * temp[2]); + return out; + } +} |