001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.commons.imaging.formats.tiff.photometricinterpreters; 018 019import java.io.IOException; 020 021import org.apache.commons.imaging.ImagingException; 022import org.apache.commons.imaging.common.ImageBuilder; 023 024/** 025 * Photometric interpretation Logluv support. Logluv is an encoding for storing data inside TIFF images. 026 * 027 * @see <a href="https://en.wikipedia.org/wiki/Logluv_TIFF">Logluv TIFF</a> 028 */ 029public class PhotometricInterpreterLogLuv extends AbstractPhotometricInterpreter { 030 031 /** 032 * Rgb values (reg-green-blue, as R-G-B, as in the RGB color model). 033 */ 034 static class RgbValues { 035 public int r; 036 public int g; 037 public int b; 038 } 039 040 /** 041 * Tristimulus color values (red-green-blue, as X-Y-Z, in the CIE XYZ color space). 042 */ 043 static class TristimulusValues { 044 public float x; 045 public float y; 046 public float z; 047 } 048 049 public PhotometricInterpreterLogLuv(final int samplesPerPixel, final int[] bitsPerSample, final int predictor, final int width, final int height) { 050 super(samplesPerPixel, bitsPerSample, predictor, width, height); 051 } 052 053 /** 054 * Receives a triplet tristimulus values (CIE XYZ) and then does a CIELAB-CIEXYZ conversion (consult Wikipedia link for formula), where the CIELAB values 055 * are used to calculate the tristimulus values of the reference white point. 056 * 057 * @param tristimulusValues the XYZ tristimulus values 058 * @return RGB values 059 * @see <a href="https://en.wikipedia.org/wiki/CIELAB_color_space">CIELAB color space</a> 060 */ 061 RgbValues getRgbValues(final TristimulusValues tristimulusValues) { 062 final float varX = tristimulusValues.x / 100f; // X = From 0 to ref_X 063 final float varY = tristimulusValues.y / 100f; // Y = From 0 to ref_Y 064 final float varZ = tristimulusValues.z / 100f; // Z = From 0 to ref_Y 065 066 float varR = varX * 3.2406f + varY * -1.5372f + varZ * -0.4986f; 067 float varG = varX * -0.9689f + varY * 1.8758f + varZ * 0.0415f; 068 float varB = varX * 0.0557f + varY * -0.2040f + varZ * 1.0570f; 069 070 if (varR > 0.0031308) { 071 varR = 1.055f * (float) Math.pow(varR, 1 / 2.4) - 0.055f; 072 } else { 073 varR = 12.92f * varR; 074 } 075 if (varG > 0.0031308) { 076 varG = 1.055f * (float) Math.pow(varG, 1 / 2.4) - 0.055f; 077 } else { 078 varG = 12.92f * varG; 079 } 080 081 if (varB > 0.0031308) { 082 varB = 1.055f * (float) Math.pow(varB, 1 / 2.4) - 0.055f; 083 } else { 084 varB = 12.92f * varB; 085 } 086 087 // var_R = ((var_R + 0.16561039f) / (3.0152583f + 0.16561039f)); 088 // var_G = ((var_G + 0.06561642f) / (3.0239854f + 0.06561642f)); 089 // var_B = ((var_B + 0.19393992f) / (3.1043448f + 0.19393992f)); 090 091 final RgbValues values = new RgbValues(); 092 values.r = (int) (varR * 255f); 093 values.g = (int) (varG * 255f); 094 values.b = (int) (varB * 255f); 095 return values; 096 } 097 098 /** 099 * Receives a triplet of CIELAB values, and calculates the tristimulus values. The reference white point used here is the equivalent to summer sun and sky. 100 * 101 * @param cieL lightness from black to white 102 * @param cieA lightness from green to red 103 * @param cieB lightness from blue to yellow 104 * @return tristimulus (X, Y, and Z) values 105 * @see <a href="https://en.wikipedia.org/wiki/CIELAB_color_space">CIELAB color space</a> 106 * @see <a href="https://en.wikipedia.org/wiki/White_point">White point</a> 107 */ 108 TristimulusValues getTristimulusValues(final int cieL, final int cieA, final int cieB) { 109 float varY = (cieL * 100.0f / 255.0f + 16.0f) / 116.0f; 110 float varX = cieA / 500.0f + varY; 111 float varZ = varY - cieB / 200.0f; 112 113 final float varXCube = (float) Math.pow(varX, 3.0d); 114 final float varYCube = (float) Math.pow(varY, 3.0d); 115 final float varZCube = (float) Math.pow(varZ, 3.0d); 116 117 if (varYCube > 0.008856f) { 118 varY = varYCube; 119 } else { 120 varY = (varY - 16 / 116.0f) / 7.787f; 121 } 122 123 if (varXCube > 0.008856f) { 124 varX = varXCube; 125 } else { 126 varX = (varX - 16 / 116.0f) / 7.787f; 127 } 128 129 if (varZCube > 0.008856f) { 130 varZ = varZCube; 131 } else { 132 varZ = (varZ - 16 / 116.0f) / 7.787f; 133 } 134 135 // These reference values are the relative white points (XYZ) for commons scene types. 136 // The chosen values here reflect a scene with Summer Sun and Sky, temperature of 6504 K, 137 // X 95.047, Y 100.0, and Z 108.883. 138 // See Color Science by Wyszecki and Stiles for more 139 final float refX = 95.047f; 140 final float refY = 100.000f; 141 final float refZ = 108.883f; 142 143 final TristimulusValues values = new TristimulusValues(); 144 values.x = refX * varX; // ref_X = 95.047 Observer= 2°, Illuminant= D65 145 values.y = refY * varY; // ref_Y = 100.000 146 values.z = refZ * varZ; // ref_Z = 108.883 147 return values; 148 } 149 150 @Override 151 public void interpretPixel(final ImageBuilder imageBuilder, final int[] samples, final int x, final int y) throws ImagingException, IOException { 152 if (samples == null || samples.length != 3) { 153 throw new ImagingException("Invalid length of bits per sample (expected 3)."); 154 } 155 156 // CIE illuminants. An illuminant is a theorical source of visible light with a profile. 157 // CIE stands for Commission Internationale de l'Eclairage, or International 158 // Comission on Illumination. 159 final int cieL = samples[0]; 160 final int cieA = (byte) samples[1]; 161 final int cieB = (byte) samples[2]; 162 163 final TristimulusValues tristimulusValues = getTristimulusValues(cieL, cieA, cieB); 164 165 // ref_X = 95.047 //Observer = 2°, Illuminant = D65 166 // ref_Y = 100.000 167 // ref_Z = 108.883 168 169 final RgbValues rgbValues = getRgbValues(tristimulusValues); 170 171 // float R = 1.910f * X - 0.532f * Y - 0.288f * Z; 172 // float G = -0.985f * X + 1.999f * Y - 0.028f * Z; 173 // float B = 0.058f * X - 0.118f * Y + 0.898f * Z; 174 175 final int red = Math.min(255, Math.max(0, rgbValues.r)); 176 final int green = Math.min(255, Math.max(0, rgbValues.g)); 177 final int blue = Math.min(255, Math.max(0, rgbValues.b)); 178 final int alpha = 0xff; 179 final int rgb = alpha << 24 | red << 16 | green << 8 | blue << 0; 180 imageBuilder.setRgb(x, y, rgb); 181 182 } 183}