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.ImageReadException; 022import org.apache.commons.imaging.common.ImageBuilder; 023 024/** 025 * Photometric interpretation Logluv support. Logluv is an encoding for storing 026 * data inside TIFF images. 027 * 028 * @see <a href="https://en.wikipedia.org/wiki/Logluv_TIFF">Logluv TIFF</a> 029 */ 030public class PhotometricInterpreterLogLuv extends PhotometricInterpreter { 031 032 /** 033 * Tristimulus color values (red-green-blue, as X-Y-Z, in the CIE XYZ color space). 034 */ 035 static class TristimulusValues { 036 public float x; 037 public float y; 038 public float z; 039 } 040 041 /** 042 * Rgb values (reg-green-blue, as R-G-B, as in the RGB color model). 043 */ 044 static class RgbValues { 045 public int r; 046 public int g; 047 public int b; 048 } 049 050 public PhotometricInterpreterLogLuv(final int samplesPerPixel, 051 final int[] bitsPerSample, final int predictor, final int width, final int height) { 052 super(samplesPerPixel, bitsPerSample, predictor, width, height); 053 } 054 055 @Override 056 public void interpretPixel(final ImageBuilder imageBuilder, final int[] samples, final int x, 057 final int y) throws ImageReadException, IOException { 058 if (samples == null || samples.length != 3) { 059 throw new ImageReadException("Invalid length of bits per sample (expected 3)."); 060 } 061 062 // CIE illuminants. An illuminant is a theorical source of visible light with a profile. 063 // CIE stands for Commission Internationale de l'Eclairage, or International 064 // Comission on Illumination. 065 final int cieL = samples[0]; 066 final int cieA = (byte) samples[1]; 067 final int cieB = (byte) samples[2]; 068 069 final TristimulusValues tristimulusValues = getTristimulusValues(cieL, cieA, cieB); 070 071 // ref_X = 95.047 //Observer = 2°, Illuminant = D65 072 // ref_Y = 100.000 073 // ref_Z = 108.883 074 075 final RgbValues rgbValues = getRgbValues(tristimulusValues); 076 077 // float R = 1.910f * X - 0.532f * Y - 0.288f * Z; 078 // float G = -0.985f * X + 1.999f * Y - 0.028f * Z; 079 // float B = 0.058f * X - 0.118f * Y + 0.898f * Z; 080 081 final int red = Math.min(255, Math.max(0, rgbValues.r)); 082 final int green = Math.min(255, Math.max(0, rgbValues.g)); 083 final int blue = Math.min(255, Math.max(0, rgbValues.b)); 084 final int alpha = 0xff; 085 final int rgb = (alpha << 24) | (red << 16) | (green << 8) | (blue << 0); 086 imageBuilder.setRGB(x, y, rgb); 087 088 } 089 090 /** 091 * Receives a triplet of CIELAB values, and calculates the tristimulus values. 092 * The reference white point used here is the equivalent to summer sun and sky. 093 * 094 * @param cieL lightness from black to white 095 * @param cieA lightness from green to red 096 * @param cieB lightness from blue to yellow 097 * @return tristimulus (X, Y, and Z) values 098 * @see <a href="https://en.wikipedia.org/wiki/CIELAB_color_space">CIELAB color space</a> 099 * @see <a href="https://en.wikipedia.org/wiki/White_point">White point</a> 100 */ 101 TristimulusValues getTristimulusValues(final int cieL, final int cieA, final int cieB) { 102 float var_Y = ((cieL * 100.0f / 255.0f) + 16.0f) / 116.0f; 103 float var_X = cieA / 500.0f + var_Y; 104 float var_Z = var_Y - cieB / 200.0f; 105 106 final float var_x_cube = (float) Math.pow(var_X, 3.0d); 107 final float var_y_cube = (float) Math.pow(var_Y, 3.0d); 108 final float var_z_cube = (float) Math.pow(var_Z, 3.0d); 109 110 if (var_y_cube > 0.008856f) { 111 var_Y = var_y_cube; 112 } else { 113 var_Y = (var_Y - 16 / 116.0f) / 7.787f; 114 } 115 116 if (var_x_cube > 0.008856f) { 117 var_X = var_x_cube; 118 } else { 119 var_X = (var_X - 16 / 116.0f) / 7.787f; 120 } 121 122 if (var_z_cube > 0.008856f) { 123 var_Z = var_z_cube; 124 } else { 125 var_Z = (var_Z - 16 / 116.0f) / 7.787f; 126 } 127 128 // These reference values are the relative white points (XYZ) for commons scene types. 129 // The chosen values here reflect a scene with Summer Sun and Sky, temperature of 6504 K, 130 // X 95.047, Y 100.0, and Z 108.883. 131 // See Color Science by Wyszecki and Stiles for more 132 final float ref_X = 95.047f; 133 final float ref_Y = 100.000f; 134 final float ref_Z = 108.883f; 135 136 final TristimulusValues values = new TristimulusValues(); 137 values.x = ref_X * var_X; // ref_X = 95.047 Observer= 2°, Illuminant= D65 138 values.y = ref_Y * var_Y; // ref_Y = 100.000 139 values.z = ref_Z * var_Z; // ref_Z = 108.883 140 return values; 141 } 142 143 /** 144 * Receives a triplet tristimulus values (CIE XYZ) and then does a CIELAB-CIEXYZ 145 * conversion (consult Wikipedia link for formula), where the CIELAB values are 146 * used to calculate the tristimulus values of the reference white point. 147 * 148 * @param tristimulusValues the XYZ tristimulus values 149 * @return RGB values 150 * @see <a href="https://en.wikipedia.org/wiki/CIELAB_color_space">CIELAB color space</a> 151 */ 152 RgbValues getRgbValues(final TristimulusValues tristimulusValues) { 153 final float var_X = tristimulusValues.x / 100f; // X = From 0 to ref_X 154 final float var_Y = tristimulusValues.y / 100f; // Y = From 0 to ref_Y 155 final float var_Z = tristimulusValues.z / 100f; // Z = From 0 to ref_Y 156 157 float var_R = var_X * 3.2406f + var_Y * -1.5372f + var_Z * -0.4986f; 158 float var_G = var_X * -0.9689f + var_Y * 1.8758f + var_Z * 0.0415f; 159 float var_B = var_X * 0.0557f + var_Y * -0.2040f + var_Z * 1.0570f; 160 161 if (var_R > 0.0031308) { 162 var_R = 1.055f * (float) Math.pow(var_R, (1 / 2.4)) - 0.055f; 163 } else { 164 var_R = 12.92f * var_R; 165 } 166 if (var_G > 0.0031308) { 167 var_G = 1.055f * (float) Math.pow(var_G, (1 / 2.4)) - 0.055f; 168 } else { 169 var_G = 12.92f * var_G; 170 } 171 172 if (var_B > 0.0031308) { 173 var_B = 1.055f * (float) Math.pow(var_B, (1 / 2.4)) - 0.055f; 174 } else { 175 var_B = 12.92f * var_B; 176 } 177 178 // var_R = ((var_R + 0.16561039f) / (3.0152583f + 0.16561039f)); 179 // var_G = ((var_G + 0.06561642f) / (3.0239854f + 0.06561642f)); 180 // var_B = ((var_B + 0.19393992f) / (3.1043448f + 0.19393992f)); 181 182 final RgbValues values = new RgbValues(); 183 values.r = (int) (var_R * 255f); 184 values.g = (int) (var_G * 255f); 185 values.b = (int) (var_B * 255f); 186 return values; 187 } 188}