Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;
/*
 * Copyright 2015 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

public class Main {
    private static final double XYZ_WHITE_REFERENCE_X = 95.047;
    private static final double XYZ_WHITE_REFERENCE_Y = 100;
    private static final double XYZ_WHITE_REFERENCE_Z = 108.883;
    private static final double XYZ_EPSILON = 0.008856;
    private static final double XYZ_KAPPA = 903.3;

    /**
     * Convert RGB components to its CIE Lab representative components.
     *
     * <ul>
     * <li>outLab[0] is L [0 ...1)</li>
     * <li>outLab[1] is a [-128...127)</li>
     * <li>outLab[2] is b [-128...127)</li>
     * </ul>
     *
     * @param r      red component value [0..255]
     * @param g      green component value [0..255]
     * @param b      blue component value [0..255]
     * @param outLab 3-element array which holds the resulting LAB components
     */
    public static void RGBToLAB(int r, int g, int b, double[] outLab) {
        // First we convert RGB to XYZ
        RGBToXYZ(r, g, b, outLab);
        // outLab now contains XYZ
        XYZToLAB(outLab[0], outLab[1], outLab[2], outLab);
        // outLab now contains LAB representation
    }

    public static void RGBToXYZ(int r, int g, int b, double[] outXyz) {
        if (outXyz.length != 3) {
            throw new IllegalArgumentException("outXyz must have a length of 3.");
        }

        double sr = r / 255.0;
        sr = sr < 0.04045 ? sr / 12.92 : Math.pow((sr + 0.055) / 1.055, 2.4);
        double sg = g / 255.0;
        sg = sg < 0.04045 ? sg / 12.92 : Math.pow((sg + 0.055) / 1.055, 2.4);
        double sb = b / 255.0;
        sb = sb < 0.04045 ? sb / 12.92 : Math.pow((sb + 0.055) / 1.055, 2.4);

        outXyz[0] = 100 * (sr * 0.4124 + sg * 0.3576 + sb * 0.1805);
        outXyz[1] = 100 * (sr * 0.2126 + sg * 0.7152 + sb * 0.0722);
        outXyz[2] = 100 * (sr * 0.0193 + sg * 0.1192 + sb * 0.9505);
    }

    public static void XYZToLAB(double x, double y, double z, double[] outLab) {
        if (outLab.length != 3) {
            throw new IllegalArgumentException("outLab must have a length of 3.");
        }
        x = pivotXyzComponent(x / XYZ_WHITE_REFERENCE_X);
        y = pivotXyzComponent(y / XYZ_WHITE_REFERENCE_Y);
        z = pivotXyzComponent(z / XYZ_WHITE_REFERENCE_Z);
        outLab[0] = Math.max(0, 116 * y - 16);
        outLab[1] = 500 * (x - y);
        outLab[2] = 200 * (y - z);
    }

    private static double pivotXyzComponent(double component) {
        return component > XYZ_EPSILON ? Math.pow(component, 1 / 3.0) : (XYZ_KAPPA * component + 16) / 116;
    }
}