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.
 */

import android.graphics.Color;

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;
    private static final ThreadLocal<double[]> TEMP_ARRAY = new ThreadLocal<>();

    /**
     * Converts a color from CIE Lab to its RGB representation.
     *
     * @param l L component value [0...100]
     * @param a A component value [-128...127]
     * @param b B component value [-128...127]
     * @return int containing the RGB representation
     */
    public static int LABToColor(final double l, final double a, final double b) {
        final double[] result = getTempDouble3Array();
        LABToXYZ(l, a, b, result);
        return XYZToColor(result[0], result[1], result[2]);
    }

    private static double[] getTempDouble3Array() {
        double[] result = TEMP_ARRAY.get();
        if (result == null) {
            result = new double[3];
            TEMP_ARRAY.set(result);
        }
        return result;
    }

    public static void LABToXYZ(final double l, final double a, final double b, double[] outXyz) {
        final double fy = (l + 16) / 116;
        final double fx = a / 500 + fy;
        final double fz = fy - b / 200;

        double tmp = Math.pow(fx, 3);
        final double xr = tmp > XYZ_EPSILON ? tmp : (116 * fx - 16) / XYZ_KAPPA;
        final double yr = l > XYZ_KAPPA * XYZ_EPSILON ? Math.pow(fy, 3) : l / XYZ_KAPPA;

        tmp = Math.pow(fz, 3);
        final double zr = tmp > XYZ_EPSILON ? tmp : (116 * fz - 16) / XYZ_KAPPA;

        outXyz[0] = xr * XYZ_WHITE_REFERENCE_X;
        outXyz[1] = yr * XYZ_WHITE_REFERENCE_Y;
        outXyz[2] = zr * XYZ_WHITE_REFERENCE_Z;
    }

    public static int XYZToColor(double x, double y, double z) {
        double r = (x * 3.2406 + y * -1.5372 + z * -0.4986) / 100;
        double g = (x * -0.9689 + y * 1.8758 + z * 0.0415) / 100;
        double b = (x * 0.0557 + y * -0.2040 + z * 1.0570) / 100;

        r = r > 0.0031308 ? 1.055 * Math.pow(r, 1 / 2.4) - 0.055 : 12.92 * r;
        g = g > 0.0031308 ? 1.055 * Math.pow(g, 1 / 2.4) - 0.055 : 12.92 * g;
        b = b > 0.0031308 ? 1.055 * Math.pow(b, 1 / 2.4) - 0.055 : 12.92 * b;

        return Color.rgb(constrain((int) Math.round(r * 255), 0, 255), constrain((int) Math.round(g * 255), 0, 255),
                constrain((int) Math.round(b * 255), 0, 255));
    }

    private static float constrain(float amount, float low, float high) {
        return amount < low ? low : (amount > high ? high : amount);
    }

    private static int constrain(int amount, int low, int high) {
        return amount < low ? low : (amount > high ? high : amount);
    }
}