Returns the luminance of a color. - Android Graphics

Android examples for Graphics:Color

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Description

Returns the luminance of a color.

Demo Code

/*//from w  ww .jav  a2s . c  o  m
 * Copyright 2014 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.
 */
//package com.java2s;
import android.graphics.Color;

public class Main {
    /**
     * Returns the luminance of a color.
     *
     * Formula defined here: http://www.w3.org/TR/2008/REC-WCAG20-20081211/#relativeluminancedef
     */
    private static double calculateLuminance(int color) {
        double red = Color.red(color) / 255d;
        red = red < 0.03928 ? red / 12.92 : Math.pow((red + 0.055) / 1.055,
                2.4);

        double green = Color.green(color) / 255d;
        green = green < 0.03928 ? green / 12.92 : Math.pow(
                (green + 0.055) / 1.055, 2.4);

        double blue = Color.blue(color) / 255d;
        blue = blue < 0.03928 ? blue / 12.92 : Math.pow(
                (blue + 0.055) / 1.055, 2.4);

        return (0.2126 * red) + (0.7152 * green) + (0.0722 * blue);
    }
}

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