根据来自链接的不同输入，使前景颜色黑色或白色取决于背景和这个线程，我为颜色做了一个扩展类，为您提供所需的对比色。

代码如下:

 public static class ColorExtension
{       
    public static int PerceivedBrightness(this Color c)
    {
        return (int)Math.Sqrt(
        c.R * c.R * .299 +
        c.G * c.G * .587 +
        c.B * c.B * .114);
    }
    public static Color ContrastColor(this Color iColor, Color darkColor,Color lightColor)
    {
        //  Counting the perceptive luminance (aka luma) - human eye favors green color... 
        double luma = (iColor.PerceivedBrightness() / 255);

        // Return black for bright colors, white for dark colors
        return luma > 0.5 ? darkColor : lightColor;
    }
    public static Color ContrastColor(this Color iColor) => iColor.ContrastColor(Color.Black);
    public static Color ContrastColor(this Color iColor, Color darkColor) => iColor.ContrastColor(darkColor, Color.White);
    // Converts a given Color to gray
    public static Color ToGray(this Color input)
    {
        int g = (int)(input.R * .299) + (int)(input.G * .587) + (int)(input.B * .114);
        return Color.FromArgb(input.A, g, g, g);
    }
}

根据@MarkRansom的答案，我创建了一个PHP脚本，你可以在这里找到:

function calcC($c) {
    if ($c <= 0.03928) {
        return $c / 12.92;
    }
    else {
        return pow(($c + 0.055) / 1.055, 2.4);
    }
}

function cutHex($h) {
    return ($h[0] == "#") ? substr($h, 1, 7) : $h;
}

function hexToR($h) {
    return hexdec(substr(cutHex($h), 0, 2));
}

function hexToG($h) {
    return hexdec(substr(cutHex($h), 2, 2)); // Edited
}

function hexToB($h) {
    return hexdec(substr(cutHex($h), 4, 2)); // Edited
}

function computeTextColor($color) {
    $r = hexToR($color);
    $g = hexToG($color);
    $b = hexToB($color);
    $uicolors = [$r / 255, $g / 255, $b / 255];


    $c = array_map("calcC", $uicolors);

    $l = 0.2126 * $c[0] + 0.7152 * $c[1] + 0.0722 * $c[2];
    return ($l > 0.179) ? '#000000' : '#ffffff';
}

我不认为这段代码是我的功劳，因为它不是我的，但我把它留在这里，让其他人将来很快就能找到:

根据Mark Ransoms的回答，下面是一个简单版本的代码片段:

function pickTextColorBasedOnBgColorSimple(bgColor, lightColor, darkColor) {
  var color = (bgColor.charAt(0) === '#') ? bgColor.substring(1, 7) : bgColor;
  var r = parseInt(color.substring(0, 2), 16); // hexToR
  var g = parseInt(color.substring(2, 4), 16); // hexToG
  var b = parseInt(color.substring(4, 6), 16); // hexToB
  return (((r * 0.299) + (g * 0.587) + (b * 0.114)) > 186) ?
    darkColor : lightColor;
}

下面是高级版本的代码片段:

function pickTextColorBasedOnBgColorAdvanced(bgColor, lightColor, darkColor) {
  var color = (bgColor.charAt(0) === '#') ? bgColor.substring(1, 7) : bgColor;
  var r = parseInt(color.substring(0, 2), 16); // hexToR
  var g = parseInt(color.substring(2, 4), 16); // hexToG
  var b = parseInt(color.substring(4, 6), 16); // hexToB
  var uicolors = [r / 255, g / 255, b / 255];
  var c = uicolors.map((col) => {
    if (col <= 0.03928) {
      return col / 12.92;
    }
    return Math.pow((col + 0.055) / 1.055, 2.4);
  });
  var L = (0.2126 * c[0]) + (0.7152 * c[1]) + (0.0722 * c[2]);
  return (L > 0.179) ? darkColor : lightColor;
}

要使用它们，只需调用:

var color = '#EEACAE' // this can be any color
pickTextColorBasedOnBgColorSimple(color, '#FFFFFF', '#000000');

同时，感谢Alx和chetstone。

下面是我基于Mark的惊人回答编写的Java Swing代码:

public static Color getColorBasedOnBackground(Color background, Color darkColor, Color lightColor) {
    // Calculate foreground color based on background (based on https://stackoverflow.com/a/3943023/)
    Color color;
    double[] cL = new double[3];
    double[] colorRGB = new double[] {background.getRed(), background.getGreen(), background.getBlue()};

    for (int i = 0; i < colorRGB.length; i++)
        cL[i] = (colorRGB[i] / 255.0 <= 0.03928) ? colorRGB[i] / 255.0 / 12.92 :
                Math.pow(((colorRGB[i] / 255.0 + 0.055) / 1.055), 2.4);

    double L = 0.2126 * cL[0] + 0.7152 * cL[1] + 0.0722 * cL[2];
    color = (L > Math.sqrt(1.05 * 0.05) - 0.05) ? darkColor : lightColor;

    return color;
}

我正在使用tinyColor库，它也可以做这项工作。

import { TinyColor } from '@ctrl/tinycolor'

// ...

getColorContrast(color = '#66FFFF'): string {
  if(new TinyColor(color).getLuminance() > 0.179) { // 0.179 -> Mark Ransom answer
     return '#000'
  } else {
     return '#fff'
  }
}

此方法也接受rgb颜色，如rgb(102,255,255)

从hex到black或white:

function hexToRgb(hex) {
  var result = /^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(hex);
  return result
    ? [
        parseInt(result[1], 16),
        parseInt(result[2], 16),
        parseInt(result[3], 16)
      ]
    : [0, 0, 0];
}

function lum(hex) {
  var rgb = hexToRgb(hex)
  var lrgb = [];
  rgb.forEach(function(c) {
    c = c / 255.0;
    if (c <= 0.03928) {
      c = c / 12.92;
    } else {
      c = Math.pow((c + 0.055) / 1.055, 2.4);
    }
    lrgb.push(c);
  });
  var lum = 0.2126 * lrgb[0] + 0.7152 * lrgb[1] + 0.0722 * lrgb[2];
  return lum > 0.179 ? "#000000" : "#ffffff";
}