我本想对@MichaelChirico的回答发表评论，但我没有足够的声誉。这里有一个在R中返回颜色的例子:

get_text_colour <- function(
    background_colour,
    light_text_colour = 'white',
    dark_text_colour = 'black',
    threshold = 0.5
) {

    background_luminance <- c( 
        c( .299, .587, .114 ) %*% col2rgb( background_colour ) / 255
    )

    return(
        ifelse(
            background_luminance < threshold,
            light_text_colour,
            dark_text_colour
        )
    )
}

> get_text_colour( background_colour = 'blue' )
[1] "white"

> get_text_colour( background_colour = c( 'blue', 'yellow', 'pink' ) )
[1] "white" "black" "black"

> get_text_colour( background_colour = c('black', 'white', '#236FAB', 'darkred', '#01F11F') )
[1] "white" "black" "white" "white" "black"

我有同样的问题，但我必须在PHP开发它。我用了@Garek的解决方案，我也用了这个答案: 转换十六进制颜色到RGB值在PHP转换十六进制颜色代码到RGB。

所以我要分享它。

我想在给定的背景颜色下使用这个函数，但不总是从“#”开始。

//So it can be used like this way:
$color = calculateColor('#804040');
echo $color;

//or even this way:
$color = calculateColor('D79C44');
echo '<br/>'.$color;

function calculateColor($bgColor){
    //ensure that the color code will not have # in the beginning
    $bgColor = str_replace('#','',$bgColor);
    //now just add it
    $hex = '#'.$bgColor;
    list($r, $g, $b) = sscanf($hex, "#%02x%02x%02x");
    $color = 1 - ( 0.299 * $r + 0.587 * $g + 0.114 * $b)/255;

    if ($color < 0.5)
        $color = '#000000'; // bright colors - black font
    else
        $color = '#ffffff'; // dark colors - white font

    return $color;
}

丑陋的Python，如果你不想写它:)

'''
Input a string without hash sign of RGB hex digits to compute
complementary contrasting color such as for fonts
'''
def contrasting_text_color(hex_str):
    (r, g, b) = (hex_str[:2], hex_str[2:4], hex_str[4:])
    return '000' if 1 - (int(r, 16) * 0.299 + int(g, 16) * 0.587 + int(b, 16) * 0.114) / 255 < 0.5 else 'fff'

Swift 4示例:

extension UIColor {

    var isLight: Bool {
        let components = cgColor.components

        let firstComponent = ((components?[0]) ?? 0) * 299
        let secondComponent = ((components?[1]) ?? 0) * 587
        let thirdComponent = ((components?[2]) ?? 0) * 114
        let brightness = (firstComponent + secondComponent + thirdComponent) / 1000

        return !(brightness < 0.6)
    }

}

更新-发现0.6是一个更好的查询测试平台

objective-c的实现

+ (UIColor*) getContrastColor:(UIColor*) color {
    CGFloat red, green, blue, alpha;
    [color getRed:&red green:&green blue:&blue alpha:&alpha];
    double a = ( 0.299 * red + 0.587 * green + 0.114 * blue);
    return (a > 0.5) ? [[UIColor alloc]initWithRed:0 green:0 blue:0 alpha:1] : [[UIColor alloc]initWithRed:255 green:255 blue:255 alpha:1];
}

谢谢你写这篇文章。

对于可能感兴趣的人，这里有一个Delphi中的函数示例:

function GetContrastColor(ABGColor: TColor): TColor;
var
  ADouble: Double;
  R, G, B: Byte;
begin
  if ABGColor <= 0 then
  begin
    Result := clWhite;
    Exit; // *** EXIT RIGHT HERE ***
  end;

  if ABGColor = clWhite then
  begin
    Result := clBlack;
    Exit; // *** EXIT RIGHT HERE ***
  end;

  // Get RGB from Color
  R := GetRValue(ABGColor);
  G := GetGValue(ABGColor);
  B := GetBValue(ABGColor);

  // Counting the perceptive luminance - human eye favors green color...
  ADouble := 1 - (0.299 * R + 0.587 * G + 0.114 * B) / 255;

  if (ADouble < 0.5) then
    Result := clBlack  // bright colors - black font
  else
    Result := clWhite;  // dark colors - white font
end;