计算色差

Question

是否可以根据定义的“中心值”检查特定的十六进制颜色是否更接近FFF或000？

我想根据#888检查颜色是否更接近#FFF或#000。所以如果我检查#EFEFEF，它应该返回#FFF，如果我尝试#878787，它应该返回#000。

如何才能做到这一点？我不确定要在谷歌上搜索什么.

提前感谢

Answer 1

解决问题的最简单方法是使用颜色的灰度值计算颜色之间的距离(还有其他方法，但这很简单)。所以就像这样：

// returns a distance between two colors by comparing each component
// using average of the RGB components, eg. a grayscale value
function color_distance($a, $b)
{
    $decA = hexdec(substr($a, 1));
    $decB = hexdec(substr($a, 1));
    $avgA = (($decA & 0xFF) + (($decA >> 8) & 0xFF) + (($decA >> 16) & 0xFF)) / 3;
    $avgB = (($decB & 0xFF) + (($decB >> 8) & 0xFF) + (($decB >> 16) & 0xFF)) / 3;
    return abs($avgA - $avgB);
}

// I am going to leave the naming of the function to you ;)
// How this works is that it'll return $minColor if $color is closer to $refColorMin
// and $maxColor if $color is closer to $refColorMax
// all colors should be passed in format #RRGGBB
function foo($color, $refColorMin, $refColorMax, $minColor, $maxColor)
{
    $distMin = color_distance($color, $refColorMin);
    $distMax = color_distance($color, $refColorMax);
    return ($distMin < $distMax) ? $minColor : $maxColor;
}

// Example usage to answer your original question:
$colorA = foo('#EFEFEF', '#888888', '#FFFFFF', '#000000', '#FFFFFF');
$colorA = foo('#898989', '#888888', '#FFFFFF', '#000000', '#FFFFFF');
// Check the values
var_dump($colorA, $colorB);

输出为：

string(7) "#FFFFFF"
string(7) "#000000"

Answer 2

您可以将颜色转换为数字：

$color_num = hexdec(substr($color, 1)); // skip the initial #

然后将它们与0x0或0xffffff进行比较。

您还可以将它们分解为R、G和B，并进行三次比较；然后对它们进行平均？不确定你想要这个东西有多精确:)

Answer 3

您可以执行类似以下操作：

function hex2rgb($hex) {
   $hex = str_replace("#", "", $hex);

   if(strlen($hex) == 3) {
      $r = hexdec(substr($hex,0,1).substr($hex,0,1));
      $g = hexdec(substr($hex,1,1).substr($hex,1,1));
      $b = hexdec(substr($hex,2,1).substr($hex,2,1));
   } else {
      $r = hexdec(substr($hex,0,2));
      $g = hexdec(substr($hex,2,2));
      $b = hexdec(substr($hex,4,2));
   }
   $rgb = array($r, $g, $b);
   //return implode(",", $rgb); // returns the rgb values separated by commas
   return $rgb; // returns an array with the rgb values
}

$rgb = hex2rgb("#cc0");

由此，您可以获取$rgb的值，并查看它们的值是否平均大于或小于122.5。如果它大于122.5，你将更接近#FFFFFF，低于122.5，你将更接近#000000。