我知道我需要使用循环来查看$palette
数组,但在进行颜色比较时需要帮助。
目标是查找$rgbcolor
与$palette
最接近的值并显示与$palette
匹配的颜色。
<?php
//input color
$rgbcolor = array(110,84,43);
//listed color
$palette = array(
array(238,216,152),
array(252,216,113),
array(253,217,0),
array(255,208,62),
array(255,182,20),
array(206,137,0),
array(235,169,0),
array(170,137,0),
array(173,132,28),
array(183,131,0),
array(139,120,37),
array(108,86,26)
);
?>
有许多不同的方法来确定颜色“距离”。
存在绝对距离,即每个通道值之间的差之和:
function absoluteColorDistance($color_a, $color_b) {
return
abs($color_a[0] - $color_b[0]) +
abs($color_a[1] - $color_b[1]) +
abs($color_a[2] - $color_b[2]);
}
亮度方面也有差异,这将提供更多颜色独立的比较:
function luminanceDistance($color_a, $color_b) {
$luminance_f = function ($red, $green, $blue) {
// source: https://en.wikipedia.org/wiki/Relative_luminance
$luminance = (int) (0.2126*$red + 0.7152*$green + 0.0722*$blue);
return $luminance;
};
return abs(
$luminance_f($color_a[0], $color_a[1], $color_a[2]) -
$luminance_f($color_b[0], $color_b[1], $color_b[2])
);
}
一旦弄清楚如何比较颜色,下一个需要解决的问题就是找到与目标颜色的距离最小的颜色:
$nearest_distance = null;
$nearest_color = null;
foreach ($palate as $test_color) {
$test_distance = luminanceDistance($test_color, $rgbcolor);
if (isset($nearest_distance)) {
if ($nearest_distance > $test_distance) {
// found a closer color
$nearest_distance = $test_distance;
$nearest_color = $test_color;
}
} else {
$nearest_color = $test_color;
$nearest_distance = $test_distance;
}
}