imagecolorclosesthwb

(PHP 4 >= 4.0.1, PHP 5, PHP 7)

imagecolorclosesthwb — 取得与给定颜色最接近的色度的黑白色的索引

说明

int imagecolorclosesthwb ( resource $image , int $red , int $green , int $blue )

取得与给定颜色最接近的色度的黑白色的索引。

参数

image: 由图象创建函数(例如 imagecreatetruecolor() )返回的图象资源。
red: 红色成分的值。
green: 绿色成分的值。
blue: 蓝色成分的值。

返回值

返回一个整数，是给定颜色最接近的色度的黑白色的索引。

范例

Example #1 使用 imagecolorclosesthwb() 的例子

  <?php
$im  =  imagecreatefromgif ( 'php.gif' );

echo  'HWB: '  .  imagecolorclosesthwb ( $im ,  116 ,  115 ,  152 );

 imagedestroy ( $im );
 ?>

以上例程的输出类似于：

HWB: 33

更新日志

版本	说明
5.3.0	在 Windows 平台上可用

参见

imagecolorclosest() - 取得与指定的颜色最接近的颜色的索引值

用户评论:

[#1] Xong [2009-06-22 03:56:21]

I have written a function which uses the deltaE-function of the CMC.
It returns much better results than imagecolorclosestHWB() or imageColorClosest().

A test-script is online on http://www.fuhrpark-software.de/spielwiese/color.php?color=ffff00

<?php function getNearestColor( $givenColor, $palette = array( 'blue' => '43aafd','red' => 'fe6256','green' => '64b949','yellow' => 'fcf357', 'black' => '656565','white' => 'fdfdfd','orange' => 'fea800','purple' => '9773fe') ) { if(!function_exists('rgb2lab')) { function rgb2lab($rgb) { $eps = 216/24389; $k = 24389/27; // reference white D50 $xr = 0.964221; $yr = 1.0; $zr = 0.825211; $rgb[0] = $rgb[0]/255; //R 0..1 $rgb[1] = $rgb[1]/255; //G 0..1 $rgb[2] = $rgb[2]/255; //B 0..1 // assuming sRGB (D65) $rgb[0] = ($rgb[0] <= 0.04045)?($rgb[0]/12.92):pow(($rgb[0]+0.055)/1.055,2.4); $rgb[1] = ($rgb[1] <= 0.04045)?($rgb[1]/12.92):pow(($rgb[1]+0.055)/1.055,2.4); $rgb[2] = ($rgb[2] <= 0.04045)?($rgb[2]/12.92):pow(($rgb[2]+0.055)/1.055,2.4); // sRGB D50 $x = 0.4360747*$rgb[0] + 0.3850649*$rgb[1] + 0.1430804 *$rgb[2]; $y = 0.2225045*$rgb[0] + 0.7168786*$rgb[1] + 0.0606169 *$rgb[2]; $z = 0.0139322*$rgb[0] + 0.0971045*$rgb[1] + 0.7141733 *$rgb[2]; $xr = $x/$xr; $yr = $y/$yr; $zr = $z/$zr; $fx = ($xr > $eps)?pow($xr, 1/3):($fx = ($k * $xr + 16) / 116); $fy = ($yr > $eps)?pow($yr, 1/3):($fy = ($k * $yr + 16) / 116); $fz = ($zr > $eps)?pow($zr, 1/3):($fz = ($k * $zr + 16) / 116); $lab = array(); $lab[] = round(( 116 * $fy ) - 16); $lab[] = round(500*($fx-$fy)); $lab[] = round(200*($fy-$fz)); return $lab; } } if(!function_exists('deltaE')) { function deltaE($lab1, $lab2) { // CMC 1:1 $l = 1; $c = 1; $c1 = sqrt($lab1[1]*$lab1[1]+$lab1[2]*$lab1[2]); $c2 = sqrt($lab2[1]*$lab2[1]+$lab2[2]*$lab2[2]); $h1 = (((180000000/M_PI) * atan2($lab1[1],$lab1[2]) + 360000000) % 360000000)/1000000; $t = (164 <= $h1 AND $h1 <= 345)?(0.56 + abs(0.2 * cos($h1+168))):(0.36 + abs(0.4 * cos($h1+35))); $f = sqrt(pow($c1,4)/(pow($c1,4) + 1900)); $sl = ($lab1[0] < 16)?(0.511):((0.040975*$lab1[0])/(1 + 0.01765*$lab1[0])); $sc = (0.0638 * $c1)/(1 + 0.0131 * $c1) + 0.638; $sh = $sc * ($f * $t + 1 -$f); return sqrt( pow(($lab1[0]-$lab2[0])/($l * $sl),2) + pow(($c1-$c2)/($c * $sc),2) + pow(sqrt( ($lab1[1]-$lab2[1])*($lab1[1]-$lab2[1]) + ($lab1[2]-$lab2[2])*($lab1[2]-$lab2[2]) + ($c1-$c2)*($c1-$c2) )/$sh,2) ); } } if(!function_exists('str2rgb')) { function str2rgb($str) { $str = preg_replace('~[^0-9a-f]~','',$str); $rgb = str_split($str,2); for($i=0;$i<3;$i++) $rgb[$i] = intval($rgb[$i],16); return $rgb; } } $givenColorRGB = is_array($givenColor?$givenColor:str2rgb($givenColor); $min = 0xffff; $return = NULL; foreach($palette as $key => $color) { $color = is_array($color)?$color:str2rgb($color); if($min >= ($deltaE = deltaE(rgb2lab($color),rgb2lab($givenColorRGB)))) { $min = $deltaE; $return = $key; } } return $return; } ?>