imagecolorclosesthwb

(PHP 4 >= 4.0.1, PHP 5, PHP 7, PHP 8)

imagecolorclosesthwb — 获取具有最接近色调、白色和黑色的颜色的索引

描述

imagecolorclosesthwb(
    GdImage $image,
    int $red,
    int $green,
    int $blue
): int

获取具有最接近给定颜色的色调、白色和黑色的颜色的索引。

参数

image: 一个 GdImage 对象，由图像创建函数（如 imagecreatetruecolor()）返回。
red: 红色分量的值。
green: 绿色分量的值。
blue: 蓝色分量的值。

返回值

返回一个整数，表示具有最接近给定颜色的色调、白色和黑色的颜色的索引。

变更日志

版本	描述
8.0.0	`image` 现在期望一个 GdImage 实例；以前，期望一个有效的 `gd` resource。

示例

示例 #1 使用 imagecolorclosesthwb() 的示例

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

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

imagedestroy($im);
?>

上面的示例将输出类似于以下内容

HWB: 33

参见

imagecolorclosest() - 获取最接近指定颜色的颜色的索引

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Xong ¶

15 年前

我写了一个函数，它使用 CMC 的 deltaE 函数。
它返回的结果比 imagecolorclosestHWB() 或 imageColorClosest() 好得多。


测试脚本在线 http://www.fuhrpark-software.de/spielwiese/color.php?color=ffff00


<?php 
/* 
 * Returns the index of the palette-color which is most similar 
 * to $givenColor. 
 * 
 * $givenColor and the colors in $palette should be either 
 * formatted as (#)rrggbb 
 * (e. g. "ff0000", "4da4f3" or "#b5d7f3") 
 * or arrays with values for red, green and blue 
 * (e. g. $givenColor = array( 0xff, 0x00, 0x00 ) ) 
 * 
 * References: 
 * function rgb2lab 
 * - http://www.f4.fhtw-berlin.de/~barthel/ImageJ/ImageJ.htm 
 * 
 * function rgb2lab & function deltaE 
 * - http://www.brucelindbloom.com 
 */ 
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; 
} 
?>

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