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imagecolorclosesthwb

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

imagecolorclosesthwbLit l'index de la couleur spécifiée avec sa teinte, blanc et noir

Description

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

Lit l'index de la couleur spécifiée avec sa teinte, blanc et noir.

Liste de paramètres

image

Un objet GdImage, retournée par une des fonctions de création d'images, comme imagecreatetruecolor().

red

Valeur du composant rouge.

green

Valeur du composant vert.

blue

Valeur du composant bleu.

Valeurs de retour

Retourne un entier représentant d'index de la couleur.

Historique

Version Description
8.0.0 image attend une instance de GdImage désormais; auparavant, une resource gd était attendue.

Exemples

Exemple #1 Exemple avec imagecolorclosesthwb()

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

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

imagedestroy($im);
?>

Résultat de l'exemple ci-dessus est similaire à :

HWB: 33

Voir aussi

add a note

User Contributed Notes 1 note

up
7
Xong
14 years ago
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
/*
* 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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