imagecolorclosesthwb

(PHP 4 >= 4.0.1, PHP 5)

imagecolorclosesthwbGet the index of the color which has the hue, white and blackness

Descrierea

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

Get the index of the color which has the hue, white and blackness nearest the given color.

Parametri

image

O resursă - imagine, întoarsă de una din funcțiile de creare a imaginilor, cum ar fi imagecreatetruecolor().

red

Valoarea componentei roșii.

green

Valoarea componentei verzi.

blue

Valoarea componentei albastre.

Valorile întoarse

Returns an integer with the index of the color which has the hue, white and blackness nearest the given color.

Exemple

Example #1 Example of using imagecolorclosesthwb()

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

echo 
'HWB: ' imagecolorclosesthwb($im116115152);

imagedestroy($im);
?>

Exemplul de mai sus va afișa ceva similar cu:

HWB: 33

Istoricul schimbărilor

Versiune Descriere
5.3.0 This function is now available on Windows

A se vedea și

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User Contributed Notes 1 note

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0
Xong
5 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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