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    imagecolorclosesthwb

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

    imagecolorclosesthwb — Get the index of the color which has the hue, white and blackness

    Descrizione

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

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

    Elenco dei parametri

    image

    Una risorsa immagine, restituita da una delle funzioni di creazione immagine, come imagecreatetruecolor().

    red

    Valore della componente rossa.

    green

    Valore della componente verde.

    blue

    Valore della componente blu.

    Valori restituiti

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

    Log delle modifiche

    Versione Descrizione
    8.0.0 image expects a GdImage instance now; previously, a valid gd resource was expected.

    Esempi

    Example #1 Example of using imagecolorclosesthwb()

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

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

    imagedestroy($im);
    ?>

    Il precedente esempio visualizzerà qualcosa simile a:

    HWB: 33

    Vedere anche:

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    User Contributed Notes 1 note

    up
    5
    Xong
    15 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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