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    imagecolorclosesthwb

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

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

    Opis

    imagecolorclosesthwb ( resource $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.

    Parametry

    obraz

    Zasób obrazu, zwrócony przez jedną z funkcji tworzących obrazy, taką jak imagecreatetruecolor().

    red

    Wartość składowa czerwonego.

    green

    Wartość składowa zielonego.

    blue

    Wartość składowa niebieskiego.

    Zwracane wartości

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

    Rejestr zmian

    Wersja Opis
    5.3.0 This function is now available on Windows

    Przykłady

    Przykład #1 Example of using imagecolorclosesthwb()

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

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

    imagedestroy($im);
    ?>

    Powyższy przykład wyświetli coś podobnego do:

    HWB: 33

    Zobacz też:

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    User Contributed Notes 1 note

    up
    6
    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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