Submit a Pull Request Report a Bug

    imagecolorclosesthwb

    (PHP 4 >= 4.0.1, PHP 5)

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

    說明

    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.

    參數

    image

    由影像建立函式(例如imagecreatetruecolor())回傳的影像資源。

    red

    紅色成分的值。

    green

    綠色成分的值。

    blue

    藍色成分的值。

    回傳值

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

    範例

    Example #1 Example of using imagecolorclosesthwb()

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

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

    imagedestroy($im);
    ?>

    上例的輸出類似於：

    HWB: 33

    更新日誌

    版本 說明
    5.3.0 This function is now available on Windows

    參見

    add a note add a note

    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;
    }
    ?>
    add a note add a note
    To Top