Imagecopymerge_alpha converting my overlays to dest img colors?

code:

<?php
header("Content-type: image/png");

    $hue = rand(0, 360);
    $sat = rand(80,100);
    $lum = rand(50,100);

    $hue /= 360;
    $sat /= 100;
    $lum /= 100;

    $result = ColorHSLToRGB($hue, $sat, $lum);
    $col1 = sprintf('%02x', $result['r']) . sprintf('%02x', $result['g']) . sprintf('%02x', $result['b']);

    $hue2 = $hue + ((mt_rand() / mt_getrandmax()) / 10) - 0.5;
    $sat2 = $sat + ((mt_rand() / mt_getrandmax()) / 10) - 0.5;
    $lum2 = $lum + ((mt_rand() / mt_getrandmax()) / 10) - 0.5;
    $result2 = ColorHSLToRGB($hue2, $sat2, $lum2);
    $col2 = sprintf('%02x', $result2['r']) . sprintf('%02x', $result2['g']) . sprintf('%02x', $result2['b']);


function ColorHSLToRGB($h, $s, $l){

        $r = $l;
        $g = $l;
        $b = $l;
        $v = ($l <= 0.5) ? ($l * (1.0 + $s)) : ($l + $s - $l * $s);
        if ($v > 0){
              $m;
              $sv;
              $sextant;
              $fract;
              $vsf;
              $mid1;
              $mid2;

              $m = $l + $l - $v;
              $sv = ($v - $m ) / $v;
              $h *= 6.0;
              $sextant = floor($h);
              $fract = $h - $sextant;
              $vsf = $v * $sv * $fract;
              $mid1 = $m + $vsf;
              $mid2 = $v - $vsf;

              switch ($sextant)
              {
                    case 0:
                          $r = $v;
                          $g = $mid1;
                          $b = $m;
                          break;
                    case 1:
                          $r = $mid2;
                          $g = $v;
                          $b = $m;
                          break;
                    case 2:
                          $r = $m;
                          $g = $v;
                          $b = $mid1;
                          break;
                    case 3:
                          $r = $m;
                          $g = $mid2;
                          $b = $v;
                          break;
                    case 4:
                          $r = $mid1;
                          $g = $m;
                          $b = $v;
                          break;
                    case 5:
                          $r = $v;
                          $g = $m;
                          $b = $mid2;
                          break;
              }
        }
        return array('r' => $r * 255.0, 'g' => $g * 255.0, 'b' => $b * 255.0);
}

$height = 144;
$width = 144;

$start = $col1;
$end = $col2;
if ($_GET['start']) {
  $start = $_GET['start'];
}
if ($_GET['end']) {
  $end = $_GET['end'];
}

$start_r = hexdec(substr($start, 0, 2));
$start_g = hexdec(substr($start, 2, 2));
$start_b = hexdec(substr($start, 4, 2));
$end_r = hexdec(substr($end, 0, 2));
$end_g = hexdec(substr($end, 2, 2));
$end_b = hexdec(substr($end, 4, 2));
$image = @imagecreate($width, $height);

for($y=0;$y<$height;$y++) {
  for($x=0;$x<$width;$x++) {
    if ($start_r == $end_r) {
      $new_r = $start_r;
    }
    $difference = $start_r - $end_r;
    $new_r = $start_r - intval(($difference / $height) * $y); 
    if ($start_g == $end_g) {
      $new_g = $start_g;
    }
    $difference = $start_g - $end_g;
    $new_g = $start_g - intval(($difference / $height) * $y);         
    if ($start_b == $end_b) {
      $new_b = $start_b;
    }
    $difference = $start_b - $end_b;
    $new_b = $start_b - intval(($difference / $height) * $y);
    $row_color = imagecolorresolve($image, $new_r, $new_g, $new_b);
    imagesetpixel($image, $x, $y, $row_color);
  }    
}

function imagecopymerge_alpha($dst_im, $src_im, $dst_x, $dst_y, $src_x, $src_y, $src_w, $src_h, $pct){ 
        // creating a cut resource 
        $cut = imagecreatetruecolor($src_w, $src_h); 

        // copying relevant section from background to the cut resource 
        imagecopy($cut, $dst_im, 0, 0, $dst_x, $dst_y, $src_w, $src_h); 

        // copying relevant section from watermark to the cut resource 
        imagecopy($cut, $src_im, 0, 0, $src_x, $src_y, $src_w, $src_h); 

        // insert cut resource to destination image 
        imagecopymerge($dst_im, $cut, $dst_x, $dst_y, 0, 0, $src_w, $src_h, $pct); 
    } 

$yagami = imagecreatefrompng('yagami.png');

imagecopymerge_alpha($image, $yagami, 0, 0, 0, 0, 144, 144, 100);

imagepng($image);
imagedestroy($image);
imagedestroy($yagami);

?>

      

        
        
        
      

    

This can be seen on the page I am using . As you can see, the eyes are not blue, black clothes are not black (colored), etc.

The overlay colors change to match the background and that's not what I want. How can I fix this?