public function SourceTransparentColorMask(&$gdimg, $hexcolor, $min_limit = 5, $max_limit = 10)
{
$width = ImageSX($gdimg);
$height = ImageSY($gdimg);
if ($gdimg_mask = ImageCreateTrueColor($width, $height)) {
$R = hexdec(substr($hexcolor, 0, 2));
$G = hexdec(substr($hexcolor, 2, 2));
$B = hexdec(substr($hexcolor, 4, 2));
$targetPixel = array('red' => $R, 'green' => $G, 'blue' => $B);
$cutoffRange = $max_limit - $min_limit;
for ($x = 0; $x < $width; $x++) {
for ($y = 0; $y < $height; $y++) {
$currentPixel = phpthumb_functions::GetPixelColor($gdimg, $x, $y);
$colorDiff = phpthumb_functions::PixelColorDifferencePercent($currentPixel, $targetPixel);
$grayLevel = min($cutoffRange, MAX(0, -$min_limit + $colorDiff)) * (255 / MAX(1, $cutoffRange));
$newColor = ImageColorAllocate($gdimg_mask, $grayLevel, $grayLevel, $grayLevel);
ImageSetPixel($gdimg_mask, $x, $y, $newColor);
}
}
return $gdimg_mask;
}
return false;
}