public function makeTransparent($transpRed = 255, $transpGreen = 255, $transpBlue = 255)
    {
        $curX = imagesx($this->image);
        $curY = imagesy($this->image);

        $imw = imagecreatetruecolor($curX, $curY);

        $color = imagecolorallocate($imw, $transpRed, $transpGreen, $transpBlue);
        imagefill($imw, 0, 0, $color);
        imagecolortransparent($imw, $color);

        imagecopyresampled($imw, $this->image, 0, 0, 0, 0, $curX, $curY, $curX, $curY);

        $this->image = $imw;

        return $this;
    }