如何清除验证码图片背景色？

我已发布了清除验证码中的背景图像或颜色的命令，因为我的公司客户需要为用户看到验证码中的背景图像。任何人都可以帮助我如何使验证码图像背景仅显示白色。下面是我的编码：

phptextClass.php（在此文件中，背景颜色将设置随机选择，以及如何删除随机功能以将固定颜色更改为白色背景）

   <?php

  class phptextClass
  { 
        public function 
      phptext($text,$textColor,$backgroundColor='',$fontSize,$imgWidth,$imgHeight,$dir,$fileName)
    {
    /* settings */
    $font = './calibri.ttf';/*define font*/
    $textColor=$this->hexToRGB($textColor); 

    $im = imagecreatetruecolor($imgWidth,$imgHeight);  
    $textColor = imagecolorallocate($im,$textColor['r'],$textColor['g'],$textColor['b']);  

    if($backgroundColor==''){/*select random color*/
        $colorCode=array('#56aad8','#61c4a8','#d3ab92');
        $backgroundColor = $this->hexToRGB($colorCode[rand(0,count($colorCode)-1)]);
        $backgroundColor = imagecolorallocate($im,$backgroundColor['r'],$backgroundColor['g'],$backgroundColor['b']);
    }else{/*select background color as provided*/
        $backgroundColor = $this->hexToRGB($backgroundColor);
        $backgroundColor = imagecolorallocate($im,$backgroundColor['b']);
    }

    imagefill($im,$backgroundColor);    
    list($x,$y) = $this->ImageTTFCenter($im,$text,$font,$fontSize); 
    imagettftext($im,$x,$y,$text);
    if(imagejpeg($im,$dir.$fileName,90)){/*save image as JPG*/
        return json_encode(array('status'=>TRUE,'image'=>$dir.$fileName));
    imagedestroy($im);  
    }
}   
 public function phpcaptcha($textColor,$backgroundColor,$noiceLines=0,$noiceDots=0,$noiceColor='#162453')
{   
    /* Settings */
    $text=$this->random();
    $font = './font/monofont.ttf';/* font */
    $textColor=$this->hexToRGB($textColor); 
    $fontSize = $imgHeight * 0.75;

    $im = imagecreatetruecolor($imgWidth,$textColor['b']);          

    $backgroundColor = $this->hexToRGB($backgroundColor);
    $backgroundColor = imagecolorallocate($im,$backgroundColor['b']);

    /* generating lines randomly in background of image */
    if($noiceLines>0){
    $noiceColor=$this->hexToRGB($noiceColor);   
    $noiceColor = imagecolorallocate($im,$noiceColor['r'],$noiceColor['g'],$noiceColor['b']);
    for( $i=0; $i<$noiceLines; $i++ ) {             
        imageline($im,mt_rand(0,$imgWidth),$imgHeight),$noiceColor);
    }}              

    if($noiceDots>0){/* generating the dots randomly in background */
    for( $i=0; $i<$noiceDots; $i++ ) {
        imagefilledellipse($im,3,$textColor);
    }}      

    imagefill($im,$text);      

    imagejpeg($im,NULL,90);/* Showing image */
    header('Content-Type: image/jpeg');/* defining the image type to be shown in browser widow */
    imagedestroy($im);/* Destroying image instance */
    if(isset($_SESSION)){
        $_SESSION['captcha_code'] = $text;/* set random text in session for captcha validation*/
    }
}

   /*for random string*/
  protected function random($characters=6,$letters = '23456789bcdfghjkmnpqrstvwxyz'){
    $str='';
    for ($i=0; $i<$characters; $i++) { 
        $str .= substr($letters,strlen($letters)-1),1);
    }
    return $str;
    }   

 /*function to convert hex value to rgb array*/
protected function hexToRGB($colour)
{
        if ( $colour[0] == '#' ) {
                $colour = substr( $colour,1 );
        }
        if ( strlen( $colour ) == 6 ) {
                list( $r,$g,$b ) = array( $colour[0] . $colour[1],$colour[2] . $colour[3],$colour[4] . $colour[5] );
        } elseif ( strlen( $colour ) == 3 ) {
                list( $r,$b ) = array( $colour[0] . $colour[0],$colour[1] . $colour[1],$colour[2] . $colour[2] );
        } else {
                return false;
        }
        $r = hexdec( $r );
        $g = hexdec( $g );
        $b = hexdec( $b );
        return array( 'r' => $r,'g' => $g,'b' => $b );
}       

/*function to get center position on image*/
protected function ImageTTFCenter($image,$size,$angle = 8) 
{
    $xi = imagesx($image);
    $yi = imagesy($image);
    $box = imagettfbbox($size,$angle,$text);
    $xr = abs(max($box[2],$box[4]));
    $yr = abs(max($box[5],$box[7]));
    $x = intval(($xi - $xr) / 2);
    $y = intval(($yi + $yr) / 2);
    return array($x,$y);   
}
  }
  ?>

captcha.php

    <?php
    session_start();
    include("./phptextClass.php");  

   /*create class object*/
   $phptextObj = new phptextClass();    
    /*phptext function to genrate image with text*/
     $phptextObj->phpcaptcha('#162453','#fff',120,40,10,25);    
   ?>

Style.css