PHP - Propper Way To White Or

<!-- mainPage.php -->
<?php $sion_gallery_id = '450'; ?> 
<?php include(endcode.php); ?> 

<!-- endcode.php -->
<?php if (isset($sion_gallery_id)) 
 {echo "start of javascript.......album/"; echo $sion_gallery_id; echo"/end of script"; }   
  else { echo "var not on set";} ?> 

<?php
spl_autoload_register(function ($class) {
    include '/lib/' . $class . '.inc';
});

$servers = new servers;
echo $servers->get_servers(); 
echo "STATUS: ".$servers->get_status("0.0.0.0",80); //<<-- KILLS PAGE
?>

<?php
ini_set('display_errors',1);
ini_set('display_startup_errors',1);
error_reporting(E_ALL);
error_reporting(-1);

	include_once '../../Global-Includes/ServerStatus/db-connect.php';
	
//namespace xStatus;

class servers {

	private $db_Hostname	= HOSTNAME;
	private $db_Username	= USERNAME;
	private $db_Password	= PASSWORD;
	private $db_Database	= DATABASE;
	
	private $dbSQL			= '';
 
    function __construct() {
		
	} // End Construct
	
		public function get_servers(){
			
			$db = new mysqli($this->db_Hostname,$this->db_Username,$this->db_Password,$this->db_Database); 
		
				$message = '';

				// list current servers from database
				$sql = "SELECT * FROM tbl_servers";
				$res = $db->query($sql);
				
				if ($res->num_rows > 0) {
					
					$message = '<h3>Current Servers</h3>';
					
					while ($row = $res->fetch_assoc()) {
						
						$message .= $row['HostGame'] . '<br>';
						$message .= $row['HostIP'] . '<br>';
						$message .= $row['HostPort'] . '<br>';
						$message .= $this->get_status($row['HostIP'],$row['HostPort']) . '<br>'; //<<-- KILLS PAGE!
						
					}
				}
				
				$message .= "<br>End of the \"Server List\" ";
				
			return $message;
			
			}
		
	
		public function get_status(&$ServerIP,&$ServerPort){
			
			if(@stream_socket_client("tcp://".$this.$ServerIP.":".$this.$ServerPort."", $errno, $errstr, 1) !== false) {
				return "Online";
			} else {
				return "Offline";
			}
			return "Offline";
			}
	
} // End class

?>

I'm trying to convert a grayscale image to pure black and white in php using the GD library.

The purpose would be to detect the cervical cells within the image.

I'll leave the php code and a matlab one (i wrote this code in matlab and i'm trying to obtain the same result in php). Basically, im having troubles accessing each individual pixel's color and modifying it.

MATLAB:

clear all, clc, close all;


I = imread('celule.jpg');
imshow(I)
title('original');

a=rgb2gray(I);

figure;
imshow(a)
title('grayscale');

s=size(a);


for i=1:s(1)
    for j=1:s(2)

        if a(i,j)>190
            a(i,j)=0;
        else a(i,j)=255;
            end
        end
end

 figure;
 imshow(a)
 title('pure black and white');

PHP: 

<?php
 $im = imagecreatefromjpeg("celule.jpg");

function imagetograyscale($im)
{
    if (imageistruecolor($im)) {
        imagetruecolortopalette($im, false, 256);
    }

    for ($c = 0; $c < imagecolorstotal($im); $c++) {
        $col = imagecolorsforindex($im, $c);
        $gray = round(0.299 * $col['red'] + 0.587 * $col['green'] + 0.114 * $col['blue']);
        imagecolorset($im, $c, $gray, $gray, $gray);
    }
}

imagetograyscale($im);

//imagefilter($im, IMG_FILTER_CONTRAST, -255);  //i'm not looking for this effect 

header('Content-type: image/jpeg');
imagejpeg($im);

$C = imagesx($im); //width
 $L = imagesy($im); //height

 echo "Dimensiuni imagine: latime $C, inaltime $L <br>";

 //scanning through the image
 for($x = 0; $x < $L; $x++) {  //each line
    for($y = 0; $y < $C; $y++) {  //each collumn
        // pixel color at (x, y)
        $color = imagecolorat($im, $y, $x);
        $color = imagecolorsforindex($im, $color); //getting rgb values
        $RED[$x][$y] = $color["red"];  //each rgb component
        $GREEN[$x][$y] = $color["green"];
        $BLUE[$x][$y] = $color["blue"];

    }
 } 

?>

image "celule.jpg": https://i.ibb.co/6Ffj6sc/celule.jpg