PHP不在Ubuntu上显示图像

I'm trying to display the image if has one from a URL, like verImagem.php?img=screenshot-imgname.png. If imgname.png exists then should see the image with in a content type.

The code is working in Windows, but not on Ubuntu - tryed look at nginx config, Cloudflare, also checked if the GD Library is installed, couldn't find the problem.

Currently I'm using PHP 7.0 on Ubuntu Server 14.04.

When I try access the image it returns The image "link" cannot be displayed because it contains errors.

This script below is the one that I'm trying to display the image.

<?php
$urlFolder = "./images/screenshots/";
$requestImage = $_GET['img'];
$imageName = str_substract("screenshot-", $requestImage);

$imgpath = $urlFolder . $imageName;
$fp = fopen($imgpath, 'rb');

$ext = getimagesize($imgpath);
if ($ext['mime'] == "image/png")
    header("Content-Type: image/png");
elseif ($ext['mime'] == "image/jpeg")
    header('Content-Type: image/jpeg');
elseif ($ext['mime'] == "image/gif")
    header('Content-Type: image/gif');

header("Content-Length: " . filesize($imgpath));

fpassthru($fp);
exit;

My nginx config for the port 80. I replaced a few things with "*".

server {
    listen 80 default_server;

    root /home/www;
    # Add index.php to the list if you are using PHP
    index index.html index.htm index.nginx-debian.html index.php;
    server_name **********;;
    location / {
        # First attempt to serve request as file, then as
        # directory, then fall back to displaying a 404.
        try_files $uri $uri/ =404;

    }
    location /.well-known/acme-challenge {
        root /home/www/;
    }
    listen 443 ssl default_server;

    ssl_certificate **********;
    ssl_certificate_key **********;;

    location ~* \.(jpg|jpeg|gif|png|bmp)$ {
        try_files $uri $uri/ /index.php$is_args$args;

        add_header        Cache-Control public;
        add_header        Cache-Control must-revalidate;
        expires           7d;
    }

    location ~* \.(ico|css|js)$ {
       expires 365d;
    }
    location ~ .php$ {
                try_files $uri =404;
            fastcgi_pass unix:/run/php/php7.0-fpm.sock;
                fastcgi_index index.php;
                fastcgi_param SCRIPT_FILENAME
                $document_root$fastcgi_script_name;
                include fastcgi_params;
                fastcgi_buffers 16 16k;
                fastcgi_buffer_size 32k;
                fastcgi_read_timeout 120;

        }
    location ~ /\.ht {
        deny all;
    }
}