PHP - Show thumbnail

Hi Jane, I would appreciate that very much! :)

Until now I've created dropbox.php:

<?php

$ch = curl_init();

curl_setopt($ch, CURLOPT_URL, "https://api.dropboxapi.com/2/files/list_folder");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_CAINFO, "cacert.pem");
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 0);
curl_setopt($ch, CURLOPT_POSTFIELDS, '{"path":"/images","recursive":true,"include_media_info":true,"include_deleted":false}');
curl_setopt($ch, CURLOPT_POST, 1);

$headers = array();
$headers[] = "Authorization: Bearer XXX_SECRET_TOKEN_XXX";
$headers[] = "Content-Type: application/json";
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);

$result = curl_exec($ch);
if (curl_errno($ch)) {
    echo 'Error:' . curl_error($ch);
}
curl_close ($ch);

$json = json_decode($result, true);

I filter the $json['entries'] with some functions, which hand me all data of the 5 images I need.
Eventually, I want to display 5 thumbnails on my page, so I figured I call them separately using another file, image.php.
Image.php should then (in my opinion) serve the image as if it were an image file. That is where I get lost:

Image.php looks as follows:

<?PHP

$ch = curl_init();

curl_setopt($ch, CURLOPT_URL, "https://content.dropboxapi.com/2/files/get_thumbnail");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_CAINFO, "cacert.pem");
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 0);
curl_setopt($ch, CURLOPT_POSTFIELDS, '{"path":"/DropsyncFiles/2017.09.01_22.36.01/20170901223632654.jpg","format":{".tag":"jpeg"},"size":{".tag":"w1024h768"}');
curl_setopt($ch, CURLOPT_POST, 1);

$headers = array();
$headers[] = "Authorization: Bearer XXX_SECRET_TOKEN_XXX";
$headers[] = "Content-Type: application/json";
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);

$result = curl_exec($ch);
if (curl_errno($ch)) {
    echo 'Error:' . curl_error($ch);
}
curl_close ($ch);

header('Content-Type: image/jpeg');
imagejpeg( $result );
imagedestroy( $result );

?>

As you can see, I've lost my way and I have no cluo on what I'm doing. I've read the documentation stating that the respons is the image data but I can't seem to output it in the right way. The file however takes some time to load, so something's happening :)

Should you whish some additional info, please let me know!

Thank you,
Knal