From where i can get image from user dropbox and display on browser

which api should i use to get image stored in user's dropbox .

i tried using /download using php

curl -X POST https://content.dropboxapi.com/2/files/download \
    --header "Authorization: Bearer " \
    --header "Dropbox-API-Arg: {\"path\": \"/Homework/math/Prime_Numbers.txt\"}

      $result=$processDB->getData($sql);

            $api_url = 'https://content.dropboxapi.com/2/files/download'; //dropbox api url
            $filename = $_FILES["file"]['tmp_name'];
            $headers = array('Authorization: Bearer '. $result[0]['token'],
                'Content-Type: application/octet-stream',
                'Dropbox-API-Arg: '.
                json_encode(
                    array(
                        "path"=>  $value['path']
                    )
                )
            );

            $ch = curl_init($api_url);

            curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
            curl_setopt($ch, CURLOPT_POST, true);

            curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);

            $response = curl_exec($ch);
            $http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
            echo($response.'<br/>');
            echo($http_code.'<br/>');

            curl_close($ch);

this the code i using.

but response all unknow code. Am i using the correct api ? or any better way.