Upload non-text file to sharepoint REST api from php

I am using Php curl to upload file to sharepoint api. I am able to successfully upload a text file using sharepoint rest api. However, when non-text files are uploaded, the file actually is uploaded with the correct size etc but the contents look corrupted and not displaying.

In the below code, the $digest value is got correctly from sharepoint contextinfo url (not shown in this code)

Any thoughts?

$url = "http://mysharepointurl/_api/web/GetFolderByServerRelativeUrl('/<Folder Name>')/Files/Add(url='" . $name . "',overwrite=true)";

   $mimeType = "image/jpeg"; // different for pdf and text etc.
   $filename = "icon.jpg"
   $filepath = "c:\\icon.jpg";
   $cfile = getCurlValue($filepath,$mime,$filename);         
   $data = array('file' => $cfile); 

    $ch = curl_init();        
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_USERPWD, $login);
    curl_setopt($ch, CURLOPT_VERBOSE, 1);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);                
    curl_setopt($ch, CURLOPT_HTTPAUTH,  CURLAUTH_BASIC);   
    curl_setopt($ch, CURLOPT_USERAGENT,'Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7; rv:7.0.1) Gecko/20100101 Firefox/7.0.1');
    curl_setopt($ch, CURLOPT_HTTPHEADER,array("Accept: application/json;odata=verbose","Content-length:$filesize", "Content-type:$mimeType", "X-RequestDigest:$digest","binaryStringRequestBody:true","X-HTTP-Method:MERGE"));
    curl_setopt($ch,CURLOPT_POST, 1);
    curl_setopt($ch, CURLOPT_POSTFIELDS, $data); 
    $chresult = curl_exec($ch);
    curl_close($ch);    
    $resultsJSON = json_decode($chresult, true);
    $results = json_encode($resultsJSON, JSON_PRETTY_PRINT) ;     
    echo "<pre>" . $results . "</pre>";  

  function getCurlValue($filename, $contentType, $postname)
{
    // PHP 5.5 introduced a CurlFile object that deprecates the old @filename syntax
    // See: https://wiki.php.net/rfc/curl-file-upload
    if (function_exists('curl_file_create')) {
        return curl_file_create($filename, $contentType, $postname);
    }

    // Use the old style if using an older version of PHP
    $value = "@{$this->filename};filename=" . $postname;
    if ($contentType) {
        $value .= ';type=' . $contentType;
    }

    return $value;
}