Get img thumbnails from Vimeo?

I want to get a thumbnail image for videos from Vimeo.

When getting images from Youtube I just do like this:

http://img.youtube.com/vi/HwP5NG-3e8I/2.jpg

Any idea how to do for Vimeo?

Here is same question, without any answer.

From the Vimeo Simple API docs:

Making a Video Request

To get data about a specific video, use the following url:

http://vimeo.com/api/v2/video/video_id.output

video_id The ID of the video you want information for.

output Specify the output type. We currently offer JSON, PHP, and XML formats.

So getting this URL http://vimeo.com/api/v2/video/6271487.xml

    <videos> 
      <video> 
        [skipped]
        <thumbnail_small>http://ts.vimeo.com.s3.amazonaws.com/235/662/23566238_100.jpg</thumbnail_small> 
        <thumbnail_medium>http://ts.vimeo.com.s3.amazonaws.com/235/662/23566238_200.jpg</thumbnail_medium> 
        <thumbnail_large>http://ts.vimeo.com.s3.amazonaws.com/235/662/23566238_640.jpg</thumbnail_large> 
        [skipped]
    </videos>

Parse this for every video to get the thumbnail

Here's approximate code in PHP

<?php

$imgid = 6271487;

$hash = unserialize(file_get_contents("http://vimeo.com/api/v2/video/$imgid.php"));

echo $hash[0]['thumbnail_medium'];