[Clipart] other newbie question: how does the thumbnailing work internally?

[Schrijver]

Hi,

I have been eying the discussions about thumbnails; I also read it on  
the roadmap:
‘Add graphical thumbnails to all clip art’

But I don’t really understand how this works now, There is no script  
that programatically produces thumbnails server-side? So the thumbnail  
has to be added to the upload, i.e. as an extra PNG file?

What is the current method of implementing them than?

Question 2:  Are the thumbnail files the same as the preview images?  
(the ones you see when you click to see the details of an image)

Because I was going to suggest for those to be much bigger, like 512px  
or something; but that would not go well together with being thumbnail

Eric