Hey,
You can acheive it easily using CAML query as u said by firing "retrieve fields based on modified or set RowLimit"you can get the latest uploaded images.
Refer this thread
"http://stackoverflow.com/questions/824202/sharepoint-how-to-get-top-5-records-by-using-caml-query-from-a-list"
Let me know if you have any queries :)
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