"The caching of images in the end user's browser is unrelated to the way in which the images are stored on the server. When outputting a blob (including an image), Q2A adds an HTTP header to encourage caching at the client end (see qa-blob.php)." quoting gidgreen
see http://www.question2answer.org/qa/13219/upload-images-instead-database-possible-recommended-ckeditor
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