note 13794 added to function.imagejpeg.php

If you call imagecreatefromjpeg and load a jpeg with 75% quality and output it with imagejpeg u can specify the new quality for e.g. 90% and u can increase quality, but output will look like 75% quality picture with the only difference that the new pic is bigger. So u should check the source quality before u alter output quality. In most cases a quality of 75% is sufficient. For previews i use 50%. But i make a check if source quality is lower than my personal output quality, i will not chance source quality ! Hope that helps your Webserver and keeps the traffic low :-) http://www.php.net/manual/de/function.imagejpeg.php