Hi Dmitry, Dan & Olivier, Many thanks for your replies! To summarize them, I should use 'contentPostProc-all' hook to replace <img src="typo3temp/*.(jpg|gif|png) with <img src="http://cdn/*.(jpg|gif|png) Regular expressions are slow - is this the only way? I suppose str_replace of "img src=\"typo3temp" is not safe enough? Regards, John