build an anonymizer in PHP

Hi folks, I am currently building a protype of anonymizer (a proxy for Web contents). I have set up a simple form which takes the URL, open it with fopen and writes a temporary file. Once the temporary file is created I parse <A href>, <IMG SRC> tags etc. so that they look like this: http://www.somesite.com/index.html becomes http://www.mysite.com/surf.php3?URL=http://www.somesite.com/index.html When the file has been scanned I write its contents back to the browser using echo(). URLs are parsed properly but images do not appear. However by looking at the output text I can see I achieve the same results as other commercial anonymizers. The problem lies with the way the output (binary content) is sent back to the browser. I have also tried sending back the contents as HTML with header(), to no avail. Does someone has any clues or general information on how to proceed ? Regards,