Probably not easily. PHP generally runs as an apache module, so whichever user runs apache is the user recorder as the file's owner.
You could [man]chown[/man] the file to the name of the ftp user, but only if the "apache" user has right to do this, and almost 100% of the time it won't.
That kinda leaves you having to think outside the box. Can Apache run su'exec'd? Can you schedule a cron job that runs as you, or a privileged user of some kind, and create a script or cron command to do the work?
One workaround I've used in a similar situation is to have scripts upload to a subdir of /tmp and call a cron job to move them to a subfolder of the site and chown/chmod them as desired.
But, you may not have the rights to do this? Dunno if all hosts give you cron or not, or what kind of time constraints you have to be under (at the very least, you would have to say "wait 60 seconds for your image to appear on the site", and that's if your cron job is allowed to run every minute of the day....)
