chmod for user images folders

[PurpleEdge]

I have a file upload process for end users. It creates an image and thumbnail folder.

What is the best practise for setting permissions for these folders? I can change permissions at any stage of the upload process. Should I turn-off write access when the upload is complete?

[Ruud]

When you upload through the webserver, the webserver (WB) is the owner.

Now it depends on what you want to protect.
Protection against hackers? If they have some kind of access to your server/php environment they can reset the permissions to whatever they want.
If it is to prevent overwriting by others you could set write-access off, but I would do the overwrite testing in my script (maybe it should be overwritten at some time?).

So I would probably use the "default" 755/644 (or whatever is best for your server setup) permissions for something like this.