PHP - getimagesize Function

Question

Does getimagesize use an extra HTTP request or can it find out the size remotely?

NOTE: The image is external

Answer 1

It can fetch it remotely or locally:

This parameter [filename] specifies the file you wish to retrieve information about. It can reference a local file or (configuration permitting) a remote file using one of the supported streams.

From the manual .

Answer 2

There will always be at least one HTTP request; otherwise how will it know what you're looking for?

If you're asking whether or not it'll download the file - yes, it will. There's no HTTP header that specifies image dimensions, so it doesn't know until the file is downloaded.