My friend asked me to help him with image resizing and thumbnailing. I want to ask in general, what is the best way to do this actions? I ask here, because both of us are using PHP.

His site will do many operations in one day(and at the same time, too), so it have to be simple, not CPU loading and fast.

I don't know anything about this issue, so some thoughts will be very helpful.

I was thinking about GD, but I found ImageMagick. It seems that using exec command with ImageMagick's convert utility works well on my local(I optimized resizing command many times talking with experienced users). For the moment I didn't tried APD, so I don't know about speed of command. Moreover, I haven't tried running multiple instances at the same time.

I was wondering how sites like Flickr handle this operations. Does anybody know? Is there other way, how to do this faster?

Has anyone experienced something about this issue? Thanks for any kind of help.

I have no experience with ImageMagick, but it's common to use the imagecopyresampled() function to do this with GD. (http://us.php.net/manual/en/function...yresampled.php) Resizing an image properly can be a slow process, sometimes handled by a background daemon, though most apps I've used provide for the option to create thumbnails either following the initial upload (faster load times for the viewers), or on-demand following the first download (saves disk space for thumbnails that may not be used, reduces upload script response time).

I don't know how Flickr does it -- I suppose if I were running a large site that had to do a lot of image manipulation, I'd hand it off to a server farm built uniquely for the task.