Reducing size of user avatars? - creating thumbnails

Question

User of my site upload images which are used as avatars. I have set a upload limit size of 2 MB. At most places I only require thumbnails. But users upload images with far bigger resolutions. I store these files on my file-system.

How can i create thumbnails and store them instead of large sized files?

Answer 1

Depending on your installation / server setup, you have several possibilities.

• You could use the GD library, and something like its imagecopyresized function
• Or you could use the Imagick extension, and something like its thumbnailImage method.

I would say that I've quite never seen a server without GD installed -- for Imagick, its less likely to be installed by default :-(

Another solution might be to call the convert command-line utility (it comes with ImageMagick -- independantly of any PHP extension), using something like exec to call it.

Advantage, with that, would be that you wouldn't be limited by memory_limit, as the resizing would be performed by an external tool -- but, of course, it also means that your application will rely on an external tool, which is not always nice...

If necessary, there are plenty of tutorials about GD ; for instance, those might interest you :

• How to create thumbnails with PHP and gd : it uses a batch process to generate thumbnails for many images -- which might be useful if you have to generate thumbnails for all images that you already have
• Thumbnail generation with PHP tutorial : does some stuff not often seen, like create square thumbnails, by centering the orignal image and adding some background color.