I wonder if its a good idea to use add_image_size or is it just a convinence feature. I say this as I think add_image_size creates images of various sizes regardless of what the usage if the image maybe
eg. I may want a thumbnail of 500×200 in my portfolio pages only. but WordPress will create images of 500×200 for all images I upload right? If I have a bunch of add_image_size, it will clutter up my uploads with useless images I will never use? Is there a better solution? Resize before upload, maybe alittle troublesome?
For image formats that are only used for a small fraction of the images, I suggest using an on-the-fly image resizer. Preferrably one that caches the images so that you only have to resize them once. I use TimThumb for a number of projects, and it’s been good enough for me.
Yes, an alternative will be to use Timthumb, which will resize images on the fly but will require some additional processing power. It does have a cache but with a large site, I believe that it will face its cache limits too.
Personally I would just keep my uploads organized in years/months folder and let it create as many copies as I want. This way, there is no additional load on the server for serving images. Because with Timthumb its not a static element anymore. And uploads are just increasing your uploads size which is really not much of a big deal, now is it?