Pixely Photos

Hi guys, I have a question about uploading photos. I’m hosting myself but through wordpress but it won’t let me upload photos bigger than 2MB. I’m not sure if it’s just me, but I think it makes the photos look really quite pixely and not that great. To my eyes they do at least and not at all on my actual iPhoto. I was wondering if anyone else thought that too and if there’s a way to change it to allow me to upload slightly larger files. Here’s an example

http://universaljetsetters.com/gorge-wildlife-park

Thank you!