Live Picture was the first to use what I think are called image proxies, where you can have an arbitrarily large image and only work with the screen-image sized

Live Picture was the first to use what I think are called image proxies, where you can have an arbitrarily large image and only work with the screen-image sized image. Once you have applied all the changes and click save, it will then grind through the full size image if needed. A feature that Photoshop has since added, but it appeared in Live Picture first.