I usually use a similar setup for sprites. I guess really it depends on what you require the sprite for since you may need all sorts of different sizes.

Most people either have a table full of sprite sizes (w,h) or prefix the information to the sprite data itself. This helps since you often have to refer to the sizes of your sprites for various things (for example collisions (though in most cases i have seperate data that stipulates the collision zones for any sprites)).