1. A scaling system comprising: a scaling ratio generator configured to: generate a pre-scaling ratio according to a scaling ratio; and generate a post-scaling ratio according to the scaling ratio; a pre-scaler configured to generate pre-scaler image data by scaling original image data according to the pre-scaling ratio; and a post-scaler configured to: receive the original image data; receive the pre-scaler image data; and generate post-scaler image data by selectively scaling one of the original image data and the pre-scaler image data according to the post-scaling ratio.