Ramp filter is named for its shape in the frequency domain. This filter is designed to reduce the star artifact resulting from backprojection. It is an example of a high-pass filter, which attenuates low spatial frequencies while letting high frequency pass attenuated. The filter is linearly proportional to the frequency and, as such to the mean frequency potential where not only the information of interest resides but also the high noise. It also serves to reduce some of the low and mid frequency noise.
A ramp is an inclined surface or roadway is connecting different levels. It is a concave bend of a handrail where a sharp change in level or direction occurs, as at a stair landing. The inclined plane is one of the classical simple machines; as the name suggests, it is a flat surface whose endpoints are at different heights. By moving an object up an inclined plane rather than directly from one height to another, the amount of force required is reduced, at the expense of increasing the distance the object must travel.