Leeds X-ray Imaging Research

Digital Image Quality, Evaluation and Enhancement

# Spatial Resolution

## Modulation Transfer Function

We can understand the concept of the MTF by considering an ideal, linear, imaging system which has an input that has an x-ray intensity profile of the form of a single sinusoidal function.

The number of cycles of the signal in a millimeter is referred to as the "spatial frequency", (Units: Cycles per millimeter).

For any practical system the amplitude, or height, of the signal will be reduced or modulated. Dividing the amplitude of the output signal by the input signal, provides a measure of the "modulation transfer" of the system for that particular spatial frequency.

By repeating this process for different spatial frequencies it is possible to construct a graph of the MTF.