Method for estimating modulation transfer function from sample images

TL;DR

This paper introduces a novel method for estimating the modulation transfer function (MTF) from sample images by analyzing their Fourier transforms, applicable across various imaging modalities including electron microscopy and satellite imaging.

Contribution

The paper presents a new Fourier-based approach to estimate the MTF from sample images, assuming a Gaussian PSF, which is validated across different imaging types.

Findings

MTF estimation closely matches predictions from original PSFs

Method works with images from electron microscopes and satellites

Good agreement with edge profile measurements

Abstract

The modulation transfer function (MTF) represents the frequency domain response of imaging modalities. Here, we report a method for estimating the MTF from sample images. Test images were generated from a number of images, including those taken with an electron microscope and with an observation satellite. These original images were convolved with point spread functions (PSFs) including those of circular apertures. The resultant test images were subjected to a Fourier transformation. The logarithm of the squared norm of the Fourier transform was plotted against the squared distance from the origin. Linear correlations were observed in the logarithmic plots, indicating that the PSF of the test images can be approximated with a Gaussian. The MTF was then calculated from the Gaussian-approximated PSF. The obtained MTF closely coincided with the MTF predicted from the original PSF. The MTF of an x-ray microtomographic section of a fly brain was also estimated with this method. The obtained MTF showed good agreement with the MTF determined from an edge profile of an aluminum test object. We suggest that this approach is an alternative way of estimating the MTF, independently of the image type.